Art
[1]
The present invention relates to an austenitic stainless steel work piece, and that relates to a process for the preparation thereof, and more particularly to austenitic stainless steel work piece having excellent surface properties and methods for their preparation.
BACKGROUND
[2]
The present invention relates to a stainless steel workpiece is used as the sink, etc., and more particularly, that the surface defects such as protrusions on the surface, stripe after processing defect is no occurrence of cracks or the like after the processing in as synchronized processing occurring workability and the surface characteristics related to quality austenitic stainless steel workpieces.
[3]
Sink Bowl Kitchen Sink are generally made of stainless steel is used. It is mainly used by a specific general-purpose stainless steel, a shape of a typical sink bowl has no problem in forming a piece which is widely used.
[4]
However, an attempt to design the sink bowl recent variety of complex shapes in order to strengthen the competitiveness of the market has been increased.
[5]
Nitro-based austenite stainless steel material poor formability in steel molding generates defects such as cracks after the processing. There is also a case where a bad surface property being a projection formed on the surface, etc. after processing. It may cause a drop in the production yield in the working poor that when defects such as cracks, and requires additional processes such as polishing of the surface Poor surface characteristics arises a problem of increasing the cost of production.
[6]
For example a type of steel is widely used for processing of a sink, such as the prior art, the STS 304 steel, but the above-described processing cracks and surface deterioration acts as a persistent problem which often occurs.
[7]
Patent Document 1: Republic of Korea Patent Publication No. 10-2013-0014069 Document No.
Detailed Description of the Invention
SUMMARY
[8]
Embodiments of the present invention to provide a sink such as a complicated shape, even if machining machining cracks and surface deterioration does not occur, the surface properties are excellent austenitic stainless steel workpiece and a method.
Problem solving means
[9]
This is an excellent austenitic stainless steel work piece surface properties according to one embodiment of the present invention, by weight%, C: 0.005 to 0.15%, Si: 0.1 to 1.0%, Mn: 0.1 to 2.0%, Ni: 6.0 to 8.0 %, Cr: 16 to 18%, Cu: 0.1 to 4.0%, N: 0.005 to 0.2%, Mo: 0.01 to 0.2%, the rest to, and including an austenitic stainless steel of Fe and unavoidable contain impurities formula (1), with a part piece Ni surface stones in the range of 0.6 to 0.9 of which it is defined as a fraction of the martensite 10% to 30%.
[10]
(C -Min ) / (C -Ave ) ...... 식 (1)
[11]
Here, C Ni -Min is the minimum concentration of Ni in the surface, C Ni -Ave is the average Ni concentration at the surface.
[12]
Further, according to one embodiment of the present invention, it may be a surface hardness ratio range of 1.1 to 1.6, which is defined by the following formula (2).
[13]
A / B ... ... Formula (2)
[14]
Here, A is the average of the top 10% of the surface hardness of the workpiece, B is the average value of the workpiece surface hardness of the bottom 10%.
[15]
Further, according to one embodiment of the present invention, the crack is less than the depth from the surface 20㎛ be up to 10.
[16]
Further, according to one embodiment of the present invention, is less than 60% of Ni surface side seokbu the area fraction, Ni surface part piece seokbu may be greater than 5% in area fraction.
[17]
Production method of the present embodiment is excellent austenitic stainless steel workpiece surface characteristics according to the invention is, in weight%, C: 0.005 to 0.15%, Si: 0.1 to 1.0%, Mn: 0.1 to 2.0%, Ni: 6.0 to 8.0%, Cr: 16 to 18%, Cu: 0.1 to 4.0%, N: 0.005 to 0.2%, Mo: 0.01 to 0.2%, and the rest for machining the austenitic stainless steel containing Fe and inevitable impurities step, and a step of cooling within 30 minutes of the austenitic stainless steel comprising: heat-treated for 10 minutes or less, and heat-treating the above austenitic stainless steel work piece at a temperature of the workpiece 900 to 1,150 ℃ to 500 ℃.
[18]
Further, according to one embodiment of the invention, before heat treatment, the martensite fraction of the austenitic stainless steel work piece may be a 10 to 50%.
[19]
Further, according to one embodiment of the invention, the fraction of martensite after cooling, the austenitic stainless steel work piece may be a 10 to 30%.
Effects of the Invention
[20]
Austenitic stainless steel processed according to embodiments of the present invention, even when processed into a complicated shape to the sink, etc. it is possible to prevent defects such as processing crack, prevent surface defects such as protrusions to streaks generated on the surface after processing can do.
Brief Description of the Drawings
[21]
Figure 1 is a photo photographed the Ni piece seokbu seokbu and part piece are formed on the surface of an austenitic stainless steel work piece in accordance with one embodiment of the present invention.
[22]
Figure 2 is a picture taken of the surface of a conventional austenitic stainless steel workpieces.
[23]
3 is a photograph taken of the surface of an austenitic stainless steel work piece in accordance with one embodiment of the present invention.
[24]
Figure 4 is a photograph taken of the surface of an austenitic stainless steel work piece according to the comparative example of the present invention.
[25]
Figure 5 is a picture taking a machined surface of a machined workpiece sink in a conventional austenitic stainless steel.
[26]
Figure 6 is a picture taking a processing surface of a processing sink in austenitic stainless steel according to one embodiment of the invention the work piece.
[27]
Figure 7 is a picture taking a surface crack in the austenite-based stainless steel nitro processed according to a comparative example of the present invention.
[28]
8 is a graph for explaining a method for manufacturing the austenitic stainless steel according to one embodiment of the present invention.
Best Mode for Carrying Out the Invention
[29]
This is an excellent austenitic stainless steel work piece surface properties according to one embodiment of the present invention, by weight%, C: 0.005 to 0.15%, Si: 0.1 to 1.0%, Mn: 0.1 to 2.0%, Ni: 6.0 to 8.0 %, Cr: 16 to 18%, Cu: 0.1 to 4.0%, N: 0.005 to 0.2%, Mo: 0.01 to 0.2%, the rest to, and including an austenitic stainless steel of Fe and unavoidable contain impurities formula (1), with a part piece Ni surface stones in the range of 0.6 to 0.9 of which it is defined as a fraction of the martensite 10% to 30%.
[30]
(C -Min ) / (C -Ave ) ...... 식 (1)
[31]
Here, C Ni -Min is the minimum concentration of Ni in the surface, C Ni -Ave is the average Ni concentration at the surface.
Mode for the Invention
[32]
Hereinafter will be described in detail with reference to the accompanying drawings, an embodiment of the present invention. The following examples will be presented to fully convey the scope of the invention to those of ordinary skill in the art. The present invention is not limited to the embodiments described herein may be embodied in different forms. Figures may be somewhat exaggerated to express the size of the components, for clarity, not shown, and a portion not related to the description in order to clarify the invention.
[33]
This is an excellent austenitic stainless steel work piece surface properties according to one embodiment of the present invention, by weight%, C: 0.005 to 0.15%, Si: 0.1 to 1.0%, Mn: 0.1 to 2.0%, Ni: 6.0 to 8.0 %, Cr: 0.01 to 0.2% and the remainder including an austenitic stainless steel which comprises Fe and inevitable impurities: from 16 to 18%, Cu: 0.1 to 4.0%, N: 0.005 to 0.2%, Mo. That is, the workpiece can be manufactured by processing the stainless steel, the workpiece may be, for example, the sink bowl (bowl sink).
[34]
In the following, a description will be given of the reason for numerical limitation of the components constituting the formability and surface properties are excellent austenitic stainless steel of the present invention.
[35]
C is added to adjust within a range from 0.005 to 0.15% by weight.
[36]
C is the austenite phase is the more stable austenite phase is added as a stabilizing element containing one or more than 0.005%, if excessively contained, because the strength can be difficult to over-higher processing is limited to not more than 0.15%.
[37]
Si is added to adjust within a range of 0.1 to 1.0% by weight.
[38]
Si is added more they provide the effect of a certain level of work hardening and corrosion resistance containing one, adding too much over 0.1%, it is possible to inhibit the toughness will be limited to less than 1.0%.
[39]
Mn is added to adjust within a range of 0.1 to 2.0% by weight.
[40]
Mn is limited to 2.0% or less because the corrosion inhibition when austenite phase to stabilize the more is added as an austenite stabilizing element, and the excessive addition of one, less than 0.1% it is effective to reduce the work hardening rate.
[41]
Ni is added by controlled within 6.0 to 8.0% by weight.
[42]
Ni are austenite addition of nitro onto the more added as a stabilizing element and stabilizes austenite phase has the effect that the addition amount increases and the austenite reducing the river softening and work hardening rate, because it is an element that forms a part seokdae in the present invention at least 6.0% One, if you added a lot of leads to increase in cost, so is limited to 8.0%.
[43]
Cr is added by controlled within 16 to 18% by weight.
[44]
Cr is one containing more than 16% as an element for improving the corrosion resistance, since the excessive addition is accompanied by an increase in cost will be limited to 18%.
[45]
Cu is added to adjust within a range of 0.1 to 4.0% by weight.
[46]
Cu are austenite phase to stabilize the more added as a stabilizing element austenite phase, and it is effective to reduce the softening and work hardening rate Austenitic Steels and less than 0.1%, the amount added is contained to increase the austenite phase to stabilize in the present invention this characteristic is obtained in pursuit can be added even 4.0%. However, since excessive addition of Cu is accompanied by an increase in cost it is preferably limited to 2.0%.
[47]
N is added to adjust within a range from 0.005 to 0.2% by weight.
[48]
N is the more austenite phase is added as a stabilizing element to stabilize austenite phase to improve corrosion resistance, because one contains not less than 0.005%, if excessively contained, the strength may be difficult to process because excessively increased is limited to 0.2% or less.
[49]
Mo is added to adjust within a range of 0.01 to 0.2% by weight.
[50]
Mo has got the effect of improving the corrosion resistance and workability containing one or not less than 0.01%, since the excessive addition is accompanied by an increase in cost will be limited to less than 0.2%.
[51]
Figure 1 is a photo photographed the Ni piece seokbu seokbu and part piece are formed on the surface of an austenitic stainless steel work piece in accordance with one embodiment of the present invention. Figure 2 is a picture taken of the surface of a conventional austenitic stainless steel workpieces. 3 is a photograph taken of the surface of an austenitic stainless steel work piece in accordance with one embodiment of the present invention.
[52]
1, the formability and surface properties are excellent austenitic stainless steel workpiece according to one embodiment of the present invention includes the Ni surface side surface part piece seokbu seokbu and Ni on the steel surface.
[53]
That is, the austenitic stainless steel workpiece according to one embodiment of the present invention, the surface part piece seats of Ni, which is defined by the following formula (1) in the range of 0.6 to 0.9.
[54]
(C -Min ) / (C -Ave ) ...... 식 (1)
[55]
Here, C Ni -Min is the minimum concentration of Ni in the surface, C Ni -Ave is the average Ni concentration at the surface.
[56]
Tin surface part piece of Ni is defined by the formula (1), a value obtained by dividing the minimum concentration of Ni in the steel surface in an average concentration of Ni, the minimum concentration of Ni is the measured value in the Ni seokbu part piece.
[57]
Here, the side seats is measured from the surface of the stainless steel work piece. Statistically in order to have the means 500 500㎛ * 2 measured at the above area, and is preferably measured at 50 or more locations with equal spacing on each axis.
[58]
Measurement method may take advantage of the energy dispersive spectroscopic analysis (energy dispersive spectroscopy, EDS) or EM trace analysis (electron probe micro analysis, EPMA) or the like.
[59]
According to the present invention 800 * 800㎛ 2 was utilizing EPMA in the stainless steel the source surface in the area of the measuring element distribution of Ni, it is shown in Fig. The light-colored in Fig. 1 means the Ni seokbu part piece, and the dark color represents Ni and Pt seokbu, it can be seen that the formed piece seokdae.
[60]
2, a picture taken of the work piece surface of the STS 301 steel processed using a conventional austenitic stainless steel. This is a steel that is not formed with a Ni piece on the surface of an austenitic stainless steel work piece and seokbu seokbu part piece, the surface properties of the surface roughness shows a degraded by a projection generated on the surface of the processed products thereof.
[61]
When Alternatively, referring to Figure 3, and taking a surface of austenitic stainless steel workpiece according to one embodiment of the invention picture. Which it is formed with a side surface of Ni on the surface of austenitic stainless steel and Ni seokbu workpiece surface seokbu part piece, even if the part can be seen does not have any streaks or projections on the surface has a graceful surface quality.
[62]
The present inventors with respect to the effect of the Ni surface side seokbu that when processing a formed stainless steel, a martensitic transformation from part piece seokbu during processing in case the material also contains the same amount of Ni does not form a part seokbu much consist of projections It is assumed to be formed is suppressed.
[63]
Figure 4 is a photograph taken of the surface of an austenitic stainless steel work piece according to the comparative example of the present invention.
[64]
If the surface of the part piece Tin Ni is less than 0.6, it is formed in the side seokdae excessively on the surface there is a problem in that severe streaking along the rolling direction on the surface after machining. 4, the surface part piece seats of the Ni in the recorded pictures of the surface after machining austenitic stainless steel having a 0.5, it can be seen that the stripes observed in the rolling direction, the surface defects caused by such streaks the need for additional processes such as polishing of the surface, thereby increasing the production cost.
[65]
Further, when the surface of the part piece Tin Ni is in excess of 0.9, the amount of small pieces and seokbu seokbu part piece is either not formed in the form of interest in the present invention does not achieve the martensitic transformation of the part piece seokbu.
[66]
Further, the martensite fraction is in the austenitic stainless steel workpiece according to one embodiment of the invention 10 to 30%.
[67]
If the martensite fraction of the processed products in 30% excess, more there is a problem that cracks are generated during processing, when the martensite fraction of the processed products in the range of 10 to 30% of wrinkles in the crack to the surface even during further processing occurs I never do that.
[68]
For example, the austenite the Ni surface side seokbu knight-based stainless steel work piece is less than 60% in area fraction, the Ni surface part piece seokbu may be greater than 5% in area fraction.
[69]
The Ni surface side seokbu is large Ni concentrated area than the average concentration of Ni in the surface, the surface Ni seokbu part piece is a small Ni Ni depletion region than average concentration at the surface. For example, the Ni thickening area has more than 1.2 times the Ni concentration than the average concentration of Ni in the surface, it said Ni-deficient region can have a Ni concentration of less than 0.8 times the mean concentration of Ni in the surface.
[70]
Such a Ni surface part piece or seokbu form the in the austenitic area fraction on the stainless steel surface to no more than 5%, the Ni surface side when seokbu is formed by more than 60% in area fraction, the processing when the Ni surface part piece a martensitic transformation from seokbu mothayeo sufficiently made difficult to suppress the projection on the surface after machining.
[71]
For example, the Ni surface seokbu part piece may include a long diameter of not less than 100㎛ segregation more than 60%. Accordingly, as the Ni surface part piece finely divided my seokbu segregation, as the segregation size is increased it is possible to prevent the streaks occur along the rolling direction on the surface after processing it is possible to improve the surface properties.
[72]
For example, the austenitic stainless steel workpiece according to one embodiment of the present invention may be a surface hardness ratio range of 1.1 to 1.6, which is defined by the following formula (2).
[73]
A / B ... ... Formula (2)
[74]
Here, A is the average of the top 10% of the surface hardness of the workpiece, B is the average value of the workpiece surface hardness of the bottom 10%.
[75]
The measurement of surface hardness, in order to have a statistically significant is preferably measured at 50 or more locations in the 10 mm range for each direction to a cross direction. For example, if the value obtained by dividing the average value of the surface hardness of the top 5 to the lower five average value may be a surface hardness ratio.
[76]
The hardness ratio is less than 1.1, a piece seokbu and part piece seokbu on the surface of the work piece or be formed small amount of the form was the amount of martensitic transformation of the part piece seokbu relatively small, whereby the surface of the austenitic stainless steel workpieces the protrusions exist, and the, there is a problem that a wrinkle on the surface during further processing thereof occurs.
[77]
If the surface hardness ratio of 1.6 is exceeded, is formed in the side seokdae excessively on the surface of the workpiece appears severe stripes along the direction of rolling austenite stainless steel, the surface of the work piece, there is a problem that a crack when adding its processing occurs.
[78]
Figure 5 is a picture taking a machined surface of a machined workpiece sink in a conventional austenitic stainless steel. Figure 6 is a picture taking a processing surface of a processing sink in austenitic stainless steel according to one embodiment of the invention the work piece. Figure 7 is a picture taking a surface crack in the austenite-based stainless steel nitro processed according to a comparative example of the present invention.
[79]
For example, the austenitic stainless steel workpiece according to one embodiment of the present invention can be up to 10 or more cracks of a depth from the surface 20㎛. When the crack than the depth from the surface of the workpiece 20㎛ than 10 is determined as defective in the workpiece can be used is limited.
[80]
Referring to FIGS. 5 and 7, to observe the work piece in STS surface of 301 steel processed using a conventional austenitic stainless steel, austenitic stainless steel, severe surface cracking during processing and to find out balsaengdoem, therefore, an austenitic stainless steel work piece presenting the present invention is found to be excellent in workability, such as a sink 6, for example.
[81]
Production method of the present embodiment is excellent austenitic stainless steel workpiece surface characteristics according to the invention is, in weight%, C: 0.005 to 0.15%, Si: 0.1 to 1.0%, Mn: 0.1 to 2.0%, Ni: 6.0 to 8.0%, Cr: 16 to 18%, Cu: 0.1 to 4.0%, N: 0.005 to 0.2%, Mo: 0.01 to 0.2%, and the rest for machining the austenitic stainless steel containing Fe and inevitable impurities step, and a step of cooling within 30 minutes of the austenitic stainless steel comprising: heat-treated for 10 minutes or less, and heat-treating the above austenitic stainless steel work piece at a temperature of the workpiece 900 to 1,150 ℃ to 500 ℃.
[82]
8 is a graph for explaining a method for manufacturing the austenitic stainless steel according to one embodiment of the present invention.
[83]
In Figure 8, the can and the weight% The austenitic stainless steel, C: 0.005 to 0.15%, Si: 0.1 to 1.0%, Mn: 0.1 to 2.0%, Ni: 6.0 to 8.0%, Cr: 16 to 18%, Cu: 0.1 to 4.0%, N: 0.005 to 0.2%, Mo: 0.01 to 0.2%, and the remainder can be produced austenitic stainless steel which comprises Fe and unavoidable impurities to continuous casting.
[84]
In this case, the continuous casting step, the cast steel in the second from the cooling units, 1,150 to 1,200 ℃ in the step of cooling the cast steel in the first temperature range by more than 60 ℃ / min speed, 900 to 1,150 ℃ in a second temperature range the slab in steps and not more than 900 ℃ third temperature range, cooling at a rate of less than 10 ℃ / min and a step of cooling of at least 20 ℃ / min rate.
[85]
The continuously cast slab is subjected to a step of cooling the cast slab to at least 60 ℃ / min rate at a first temperature range of 1,150 to 1,200 ℃.
[86]
To the continuous casting from the molten steel having a component system of the present invention produced a slab, in this case to form the Ni surface side seokbu and Ni surface part piece seokbu on the cast surface in the first temperature range and performs the cast quenched . In this case, for example, it is done by a cast full face through the front nozzle spray to cool rapidly. If Alternatively, the main side on which the first cooling at a rate of less than 60 ℃ / min in the first temperature range may not be formed in the Ni surface side seokbu and seokbu part piece to the surface.
[87]
Typically, but known seat Ni segregation cast center part of the continuous casting, when performing rapid cooling at a constant temperature intervals as in the present invention, it is possible to form the Ni segregation in the slab surface.
[88]
Accordingly, the austenitic stainless steel according to one embodiment of the invention the surface of the part piece Tin Ni represented by the formula (1) may satisfy the range of 0.6 to 0.9.
[89]
Thereafter, go through the step of cooling the cast steel at a second temperature range of 900 to 1,150 ℃ at a rate of less than 10 ℃ / min.
[90]
In the first after the formation of the Ni segregation to the surface at a temperature interval, wherein the second temperature ranges to perform slow cooling convenience the state. Accordingly, some of the Ni segregation of the slab surface is to be re-employed.
[91]
Accordingly, the austenitic stainless steel Ni seokbu surface side is less than 60% in area fraction, Ni surface part piece seokbu may satisfy more than 5% in area fraction.
[92]
Thereafter, go through the step of cooling the cast steel at not more than 900 ℃ third temperature range of at least 20 ℃ / min rate.
[93]
In the first re-employed after the Ni segregation part to the surface in the second temperature range, wherein the third temperature interval and performs the rapid cooling the cast. Accordingly, it is possible to refine the segregation in the Ni surface seokbu part piece of the product surface.
[94]
Then, a step and a step of cold rolling the hot rolled slab to hot rolling the slab cooling in the secondary cooling stage.
[95]
At this time, the re-heating is performed within five hours of hot rolling during continuous casting of austenitic stainless steel slabs. When the re-heating time of the slab for more than five hours, the formed on the surface of Ni surface side seokbu and part piece not seokbu can begins to decompose satisfy the Ni surface part piece seokbu and the Ni surface side monument on the surface of interest in the present invention do.
[96]
In addition, after annealing the hot-rolled or cold-rolled and annealed hours, raising the temperature to the annealing temperature of 1,000 to 1,200 ℃ less than 30 seconds, the holding time is carried out within 30 seconds. When hot-rolled and annealed or cold-rolled and annealed with increasing the temperature rising time and holding time, that the Ni surface side seokbu and part piece seokbu formed on the surface starts to be decomposed by the Ni surface part piece seokbu and the Ni surface side monument on the surface of interest in the present invention It can not be satisfied.
[97]
Thereafter, the heat treatment after machining the austenitic stainless steels, the austenitic stainless steel work piece at a temperature of 900 to 1,150 ℃ for less than 10 minutes. And it performs the heat treatment of the work piece in order to control the surface side seokdae, and hardness ratio of martensite fraction of the work piece.
[98]
For example, before heat treatment, the martensite fraction of the austenitic stainless steel work piece may be a 10 to 50%.
[99]
The heat treatment of 900 and is performed at a temperature of 1,150 ℃ in 10 minutes or less, if the heat treatment temperature is lower than 900 ℃ difficult to reduce the fraction of the modified organic martensite, or the heat treatment temperature exceeds 1,150 ℃, the heat treatment time exceeds 10 minutes case, the surface of the Ni piece seokbu seokbu and part piece are formed on the surface starts to be decomposed can not be satisfied by the Ni surface part piece stones, the surface ratio of the surface hardness desired in the present invention.
[100]
Thereafter, a heat treatment wherein the austenitic stainless steel workpiece up to 500 ℃ is cooled within 30 minutes. It performs the rapid cooling process of the work piece in order to refine the surface segregation in the Ni seokbu part piece of the work piece.
[101]
Wherein the heat treatment wherein the austenitic stainless steel workpiece can be cooled by air cooling or water cooling and, thus, it is possible to refine the segregation in the Ni surface seokbu part piece of the work piece surface.
[102]
For example, the Ni surface seokbu part piece may include a long diameter of not less than 100㎛ segregation more than 60%. Accordingly, as the Ni surface part piece finely divided my seokbu segregation, it is possible to prevent the streaks generated on the surface after the further processing in accordance with the segregation size is increased it is possible to improve the surface properties.
[103]
For example, after cooling, the martensite fraction of the austenitic stainless steel work piece may be a 10 to 30%.
[104]
[105]
The present invention through the following examples to be described in more detail.
[106]
Example
[107]
To an austenitic stainless steel slab containing Examples 1 to 9, and the components of the Comparative Examples 1 to 6 shown in Table 1 were prepared by continuous casting. Then, after the cold rolling to the hot-rolling, and a total rolling reduction of 50% to prepare a cold-rolled steel sheet.
[108]
Next, the Examples 1 to 9 and Comparative Examples 1 to the martensite content of the cold-rolled steel sheet with a diameter of 150mm is spherical punch of 6 after processing so that 40%, 30 seconds after the temperature of the workpiece reached the 1,100 ℃ heat treatment then it cooled to 2 minutes of air cooling up to 500 ℃. Since the workability was observed after further processing.
[109]
TABLE 1
C And Mn Ni Cr With you N
Examples 1 0.115 0.6 0.2 6.8 17.3 0.61 0.19 0.05
To honor two 0.109 0.6 0.8 6.7 17.2 0.59 0.14 0.05
To honor 3 0.108 0.2 1.6 6.7 17.2 1.00 0.09 0.05
To honor four 0.108 0.9 1.9 6.7 16.2 1.60 0.09 0.05
To honor five 0.108 0.6 0.9 9.8 19.6 1.00 0.09 0.05
To honor 6 0.108 0.6 1.0 6.6 17.2 0.12 0.04 0.04
To honor 7 0.009 0.6 0.9 6.6 17.2 2.05 0.04 0.14
To honor eight 0.115 0.6 0.9 6.6 17.2 2.94 0.04 0.04
To honor nine 0.115 0.6 0.9 6.1 17.2 3.90 0.01 0.04
Comparative Example 1 0.110 0.6 0.9 6.7 17.0 0.25 0.12 0.04
Comparative Example 2 0.113 0.6 0.9 6.7 17.2 0.00 0.04 0.04
Comparative Example 3 0.110 0.6 0.8 6.6 17.2 0.05 0.04 0.04
Comparative Example 4 0.115 0.6 0.9 5.8 17.2 1.00 0.01 0.04
Comparative Example 5 0.111 0.6 0.9 7.0 18.0 0.01 0.04 0.04
Comparative Example 6 0.060 0.6 0.9 8.5 19.2 0.01 0.01 0.04

[110]
Thus of the workpiece produced according Ni surface part piece seats, the martensite fraction, surface hardness ratio, surface properties, and additional post-processing to observe whether cracks to occur wrinkles to the naked eye are shown in Table 2 below.
[111]
TABLE 2
Ni surface part piece Tin Martensite fraction (%) Surface hardness ratio Surface Properties Workability
Examples 1 0.90 19.0 1.2 Good Good
To honor two 0.67 23.0 1.5 Good Good
To honor 3 0.90 21.0 1.1 Good Good
To honor four 0.63 15.0 1.5 Good Good
To honor five 0.71 10.0 1.4 Good Good
To honor 6 0.67 28.0 1.5 Good Good
To honor 7 0.83 18.0 1.2 Good Good
To honor eight 0.90 13.0 1.2 Good Good
To honor nine 0.90 14.0 1.1 Good Good
Comparative Example 1 0.53 35.0 2.2 stripe crack
Comparative Example 2 0.59 32.0 1.7 stripe crack
Comparative Example 3 0.56 40.0 1.9 stripe crack
Comparative Example 4 0.45 45.0 2.2 stripe crack
Comparative Example 5 1.00 16.0 1.0 spin wrinkle
Comparative Example 6 1.00 15.0 1.0 spin wrinkle

[112]
Here, Ni surface part piece seats and surface hardness ratio is measured at the surface of an austenitic stainless steel piece.
[113]
Statistically in order to have the means 500 * 500㎛ 2 is measured in the area more, it is preferable to measure at more than 50 locations at equal intervals on each shaft
[114]
When the measuring surface is that the number and, to the polishing surface as a source surface, the abrasive it is preferred that the particle size of the abrasive or less 2㎛. Measurement method may take advantage of the energy dispersive spectroscopic analysis (energy dispersive spectroscopy, EDS) or EM trace analysis (electron probe micro analysis, EPMA) or the like.
[115]
In the present invention, the Ni-up of element distribution by EPMA method 800㎛ * 800㎛ area. Stainless steel is generally so to form a layer on the surface was measured in a reaction volume as the device can have when it is not sufficient 200㎛ the oxide to 1 from the surface to be polished to measure the area of ​​the oxide layer below surface which measures the element. In addition, foreign matter is nonoe of the present invention was that of the base metal Ni segregation.
[116]
Referring to Table 1 and Table 2, if they meet the component and the range of austenitic stainless steel workpiece according to one embodiment of the present invention, it can be seen that the surface properties and excellent formability. However, the processability surface properties to be seen in order to open the case, even if these components satisfy the ranges that do not meet the seats Ni part piece of the steel surface and the surface hardness.
[117]
[118]
The results of observing the number of cracks not less than the depth from the 20㎛ After addition, the further processing of the Examples 1 to 3 and Comparative Examples 1 to 3, the surface shown in Table 3 below.
[119]
TABLE 3
Number of cracks during further processing (ea)
Examples 1 1
To honor two 2
To honor 3 8
Comparative Example 1 15
Comparative Example 2 50
Comparative Example 3 20

[120]
Referring to Table 3, and the number of cracks not less than the depth from the surface 20㎛ generated during further processing of the austenitic stainless steel processed according to embodiments of the invention found to be satisfactory in workability with less than 10 , according to the comparative example by the number of cracks not less than the depth from the surface 20㎛ than 10 it can be seen that in order processability the heat generated in a large amount.
[121]
In the above-described bar, although the description has been made to exemplary embodiments of the present invention, in the present invention is not limited to those skilled in the art without departing from the spirit and scope of the claims set forth in the following it will be appreciated from the various changes and modifications are possible.
Industrial Applicability
[122]
Formability and surface properties are excellent austenitic stainless steel processed according to embodiments of the present invention is applicable in applications such as sink bowls of kitchen sinks.
[123]

Claims
[Claim 1]
By weight%, C: 0.005 to 0.15%, Si: 0.1 to 1.0%, Mn: 0.1 to 2.0%, Ni: 6.0 to 8.0%, Cr: 16 to 18%, Cu: 0.1 to 4.0%, N: 0.005 to 0.2%, Mo: 0.01 to about a 0.2%, the rest is Fe and unavoidable austenitic comprises a stainless steel, the following equation (1) the surface part piece seats of Ni is defined as containing impurities in the range of 0.6 to 0.9, Maarten a site fraction of 10 to 30% of the surface properties is excellent austenitic stainless steel workpieces. (C Ni -Min ) / (C Ni -Ave ) ... ... Formula (1) where, C Ni -Min is the minimum concentration of Ni in the surface, C Ni -Ave is the average Ni concentration at the surface.
[Claim 2]
According to claim 1, wherein the following formula (2) Surface hardness ratio is 1.1 to 1.6 range of surface properties excellent in austenitic stainless steel of the work piece defined by the. A / B ... ... Equation (2) where, A is the average of the top 10% of the surface hardness of the workpiece, B is the average value of the workpiece surface hardness of the bottom 10%.
[Claim 3]
The method of claim 1, wherein the cracks are less than the depth from the surface 20㎛ 10 or fewer surface properties are excellent austenitic stainless steel workpieces.
[Claim 4]
According to claim 1, Ni surface side seokbu is less than 60% in area fraction, Ni surface part piece seokbu is 5% greater than the surface properties are excellent austenitic stainless steel workpieces by area fraction.
[Claim 5]
By weight%, C: 0.005 to 0.15%, Si: 0.1 to 1.0%, Mn: 0.1 to 2.0%, Ni: 6.0 to 8.0%, Cr: 16 to 18%, Cu: 0.1 to 4.0%, N: 0.005 to 0.2%, Mo: 0.01 to 0.2%, the rest step of processing the austenitic stainless steel which comprises Fe and inevitable impurities; The method comprising annealing the austenitic stainless steel work piece at a temperature of 900 to 1,150 ℃ for 10 minutes or less; And heat treatment of the method of manufacturing austenitic stainless steel excellent in surface properties of the nitro austenitic stainless steel work piece comprising the step of cooling the workpieces within 30 minutes to 500 ℃.
[Claim 6]
The method of claim 5, wherein before heat treatment method for the preparation of the austenitic stainless steel workpieces martensite fraction is 10 to 50% of the surface properties excellent in austenitic stainless steel of the work piece.
[Claim 7]
The method of claim 6, wherein after cooling, the manufacturing method of the austenitic stainless steel workpieces martensite fraction is 10 to 30% of the surface properties excellent in austenitic stainless steel of the work piece.