Entitled pressure-resistant member and a manufacturing method thereof consisting of austenitic heat resistant alloy and the alloy
Technical field

[0001]
　The present invention has a high temperature strength much higher than the conventional heat-resistant alloys, even longer austenitic heat resistant alloy is excellent in toughness after use excellent in hot workability as well as heat and pressure-resistant member formed of the alloy and its It relates to a method for manufacturing. Specifically, power boiler, chemical industry pipe in the plant, such as material, a plate material of heat- and pressure-resistant members, rods, high-temperature strength to be used as a forging Hinto, especially excellent in creep rupture strength and high tissue after prolonged use Stability the method of excellent toughness, further hot workability, especially the austenitic heat resistant alloys and heat- and pressure-resistant member formed of the alloy high temperature ductility at 1150 ° C. or higher containing 28-38 wt% of Cr, which is remarkably improved manufacturing on.
Background technique

[0002]
　Conventionally, boilers used in a high temperature environment, in chemical plants, etc., SUS304H as device materials, SUS316H, SUS321H, so-called "18-8 austenitic stainless steel" such as SUS347H have been used.
[0003]
　However, in recent years, the use conditions of the device in a high-temperature environment is remarkably severer, required performance becomes stricter for the materials used with it, high-temperature strength at 18-8 austenitic stainless steel described above which have been used conventionally, among others, creep rupture strength has become a situation of insufficient significantly. So, it'll be contained in an appropriate amount of various elements, austenitic stainless steel having improved creep rupture strength have been developed.
[0004]
　Meanwhile, recently, for example in the field of thermal power generation boiler, a conventional plans to increase the steam temperature was at most 600 ° C. of about more than 700 ° C. has been promoted. Then, in this case, since the temperature of the member to be used exceeds far the 700 ° C., even using the above newly developed austenitic stainless steel, insufficient creep rupture strength and corrosion resistance is there.
[0005]
　In general, in order to improve the corrosion resistance, it is effective to increase the Cr content in the steel. However, in the case of increasing the Cr content is, for example, as seen in SUS310S containing Cr of about 25 wt%, the creep rupture strength of 600 ~ 800 ° C. is lower rather than 18-8 stainless steel it is by will, also occur toughness degradation due to σ phase precipitation. Furthermore, in the order of 25% by weight even by increasing the Cr content, we can not ensure sufficient corrosion resistance in a severe corrosive environment.
[0006]
　Therefore, in Patent Documents 1-7, increasing the content of Cr and Ni, moreover, it contains a one or more Mo and W, and heat-resistant alloy with improved creep rupture strength as high temperature strength is disclosed there.
[0007]
　Furthermore, demand for high-temperature strength properties increasingly stringent, in particular, against the demand for creep strength at break of, in Patent Document 8, by mass% Cr and 28 to 38%, containing Ni 30 ~ 50% heat-resistant alloy is also in Patent documents 9-14, in mass% Cr and 28 to 38%, heat-resistant alloy containing 35-60% of Ni is disclosed. Any of the above heat resistant alloys proposed in Patent Documents 8 to 14 leverages the alpha-Cr phase deposition of the body-centered cubic structure mainly composed of Cr, which was aimed to improve further creep rupture strength is there.
CITATION

Patent Document

[0008]
Patent Document 1: JP Laid-Open Publication No. 60-100640
Patent Document 2: JP Laid-Open Publication No. 61-174350
Patent Document 3: JP Laid-Open Publication No. 61-276948
Patent Document 4: JP Laid-Open Publication No. 62-63654
Patent Literature 5: Laid-open Publication No. Sho 64-55352
Patent Document 6: Japanese Patent Publication No. 2-200756
Patent Document 7: Japanese Patent Publication No. 3-264641
Patent Document 8: Japanese Patent Publication No. 7-34166
Patent Document 9: JP 7 Publication No. -70681
Patent Document 10: JP 7-216511
Patent Document 11: Japanese Patent Application Publication No. 7-331390
Patent Document 12: JP 8-127848 A
Patent Document 13: Japanese Patent Application Publication No. 8-218140
Patent literature 14: Unexamined Patent Publication No. 10-96038 Gazette
Summary of the Invention

Problems that the Invention is to Solve

[0009]
　Heat-resistant alloy as disclosed in Patent Documents 1-7 described above, under the harsh environment in which the steam temperature becomes even higher 700 ° C., was necessarily can not be obtained sufficiently high creep rupture strength.
[0010]
　Moreover, it has become even with the heat-resistant alloy as disclosed in Patent Documents 8 to 14, not be sufficient for high creep rupture strength that has recently been challenged situation. Further, heat-resistant alloys disclosed in Patent Documents 8 to 14, depending on its alloy composition, it was also toughness after prolonged use is not sufficient. Moreover, for these heat-resistant alloy, the hot workability, in particular, it is also desirable to further improve the hot workability at 1150 ° C. or more high temperature side. This, in the case of producing a seamless steel pipe by using the hot workability poor material is often manufactured tube in hot extrusion, hot workability at 1150 ° C. or more high temperature side is not if sufficient, the internal temperature of the material by the processing heat generation is higher than the heating temperature, two cracks, because defects occur such rash flaws. Note that if an insufficient hot workability at 1150 ° C. or more high temperature side, Mannesmann - also in the case of the piercer by perforation step such as a mandrel mill method, the above-mentioned defects occur.
[0011]
　In view of the above situation, the present invention is, conventional heat-resistant alloys, among others, even greater high-temperature strength as compared to the disclosed heat resistant alloys in the Patent Documents 8 to 14, among others, which has a creep rupture strength, high temperature in and toughness satisfactory for excellent structural stability even when used for a long time, further hot workability, in particular, austenite containing Cr high temperature ductility is remarkably improved at 1150 ° C. or higher 28-38 wt% and to provide a system heat-resistant alloy.
Means for Solving the Problems

[0012]
　The present inventors, as a base component, in mass% Cr and 28 to 38%, more than 40% of Ni was contained in 60% or less, various heat resistant alloys precipitation strengthening of alpha-Cr phase can be utilized used, were investigated creep rupture strength, structural stability in long-term use, the hot workability and the like. As a result, we found the following findings (a) ~ (g).
[0013]
　It is contained the W of (a) the proper amount, Fe 2 W type Laves phase and Fe of 7 W 6 type μ phase precipitates, creep rupture strength is significantly improved.
[0014]
　(B) 28 when they contain to 38% Cr, as long as it can form a solid solution of W in alpha-Cr phase precipitated, long alpha-Cr phase growth coarsening during the use at high temperatures is suppressed because, a sharp decrease of creep rupture strength in the long-term side does not occur.
[0015]
　(C) Conventionally, in general, Mo and W have been considered to have the same action and effect, the alloy containing W and 28 to 38% of Cr, Mo is contained in combination in this case, sometimes σ phase long side is precipitated, thus, it may cause creep rupture strength, a reduction in ductility and toughness.
[0016]
　Relative to (d) Cr content, by appropriately controlling the content of Ni is an austenite stabilizing element, it is possible to suppress stably and reliably σ phase precipitation during extended use at high temperatures, Moreover, it is possible to deposit the optimal amount of alpha-Cr phase. In the case where the alloy contains in combination the Co, to the Cr content, the sum of both the amount of Ni and Co (that is, "Ni + Co") by appropriately controlled, stable and reliable it is possible to suppress the σ phase precipitation during extended use at high temperatures, moreover, it is possible to deposit the optimal amount of alpha-Cr phase.
[0017]
　(E) Zr is commonly known as "grain boundary strengthening element", but in the case of heat-resistant alloys precipitation strengthening of alpha-Cr phase can be utilized has the effect of improving the creep rupture strength. Further, by appropriately controlling the content of Al in accordance with the content of Zr, the creep rupture strength is significantly improved.
[0018]
　(F) Ti also precipitation strengthening of alpha-Cr phase improves the creep rupture strength of the heat resistant alloy capable of utilizing. Therefore, the Ti By containing complex with the Zr, it is possible to further enhance the creep rupture strength even to promote the precipitation of alpha-Cr phase.
[0019]
　(G) The above Ti and Zr, so lower the melting point of the heat-resistant alloy, the hot workability, in particular, reduces the hot workability at 1150 ° C. or more high temperature side, further, resistance to hot cracking during welding there is also reduced. However, depending on the content of Ti and Zr, by controlling the appropriate content of P, in terms of maintaining high creep rupture strength, hot workability in a stable and reliable 1150 ° C. or more high temperature side can improve further, it is also possible to enhance the resistance to hot cracking during welding.
[0020]
　The present invention has been completed based on the above findings and has as its gist, austenitic heat resistant alloy shown in the following (1) to (3), the pressure-resistant member and shown in (4) (5) in the manufacturing method of the heat- and pressure-resistant members shown.
[0021]
　(1) in mass%, C: 0.02% 0.15% beyond hereinafter Si: 2% or less, Mn: 3% or less, P: 0.03% or less, S: 0.01% or less, cr: 28 ~ 38%, Ni : 60% over 40% or less, W: 15% more than 3% or less, Ti: 0.05 ~ 1.0%, Zr: 0.005 ~ 0.2% , Al: contains 0.01 to 0.3% and, N: 0.02% or less, Mo: less than 0.5%, the balance being Fe and impurities, further the following (1) ~ (3) austenitic heat resistant alloy which satisfies the equation.
　≦ 3 P / {200 (Ti + 8.5 × Zr)} · · ·
　(1) 1.35 × Cr ≦ Ni ≦ 1.85 × Cr · · ·
　(2) Al ≧ 1.5 × Zr · · · ( 3)
　in addition, element symbol in the formulas represents the content by mass percent of the element.
[0022]
　(2) in mass%, C: 0.02% 0.15% beyond hereinafter Si: 2% or less, Mn: 3% or less, P: 0.03% or less, S: 0.01% or less, cr: 28 ~ 38%, Ni : 60% over 40% or less, Co: 20% or less, W: 15% more than 3% or less, Ti: 0.05 ~ 1.0%, Zr: 0. 005 ~ 0.2%, Al: contains 0.01 to 0.3% and, N: 0.02% or less, Mo: less than 0.5%, the balance being Fe and impurities, further , (1) below, (3) and (4) austenitic heat resistant alloy which satisfies the equation.
　≦ 3 P / {200 (Ti + 8.5 × Zr)} · · ·
　(1) 1.35 × Cr ≦ Ni + Co ≦ 1.85 × Cr · · ·
　(4) Al ≧ 1.5 × Zr · · · ( 3)
　in addition, element symbol in the formulas represents the content by mass percent of the element.
[0023]
　(3) mass%, further, the characterized by containing one or more elements belonging to one or more groups selected from the group of <1> to <3> described below (1) or (2 austenitic heat resistant alloy according to).
<1> Nb: 1.0% or less, V: 1.5% or less, Hf: 1% or less and B: 0.05% or
　less, <2> Mg: 0.05% or less, Ca: 0.05% hereinafter, Y: 0.5% or less, La: 0.5% or less, Ce: 0.5% or less, Nd: 0.5% or less and Sc: 0.5% or
　less, <3> Ta: 8% or less , Re: 8% or less, Ir: 5% or less, Pd: 5% or less, Pt: 5% or less and Ag: 5% or less.
[0024]
　(4) above (1) to (3) to creep resistance and structural stability in high heat and pressure-resistant members in a high temperature range, characterized in that it consists of austenitic heat resistant alloy according to any one of.
[0025]
　(5) The austenitic heat resistant alloy according to any one of (1) to (3), the following steps (i), characterized in that it successively treated with (ii) and (iii) above (4 method for producing a heat- and pressure-resistant member with excellent structural stability and creep resistance in a high temperature range according to).
　Step (i): before final processing by hot or cold, at least once, heating to 1050 ~ 1250 ° C..
　Step (ii): a final plastic working of reduction of area of 10% or more by hot or cold.
　Step (iii): a final heat treatment of cooling after heating maintained at a temperature in the range of 1100 ~ 1250 ° C..
[0026]
　The "impurities" in "Fe and impurities" as the balance, when producing the alloy industrially, refers to those mixed like from ore and scrap or the environment as a raw material. In addition, the "high temperature range" is a temperature range where the creep deformation, 600 ° C. or higher in the present invention alloy, the upper limit of the strength refers to the temperature range of about 600 ~ 900 ° C. In view.
Effect of the Invention

[0027]
　Austenitic heat resistant alloy of the present invention has excellent high-temperature strength than the conventional heat-resistant alloys, among others, which has a creep rupture strength, and toughness was good because a long time is excellent in structural stability and used at high temperatures further hot workability, in particular, excellent high temperature ductility at 1150 ° C. or higher. Therefore, power boiler, chemical industry pipe in the plant, such as material, a plate material of heat- and pressure-resistant member, bar, can be suitably used as a forging Hinto.
DESCRIPTION OF THE INVENTION

[0028]
　It will be described in detail below each requirement of the present invention. It is to be noted. "%" For the content of each element in the following description means "mass%".
[0029]
　(A) austenitic heat resistant alloy
　C: 0.15% exceeds 0.02% or less
　C is ensured tensile strength and creep rupture strength required when used in a high temperature environment to form a carbide It has the effect of. In order to exert this effect, it is necessary to include C weight greater than 0.02%. However, only the amount of undissolved carbides after the solution heat treatment when the content exceeds 0.15% of C is increased, does not contribute to improvement of high temperature strength, furthermore, other mechanical properties such as toughness and weldability deteriorate. Therefore, C content is 0.15% or less than 0.02%. The preferred range of C content is not more than 0.13% greater than 0.03%, more preferred range is 0.12% or less exceed 0.05%.
[0030]
　Si: 2% or less
　Si is added as a deoxidizing element. Further, Si is oxidation resistance, an element effective to enhance steam oxidation resistance and the like. However, an increasing number of content Si, in particular, when it exceeds 2%, sigma since promote the formation of intermetallic compounds of equality, resulting in decrease in toughness and ductility stability tissue at high temperatures is deteriorated. Moreover, weldability, hot workability also drops. Therefore, the content of Si is 2% or less. When the toughness and ductility are important, the content of Si is preferably 1% or less. If deoxidation by another element is sufficiently secured, it is not necessary to particularly specify any lower limit for the content of Si.
[0031]
　Incidentally, the action deoxidation, oxidation resistance, when importance is attached to steam oxidation resistance, etc., the content of Si is preferably to 0.05% or more, more preferably be 0.1% or more.
[0032]
　Mn: 3% or less
　Mn, as well as has a deoxidizing effect similar to the Si, it has the effect of the S which is inevitably contained in the alloy fixed to as a sulfide to improve hot workability. However, if the content of Mn exceeds 3%, the promoting the precipitation of intermetallic compounds of σ phase etc., mechanical properties such as structural stability and high-temperature strength is deteriorated. Therefore, the Mn content was 3% or less.
[0033]
　Incidentally, it is not necessary to provide a lower limit for the content of Mn, Mn content in the case of emphasizing the hot workability improving effect, preferably 0.1% or more. The content of Mn is more preferably 0.2 to 2% Tosureba more preferably 0.2 to 1.5%.
[0034]
　P: 0.03% or less
　P is inevitably mixed into the alloy as an impurity, it lowers the hot workability. In particular, when the content of P exceeds 0.03%, the hot workability becomes remarkable. Accordingly, the content of P is set to 0.03% or less.
[0035]
　The content of P in terms of restricted below 0.03% above,
P ≦ 3 / {200 (Ti + 8.5 × Zr)} · · · (1)
must also be met expression.
[0036]
　S: 0.01% or less
　S is unavoidably mixed into the alloy as an impurity in the same manner as P, it lowers the hot workability. In particular, when the content of S exceeds 0.01%, a decrease in hot workability becomes remarkable. Therefore, the content of S is 0.01% or less.
[0037]
　When it is desired to ensure good hot workability, the content of S is preferably 0.005% or less, more preferably it is 0.003% or less.
[0038]
　Cr: 28 ~
　38% Cr has oxidation resistance, steam oxidation resistance, corrosion resistance improving effect, such as high-temperature corrosion resistance. Further, Cr, in the present invention, precipitates as alpha-Cr phase is an essential element for increasing the creep rupture strength. However, the content thereof is less than 28%, not these effects can not be obtained. On the other hand, increasing number content of Cr, in particular, when it exceeds 38%, the hot workability is deteriorated and further destabilize the tissue due to σ phase precipitates. Accordingly, the content of Cr is set to 28 to 38%. It is preferable to contain Cr in an amount exceeding 30%.
[0039]
　Ni: 60% or less beyond the 40%
　Ni is an essential element for ensuring a stable austenitic structure. In the present invention containing 28-38% of Cr, in order to stably precipitate the alpha-Cr phase suppresses the precipitation of σ phase, it is necessary Ni content of more than 40%. However, it becomes excessive content of Ni, in particular, when it exceeds 60%, depending on the content of Cr not alpha-Cr phase is sufficiently precipitated, further impaired even economy. Therefore, the content of Ni was 60% or less than 40%.
[0040]
　The content of Ni is in terms of restricted below 60% more than 40% of
said, 1.35 × Cr ≦ Ni ≦ 1.85 × Cr · · · (2)
meet or even expression, later when including in combination the Co amounts
to, 1.35 × Cr ≦ Ni + Co ≦ 1.85 × Cr · · · (4)
should satisfy also expression.
[0041]
　W: 15% or less exceed 3%
　W not only contributes to an improvement in creep rupture strength as a solid solution strengthening element in solid solution in the matrix, Fe 2 W type Laves phase and Fe of 7 W 6 type It precipitates as μ phase, a very important element to significantly improve the creep rupture strength. Furthermore, W is 28 to 38% of a solid solution in the alpha-Cr phase precipitated in the present invention containing Cr, suppressing long alpha-Cr phase during use growth coarsening at high temperature, It has the effect of suppressing a rapid reduction in creep rupture strength at long side. However, the content of W is 3% or less, the effects can not be obtained. On the other hand, also contain W in an amount exceeding 15%, only costly effects of the is saturated, moreover, microstructural stability and hot workability is deteriorated. Therefore, the content of W was 15% or less than 3%. The content of W is preferably greater than 3% to 13% or less. Incidentally, W content in the case of further emphasizes the effect of improving the creep rupture strength, and more preferably to 13% more than 6% or less.
[0042]
　Ti: 0.05 ~
　1.0% Ti is an important element to increase the creep rupture strength by promoting the precipitation of alpha-Cr phase. In particular, by containing complex with Zr of described below the amount of Ti, alpha-Cr phase deposition is further promoted, it is possible to increase the creep rupture strength. However, the content of Ti is sufficient effect can not be obtained is less than 0.05%, whereas, the hot workability is deteriorated when it exceeds 1.0%. Therefore, the Ti content was 0.05 to 1.0%. The content of Ti is more preferably in the 0.1 to 0.9%, Tosureba more preferably 0.2 to 0.9 percent. A more preferred upper limit of the Ti content is 0.5%.
[0043]
　The content of Ti is, after limits 0.05 to 1.0% above,
P ≦ 3 / {200 (Ti + 8.5 × Zr)} · · · (1)
must also meet the formula is there.
[0044]
　Zr: 0.005 ~
　0.2% Zr, like Ti, is an important element to increase the creep rupture strength by promoting the precipitation of alpha-Cr phase. In particular, by containing complex with Ti in the amounts described above of Zr, alpha-Cr phase deposition is further promoted, it is possible to increase the creep rupture strength. However, the content of Zr is not sufficient effect can be obtained with less than 0.005%, while the hot workability is deteriorated when it exceeds 0.2%. Therefore, the content of Zr was 0.005 to 0.2%. The content of Zr is more preferably 0.01 to 0.1 percent, Tosureba more preferably 0.01 to 0.05 percent.
[0045]
　The content of Zr is in terms of restricted 0.005 to 0.2% above,
P ≦ 3 / {200 (Ti + 8.5 × Zr)} · · ·
(1) Al ≧ 1.5 × Zr · · · (3)
2 two equations must also be met.
[0046]
　Al: 0.01 ~
　0.3% Al is an element having a deoxidizing effect, the exerts its effects is necessary amount containing at least 0.01%. Incidentally, when containing a large amount of Al is gamma 'phase can increase the creep rupture strength by precipitating, in the present invention, the proper amount of W, is contained Ti and Zr, alpha-Cr phase and Laves phase etc. since the creep rupture strength in the composite precipitation strengthening can be dramatically increased by, strengthening by gamma 'phase is not necessary. Moreover, when the content of Al exceeds 0.3%, there may hot workability, ductility and toughness are deteriorated. Accordingly, the hot workability, ductility, with an emphasis on toughness, the content of Al is 0.01 to 0.3%.
[0047]
　The content of Al, in terms of restricted from 0.01 to 0.3%
above, Al ≧ 1.5 × Zr · · · (3)
must also be met expression.
[0048]
　N: 0.02% or less
　in the present invention contain as an essential element of Zr and Ti for precipitation accelerating the alpha-Cr phase, the ordinary melting method, which is an element contained inevitably N is, ZrN and to avoid the consumption of Zr and Ti caused by the formation of TiN, its content should be reduced as much as possible. However, extreme reduction of the N content impairs required to economy special melting method and high purity raw materials. Therefore, the content of N is set to not more than 0.02%. A preferable content of N is 0.015% or less.
[0049]
　Mo: less than 0.5%
　conventional, Mo is a solid solution in the matrix, as an element contributing to the improvement of creep rupture strength as a solid solution strengthening element, has been considered an element having a function similar to that of a W. However, a study of the present inventors, when Mo is contained in the composite in an alloy containing W and Cr in the amounts described above, may σ phase long side is precipitated, Therefore, creep rupture strength, it may cause a reduction in ductility and toughness were found. Therefore, Mo content is desirably as low as possible, and less than 0.5%. The content of Mo is more preferably limited to less than 0.2%.
[0050]
　One austenitic heat resistant alloy of the present invention, in addition to the above elements, with the balance being Fe and impurities. One Another austenitic heat resistant alloy of the present invention, in addition to the above elements, further, those containing Co in the following amounts.
[0051]
　Co: 20% or less
　Co, as well as has the effect of stabilizing the same austenitic organization and Ni, since it is an element contributing to the improvement of creep rupture strength, it may contain Co in order to obtain the effect of the . However, also contain Co in excess of 20% are only costly to the above effects are saturated, moreover, the hot workability also drops. Therefore, the amount of Co in the case of containing a 20% or less. The upper limit of the Co content is preferably set to 15%. Meanwhile, in order to ensure the improvement of the effect and the creep rupture strength to stabilize the austenite structure of the above-described Co is preferably to 0.05% the lower limit of the Co content, by a 0.5% if more preferred.
[0052]
　Incidentally, in the case containing Co, the content is, after limited to less than 20% of
the, 1.35 × Cr ≦ Ni + Co ≦ 1.85 × Cr · · · (4)
must also meet the formula is there.
[0053]
　One still another austenitic heat resistant alloy of the present invention, in addition to the elements from the above C to Mo, or in addition to the elements of the above C to Co, furthermore, <1> to below < 3> is austenitic heat resistant alloys containing one or more elements belonging to one or more groups selected from the group of.
　<1> Nb: 1.0% or less, V: 1.5% or less, Hf: 1% or less and B: 0.05% or
　less, <2> Mg: 0.05% or less, Ca: 0.05% hereinafter, Y: 0.5% or less, La: 0.5% or less, Ce: 0.5% or less, Nd: 0.5% or less and Sc: 0.5% or
　less, <3> Ta: 8% or less , Re: 8% or less, Ir: 5% or less, Pd: 5% or less, Pt: 5% or less and Ag: 5% or less.
[0054]
　The following describes the above-mentioned elements.
[0055]
　<1> is an element of the group of Nb, V, Hf and B, all have an effect of improving the high temperature strength and creep rupture strength. Therefore, adding positively when it is desired to obtain greater high-temperature strength and creep rupture strength, one or more of these elements may be contained within the following range.
[0056]
　Nb: 1.0% or less
　Nb has the effect of forming carbonitrides to fine crystal grains improves the high temperature strength and creep rupture strength to improve the ductility. Thus it may contain Nb in order to obtain these effects. However, if the content of Nb exceeds 1.0%, hot workability and toughness decreases. Therefore, the amount of Nb in the case of containing a 1.0% or less. The upper limit of the Nb content is preferably set to 0.9%. On the other hand, high-temperature strength of the above-mentioned Nb, in order to ensure the effect of improving the creep rupture strength and ductility, it is preferable to 0.05% or lower limit of the Nb content, Tosureba more preferably 0.1% .
[0057]
　V: 1.5% or less
　V has the effect of improving the high temperature strength and creep rupture strength by forming carbo-nitrides. Thus it may contain V in order to obtain these effects. However, if the content of V exceeds 1.5%, it reduces the high temperature corrosion resistance, leading to further deterioration of ductility and toughness due to precipitation of a brittle phase. Therefore, the amount of V in the case of containing more than 1.5%. The upper limit of the V content is preferably set to 1%. Meanwhile, in order to ensure the effect of improving high-temperature strength and creep rupture strength of the above-described V is preferably to 0.02% the lower limit of V content, Tosureba more preferably 0.04%.
[0058]
　Hf: 1% or less
　and Hf, because it has a function of improving the contribution to the high temperature strength and creep rupture strength to precipitation strengthening as a carbonitride may contain Hf, in order to obtain these effects. However, if the content of Hf exceeds 1%, workability and weldability are impaired. Therefore, the amount of Hf in the case of incorporating more than 1%. The upper limit of the Hf content is preferably set to 0.8%, 0.5% Tosureba more desirable. Meanwhile, in order to ensure the high temperature strength and creep rupture strength improving effect of the above-mentioned Hf is preferably that the lower limit of the Hf content 0.01% Tosureba more preferably 0.02%.
[0059]
　B: 0.05% or less
　B is a grain boundary in B alone, or present in the carbonitride, the grain boundary sliding suppression and finely dispersed precipitation accelerating carbonitrides by grain boundary strengthening during the use at high temperatures has the effect of improving the high temperature strength and creep rupture strength. However, if the content of B exceeds 0.05%, weldability is deteriorated. Therefore, the amount of B in the case of containing more than 0.05%. The upper limit of the B content is preferably set to 0.01%, 0.005% Tosureba more desirable. Meanwhile, in order to ensure the effect of improving high-temperature strength and creep rupture strength of the above-described B is preferably that the lower limit of the content of 0.0005% Tosureba more preferably 0.001%.
[0060]
　The upper limit of the total content of the elements from the above Nb to B may be 3.55%. It is more preferable upper limit of the total content of the above is 2.5%.
[0061]
　Mg is an element of the group of <2>, Ca, Y, La, Ce, Nd and Sc has the effect of both improving the fixed hot workability S as sulfides. Therefore, adding the positively when it is desired to obtain a better hot workability, one or more of these elements may be contained within the following range.
[0062]
　Mg: 0.05% or less
　Mg, so has the effect of improving the hot workability by fixing S, which is inevitably contained as sulfides in the alloy, and contains Mg in order to obtain this effect it may be. However, if the content of Mg exceeds 0.05%, the cleanliness of drops, rather hot workability and ductility is deteriorated. Therefore, the amount of Mg in the case of containing more than 0.05%. The upper limit of the Mg content is preferably set to 0.02%, Tosureba more desirably 0.01%. Meanwhile, in order to ensure the hot workability improving effect of the above-described Mg is preferably to 0.0005% the lower limit of the Mg content, Tosureba more preferably 0.001%.
[0063]
　Ca: 0.05% or less
　Ca, since the S of inhibiting hot workability fixed to the sulfide has the effect of improving the hot workability may contain Ca in order to obtain this effect . However, if the content of Ca exceeds 0.05%, the cleanliness of drops, rather hot workability and ductility is deteriorated. Therefore, the amount of Ca in the case of containing more than 0.05%. The upper limit of the Ca content is preferably set to 0.02%, Tosureba more desirably 0.01%. Meanwhile, in order to ensure the hot workability improving effect of the above-described Ca is preferably to 0.0005% the lower limit of the Ca content, Tosureba more preferably 0.001%.
[0064]
　Y: 0.5% or less
　Y have the effect of improving the hot workability by fixing S as sulfides. Also, the Y, Cr of the steel surface 2 O 3 to improve the adhesion of the protective coating, in particular, effect of improving the oxidation resistance at the time of repeated oxidation, and further, contributes to grain boundary strengthening, the creep rupture strength and also it has a function of improving the creep rupture ductility. However, if the content of Y exceeds 0.5%, inclusions are more becomes workability and weldability are impaired, such as oxides. Therefore, the amount of Y in the case of containing a 0.5% or less. The upper limit of the Y content is preferably set to 0.3%, 0.15% Tosureba more desirable. Meanwhile, in order to ensure the above-described effect of Y, it is preferable to set the lower limit of the content of 0.0005%. In a more preferred lower limit is 0.001% of the Y content, yet more preferably 0.002%.
[0065]
　La: 0.5% or less
　La has an effect of improving the hot workability by fixing S as sulfides. Moreover, the La, Cr of the steel surface 2 O 3 to improve the adhesion of the protective coating, in particular, effect of improving the oxidation resistance at the time of repeated oxidation, and further, contributes to grain boundary strengthening, the creep rupture strength and also it has a function of improving the creep rupture ductility. However, if the content of La exceeds 0.5%, inclusions are more becomes workability and weldability are impaired, such as oxides. Therefore, the amount of La in the case of containing a 0.5% or less. The upper limit of the La content is preferably set to 0.3%, 0.15% Tosureba more desirable. Meanwhile, in order to ensure the above-described effect of La is preferably set to 0.0005% the lower limit of the La content. In a more preferred lower limit is 0.001% of the La content, yet more preferably 0.002%.
[0066]
　Ce: 0.5% or less
　Ce also have the effect of improving the hot workability by fixing S as sulfides. Also, the Ce, Cr of the steel surface 2 O 3 to improve the adhesion of the protective coating, in particular, effect of improving the oxidation resistance at the time of repeated oxidation, and further, contributes to grain boundary strengthening, the creep rupture strength and also it has a function of improving the creep rupture ductility. However, if the content of Ce exceeds 0.5%, inclusions are more becomes workability and weldability are impaired, such as oxides. Therefore, the amount of Ce in the case of containing a 0.5% or less. The upper limit of the Ce content is preferably set to 0.3%, 0.15% Tosureba more desirable. Meanwhile, in order to ensure the above-described effect of Ce, it is preferable to set the lower limit of the content of 0.0005%. In a more preferred lower limit is 0.001% of Ce content, yet more preferably 0.002%.
[0067]
　Nd: 0.5% or less
　Nd has the effect of improving the hot workability by fixing S as sulfides. In addition, the Nd, Cr of the steel surface 2 O 3 to improve the adhesion of the protective coating, in particular, effect of improving the oxidation resistance at the time of repeated oxidation, and further, contributes to grain boundary strengthening, the creep rupture strength and also it has a function of improving the creep rupture ductility. However, if the content of Nd exceeds 0.5%, inclusions are more becomes workability and weldability are impaired, such as oxides. Therefore, the amount of Nd in the case of containing a 0.5% or less. The upper limit of the Nd content is preferably set to 0.3%, 0.15% Tosureba more desirable. Meanwhile, in order to ensure the above-described effect of Nd, it is preferable to set the lower limit of the content of 0.0005%. In a more preferred lower limit is 0.001% of Nd content, yet more preferably 0.002%.
[0068]
　Sc: 0.5% or less
　Sc also has the effect of improving the hot workability by fixing S as sulfides. Further, the Sc, Cr of the steel surface 2 O 3 to improve the adhesion of the protective coating, in particular, effect of improving the oxidation resistance at the time of repeated oxidation, and further, contributes to grain boundary strengthening, the creep rupture strength and also it has a function of improving the creep rupture ductility. However, if the content of Sc exceeds 0.5%, inclusions are more becomes workability and weldability are impaired, such as oxides. Therefore, the amount of Sc in the case of containing a 0.5% or less. The upper limit of the Sc content is preferably set to 0.3%, 0.15% Tosureba more desirable. Meanwhile, in order to ensure the above-described effect of Sc is preferably set to 0.0005% the lower limit of the Sc content. In a more preferred lower limit is 0.001% of the Sc content, yet more preferably 0.002%.
[0069]
　The upper limit of the total content of the elements from the above Mg up to Sc may be 2.6%. The upper limit of the total content of the above is more preferably 1.5%.
[0070]
　Ta is an element of the group of <3>, Re, Ir, Pr, Pt and Ag have a solid solution strengthening effect by solid solution both a matrix austenite. Therefore, the solid solution strengthening effect therefore, added aggressively if it is desired to obtain a higher strength, one or more of these elements may be contained within the following range.
[0071]
　Ta: 8% or less
　Ta has as well as solid solution in austenite matrix, to form a carbonitride, an effect of improving the high temperature strength and creep rupture strength. Thus it may contain Ta in order to obtain these effects. However, if the content of Ta exceeds 8%, workability and mechanical properties are impaired. Therefore, to not more than 8% the amount of Ta in the case to be contained. The upper limit of the Ta content is preferably set to 7%, 6% Tosureba more desirable. Meanwhile, in order to ensure the above-described effect of the Ta is the lower limit of the Ta content is preferably set to 0.01%. 0.1% more preferred lower limit is the Ta content, yet more preferably 0.5%.
[0072]
　Re: 8% or less
　Re is a solid solution in the austenite matrix, because it has a function of improving the high temperature strength and creep rupture strength, may contain Re to obtain these effects. However, if the content of Re exceeds 8%, workability and mechanical properties are impaired. Therefore, to not more than 8% the amount of Re in the case of containing. The upper limit of the Re content is preferably set to 7%, 6% Tosureba more desirable. Meanwhile, in order to ensure the above-described effect of Re is a lower limit of the Re content is preferably set to 0.01%. 0.1% more preferred lower limit is the Re content, yet more preferably 0.5%.
[0073]
　Ir: 5% or less
　Ir, together with a solid solution in the austenite matrix, the part in accordance with the content has an effect of forming fine intermetallic compounds to improve high-temperature strength and creep rupture strength. Therefore, it may be contained Ir in order to obtain these effects. However, if the content of Ir is more than 5%, the workability and mechanical properties are impaired. Therefore, the amount of Ir in case of containing more than 5%. The upper limit of the Ir content is preferably set to 4%, 3% Tosureba more desirable. Meanwhile, in order to ensure the above-described effect of the Ir, the lower limit of the Ir content is preferably set to 0.01%. In a more preferred lower limit is 0.05% Ir content, yet more preferably 0.1%.
[0074]
　Pd: 5% or less
　Pd, together with a solid solution in the austenite matrix, the part in accordance with the content has an effect of forming fine intermetallic compounds to improve high-temperature strength and creep rupture strength. Therefore, it may contain Pd in order to obtain these effects. However, if the content of Pd is more than 5%, the workability and mechanical properties are impaired. Therefore, the amount of Pd in the case of containing more than 5%. The upper limit of the Pd content is preferably set to 4%, 3% Tosureba more desirable. Meanwhile, in order to ensure the above-described effect of Pd, the lower limit of the Pd content is preferably set to 0.01%. In a more preferred lower limit is 0.05% Pd content, yet more preferably 0.1%.
[0075]
　Pt: 5% or less
　Pt also with solid solution in austenite matrix, partially in response to the content to form a fine intermetallic compound, because it has a function of improving the high temperature strength and creep rupture strength, it may contain Pt in order to obtain these effects. However, when the content of Pt is more than 5%, the workability and mechanical properties are impaired. Therefore, the amount of Pt in the case of containing more than 5%. The upper limit of the Pt content is preferably set to 4%, 3% Tosureba more desirable. Meanwhile, in order to ensure the above-described effect of Pt, it is preferable that the lower limit of its content is 0.01%. In a more preferred lower limit is 0.05% Pt content, yet more preferably 0.1%.
[0076]
　Ag: 5% or less
　Ag, together with a solid solution in the austenite matrix, the part in accordance with the content has an effect of forming fine intermetallic compounds to improve high-temperature strength and creep rupture strength. Thus it may contain Ag in order to obtain these effects. However, if the Ag content exceeds 5%, the workability and mechanical properties are impaired. Therefore, the amount of Ag in the case of containing more than 5%. The upper limit of the Ag content is preferably set to 4%, 3% Tosureba more desirable. Meanwhile, in order to ensure the above-described effect of the Ag is the lower limit of the Ag content is preferably set to 0.01%. In a more preferred lower limit is 0.05% Ag content, yet more preferably 0.1%.
[0077]
　The total content of the element from above Ta to Ag is preferably 10% or less. The upper limit of the total content of said elements is more preferably 8%.
[0078]
　P ≦ 3 / {200 (Ti + 8.5 × Zr)}
　austenitic heat resistant alloy of the present invention, Ti, the content of Zr and P, respectively, in the ranges already mentioned, and,
P ≦ 3 / {200 (Ti + 8.5 × Zr)} ··· (1)
must satisfy the equation. This, Ti and Zr lower the melting point of the heat-resistant alloy, and because P decreases the hot workability, be in a range of Ti, the content of Zr and P already mentioned, the (1) If not satisfied expression, hot workability, in particular, reduces the hot workability at 1150 ° C. or more high temperature side, further, resistance to hot cracking during welding there is a decrease. However, Ti, the content of Zr and P are satisfies the above equation (1), in terms of maintaining high creep rupture strength, the hot workability of stably and reliably 1150 ° C. or more high temperature side can be improved, further, it is also possible to enhance the resistance to hot cracking during welding.
[0079]
　1.35 × Cr ≦ Ni ≦ 1.85 × Cr or,,
　1.35 × Cr ≦ Ni + Co ≦ 1.85 ×
　Cr content of Ni is in a range already mentioned, and the Cr content in
relation, 1.35 × Cr ≦ Ni ≦ 1.85 × Cr · · · (2)
meets the equation of the case containing in combination the Co, the content of Ni and Co, respectively, already mentioned in the range, and, in relation to the Cr
content, 1.35 × Cr ≦ Ni + Co ≦ 1.85 × Cr · · · (4)
by satisfying expression, stably and reliably prolonged use at high temperatures it is possible to suppress the σ phase precipitates in, moreover, it is possible to deposit the optimal amount of alpha-Cr phase. Accordingly, the austenitic heat resistant alloy of the present invention, it was decided to satisfy the above (2) or (4).
[0080]
　Al ≧ 1.5 × Zr
　austenitic heat resistant alloy of the present invention, each content of Al and Zr, in a range that already mentioned,
and, Al ≧ 1.5 × Zr · · · (3)
wherein the it is necessary to meet. This is also in a range in which the content of Al and Zr already mentioned, when not satisfy the above equation (3), the effect of improving the creep rupture strength by promoting the precipitation of alpha-Cr phase Zr This is because there is a case that can not be sufficiently secured. However, the content of Al and Zr, if not satisfy the equation (3) above, it is possible to obtain a stable and reliably to promote the precipitation of alpha-Cr phase Zr effect of enhancing the creep rupture strength.
[0081]
　Austenitic heat resistant alloy of the present invention as described above is excellent in structural stability and creep resistance. Therefore, if this austenitic heat resistant alloy as a material, the creep resistance and structural stability in high heat and pressure-resistant members in a high temperature range according to the present invention can be easily obtained. Incidentally, austenitic heat resistant alloy of the present invention as a material for the pressure-resistant member of the present invention may be melted and cast in the same way as ordinary austenitic alloy.
[0082]
　(B) method for producing a heat and pressure-resistant members
　will now be described preferred manufacturing method for obtaining a heat- and pressure-resistant member made of austenitic heat resistant alloy of the present invention. This manufacturing method previously described (i), characterized in that sequentially through the step of (ii) and (iii).
[0083]
　Step (i): before final processing by hot or cold, at least once, heating to 1050 ~ 1250 ° C.
　In the process of the present invention, prior to final machining by hot or cold, at least once performing heating, it is necessary to sufficiently solid solution precipitates precipitated in the alloy during processing. However, when the heating temperature is lower than 1050 ° C. is undissolved carbonitride or oxide containing a stable Ti and B will be present in the alloy after heating. As a result, it becomes a cause of accumulation of nonuniform strain in the next step (ii), the recrystallization nonuniform in the final heat treatment step (iii). Further, undissolved carbonitride or oxide itself would inhibit uniform recrystallization. On the other hand, when heated to temperatures above 1250 ° C., it can cause hot grain boundary cracking and ductility decrease. Therefore, in a preferred method of the present invention, prior to final machining by hot or cold, at least once, heating to 1050 ~ 1250 ° C.. A preferred lower limit is 1150 ° C., the upper limit is preferably 1230 ° C..
[0084]
　Step (ii): hot or a final plastic working of reduction of area of 10% or more by cold
　plastic working step (ii), the purpose of imparting strain in order to promote recrystallization in the next final heat treatment carried out in the. Reduction of area of the processing in the case of less than 10%, it is impossible to impart distortion required for recrystallization. Thus, plastic working is carried out at a cross-section reduction rate of 10% or more. The lower limit of the desired reduction of area is 20%. Although the upper limit is not specified because of the reduction of good larger, the maximum value in the normal processing is about 90%. Also, the machining process is also a process for determining the size of the product.
[0085]
　For final processing after heating to avoid uneven deformation at end temperature carbide precipitation temperature range of hot working in the case of hot working, preferably to 1000 ° C. or higher. Although there is no particular limitation on the cooling conditions after the processing, after hot working ends, in order to suppress the precipitation of coarse carbonitrides, temperature range of 0.25 ° C. / sec or more up to 500 ° C. it is desirable to cool as much as possible cooling rate.
[0086]
　If processing after the heating is cold working, cold working may be once a final may be performed plural times. When performing multiple times, the middle heat treatment after performing the cold working, but above step (i) of the heat treatment temperature and process (ii) cold working reduction of area of ​​at least the final cold working and the previous course of it may be satisfied by a heat treatment.
[0087]
　Step (iii): a final heat treatment of cooling after heating maintained at a temperature in the range of 1100 ~ 1250 ° C.
　If the heating temperature of the heat treatment is lower than 1100 ° C., does not occur sufficiently recrystallization. The crystal grains become flat processed structure, creep strength is lowered. On the other hand, when heated to temperatures above 1250 ° C., since it may cause high temperature grain boundary cracking and ductility decrease, temperature of the final product heat treatment, and 1100 ~ 1250 ° C.. A preferred thermal processing temperature is a temperature 10 ° C. or higher than the heating temperature in step (i).
[0088]
　Incidentally, heat- and pressure-resistant member of the present invention is not dare need to be fine tissue from the viewpoint of corrosion resistance, if you want to fine tissue, hot working finishing temperature from 10 ° C. or more lower temperature or above the middle, it may be performed final heat treatment at a temperature lower 10 ° C. or higher from the heat treatment temperature. After this final heat treatment, in order to suppress the precipitation of coarse carbonitrides, it is preferable to cool as much as possible cooling rate of more than 1 ° C. / sec.
[0089]
　The following examples illustrate the present invention more specifically, the present invention is not limited to these examples.
Example
[0090]
　Alloy 1 to 17 and A ~ K austenitic having the chemical compositions shown in Table 1 was melted by using a high-frequency vacuum melting furnace to obtain a 17kg ingot having an outer diameter of 100 mm.
[0091]
　Alloy in Tables 1 1 to 17, the chemical composition is an alloy which is in the range defined in the present invention. On the other hand, the alloy A ~ K, the chemical composition is an alloy of comparative example out of the range regulated by the present invention. Incidentally, both the alloy G and alloy H, although individual contents of Ni and Co is in the range defined in the present invention, an alloy which the value of "Ni + Co" does not satisfy the equation (4). Further, the alloy I, the content of Al that 0.03% is, although in the range of "0.01 to 0.3%" specified in the present invention, within the above (3) is not satisfied equation alloy . Furthermore, alloy K, the content of P of 0.009% is, although in the range of "0.03% or less" as defined in the present invention is an alloy that does not satisfy the equation (1).
[0092]
[Table 1]

[0093]
　Thus the ingot obtained, after heating to 1180 ° C., and hot forged to finishing temperature is 1050 ° C., was plate thickness 15 mm. It should be noted that, after the hot-forging the end, was air-cooled.
[0094]
　From the thickness direction center portion of each plate of the hot forging-obtained thickness 15mm above, parallel to the longitudinal direction, produced by machining a round rod tensile test specimen of 130mm length with 10mm in diameter, It was to evaluate the high-temperature ductility.
[0095]
　That is, a round bar tensile test specimen of the holding heated for 3 minutes to 1200 ° C., performs a fast tensile test at a strain rate of 10 / sec was determined aperture from the fracture surface after the test. If I have more than 60% of the aperture has been found that no particularly large problem even if the hot working such as hot extrusion at that temperature. Therefore, was to have 60% or more stop good hot workability criteria.
[0096]
　Further, by using a plate material having a thickness of 15mm, obtained by forging between the heat, after applying the softening heat treatment at 1100 ° C., and cold rolled to 10 mm, further cooled with water was held 30 minutes at 1200 ° C. .
[0097]
　Using a portion of each plate of thickness 10mm which is water cooled and held 30 minutes with the above 1200 ° C., in the thickness direction central portion, parallel to the longitudinal direction, the gauge length at 6mm diameter 30mm round the bar specimens were prepared by machining was performed creep rupture tests.
[0098]
　That is, using the above test pieces, 700 ° C., a creep rupture test conducted at 750 ° C. and 800 ° C. in the atmosphere, the resulting breaking strength and regression Larson-Miller parameter method, 700 ° C., 10000 hours a breaking strength of at were determined.
[0099]
　Furthermore, using each of the remaining plate thickness of 10mm which is water cooled and held for 30 minutes at the 1200 ° C., cooled with water from subjected to aging treatment of holding for 5000 hours at 750 ° C..
[0100]
　From the thickness direction center portion of each plate of 10mm thick water-cooled after the aging treatment described above, parallel to the longitudinal direction, according to JIS Z 2242 (2005), a width of 5 mm, is 55mm height length in 10mm to produce the V-notch test pieces subjected to Charpy impact test at 0 ° C., it was evaluated toughness by measuring the impact value.
[0101]
　Table 2 shows to organize the test results.
[0102]
[Table 2]

[0103]
　From Table 2, when the alloy 1-17 Test Nos. 1 to 17 used in the present invention embodiment, it is apparent that the creep rupture strength, in all of toughness and hot workability after aging is good.
[0104]
　In contrast, when the alloy A ~ Test No. 18 to 28 using a K of comparative examples out of the range regulated by the present invention, as compared with the case of the present invention examples of the above test numbers 1 to 17, Creep breaking strength, of the toughness and hot workability after aging are inferior at least one characteristic.
[0105]
　That is, in the case of Test No. 18, the alloy A, except that it does not contain the Zr, but has basically the same chemical composition as the alloy 2 used in test No. 2, a low creep rupture strength.
[0106]
　For Test No. 19, the alloy B, except that it does not contain a Ti, but has basically the same chemical composition as the alloy 2 used in test No. 2, a low creep rupture strength.
[0107]
　For Test No. 20, the alloy C is the W content is 2.7%, except that lower than the value specified in the present invention, and has basically the same chemical composition as the alloy 1 used in Test No. 1 there, but low creep rupture strength.
[0108]
　For Test No. 21, the alloy D is the N content is 0.024%, except that higher than the value specified in the present invention, and has basically the same chemical composition as the alloy 2 used in test No. 2 there, but low creep rupture strength.
[0109]
　For Test No. 22, the alloy E does not contain W, further, in the content of Mo is 2.5%, except that higher than the value specified in the present invention, the alloy 2 used in test No. 2 substantially has the same chemical composition, the creep rupture strength is low and a Charpy impact value after aging is also inferior significantly lower toughness.
[0110]
　For Test No. 23, as has been said conventionally, about half effect of the W is Mo, that is, if the W content corresponds to Mo content of about 1/2, the alloy F is Test No. 2 an alloy 2 equivalent alloy used in. However, the content of Mo in the alloy F is 2.2%, exceeding the values ​​specified in the present invention. Therefore, creep rupture strength is low, furthermore, is inferior to the extremely low toughness Charpy impact value after aging.
[0111]
　For Test No. 24, the alloy G is the sum of the contents of Ni and Co, that is, except that does not meet the "Ni + Co" value of less than "1.35 × Cr" (4) equation, Test No. 5 has substantially the same chemical composition as the alloy 5 used in the creep rupture strength is low and a Charpy impact value after aging is also inferior significantly lower toughness.
[0112]
　For Test No. 25, the alloy H is the sum of the contents of Ni and Co, that is, except that the value of "Ni + Co" does not satisfy the high (4) than "1.85 × Cr" is Test No. 5 substantially it has the same chemical composition, a low creep rupture strength and alloy 5 used in.
[0113]
　For Test No. 26, the alloy I, except that the content of Al does not satisfy the lower than (3) "1.5 × Zr", almost the same chemical composition as the alloy 2 used in test No. 2 It has, but low creep rupture strength.
[0114]
　For Test No. 27, the alloy J is the content of Al 0.64% except higher than the value specified in the present invention has substantially the same chemical composition as the alloy 2 used in test No. 2 and that although, Charpy impact value after aging are inferior in toughness low and, also hot workability does not stop reaches 60% at 1200 ° C. lower.
[0115]
　For Test No. 28, the alloy K, except that the content of P does not satisfy the "3 / {200 (Ti + 8.5Zr)}" Beyond (1) is an alloy 5 used in Test No. 5 It has substantially the same chemical composition, is significantly lower hot workability aperture at 50.2% at 1200 ° C..
Industrial Applicability

[0116]
　Austenitic heat resistant alloy of the present invention has excellent high-temperature strength than the conventional heat-resistant alloys, among others, which has a creep rupture strength, and toughness was good because a long time is excellent in structural stability and used at high temperatures further hot workability, in particular, excellent high temperature ductility at 1150 ° C. or higher. Therefore, power boiler, chemical industry pipe in the plant, such as material, a plate material of heat- and pressure-resistant member, bar, can be suitably used as a forging Hinto.
The scope of the claims

[Claim 1]
　By mass%, C: 0.02% 0.15% beyond less, Si: 2% or less, Mn: 3% or less, P: 0.03% or less, S: 0.01% or less, Cr: 28 ~ 38%, Ni: 60% over 40% or less, W: 15% more than 3% or less, Ti: 0.05 ~ 1.0%, Zr: 0.005 ~ 0.2%, Al: and 0.01 to 0.3% and, N: 0.02% or less, Mo: less than 0.5%, the balance being Fe and impurities, further the following (1) - (3 ) austenitic heat resistant alloy which satisfies the equation.
　≦ 3 P / {200 (Ti + 8.5 × Zr)} · · ·
　(1) 1.35 × Cr ≦ Ni ≦ 1.85 × Cr · · ·
　(2) Al ≧ 1.5 × Zr · · · ( 3)
　in addition, element symbol in the formulas represents the content by mass percent of the element.
[Claim 2]
　By mass%, C: 0.02% 0.15% beyond less, Si: 2% or less, Mn: 3% or less, P: 0.03% or less, S: 0.01% or less, Cr: 28 ~ 38%, Ni: 60% over 40% or less, Co: 20% or less, W: 15% more than 3% or less, Ti: 0.05 ~ 1.0%, Zr: 0.005 ~ 0 .2% Al: contains 0.01 to 0.3% and, N: 0.02% or less, Mo: less than 0.5%, the balance being Fe and impurities, further, the following (1), (3) and (4) austenitic heat resistant alloy which satisfies the equation.
　≦ 3 P / {200 (Ti + 8.5 × Zr)} · · ·
　(1) 1.35 × Cr ≦ Ni + Co ≦ 1.85 × Cr · · ·
　(4) Al ≧ 1.5 × Zr · · · ( 3)
　in addition, element symbol in the formulas represents the content by mass percent of the element.
[Claim 3]
　In mass%, further <1> to austenitic according to claim 1 or 2, characterized in that it contains one or more elements belonging to one or more groups selected from the group of <3> below heat-resistant alloy.
　<1> Nb: 1.0% or less, V: 1.5% or less, Hf: 1% or less and B: 0.05% or less
　<2> Mg: 0.05% or less, Ca: 0.05% or less , Y: 0.5% or less, La: 0.5% or less, Ce: 0.5% or less, Nd: 0.5% or less and Sc: 0.5% or less
　<3> Ta: 8% or less, Re : 8% or less, Ir: 5% or less, Pd: 5% or less, Pt: 5% or less and Ag: 5% or less
[Claim 4]
　Creep resistance and structural stability in high heat and pressure-resistant members in a high temperature range, characterized in that it consists of austenitic heat resistant alloy according to any one of claims 1 to 3.
[Claim 5]
　The austenitic heat resistant alloy according to any one of claims 1 to 3, the following steps (i), a high temperature range according to claim 4, characterized in that the sequential treatment with (ii) and (iii) the method for producing the creep resistance and structural stability in high heat and pressure-resistant member.
　Step (i): before final processing by hot or cold, at least once, heating to 1050 ~ 1250 ° C..
　Step (ii): a final plastic working of reduction of area of 10% or more by hot or cold.
　Step (iii): a final heat treatment of cooling after heating maintained at a temperature in the range of 1100 ~ 1250 ° C..