FIELD OF THE INVENTION:

[0001] The present invention relates to a low silicon ductile iron having silicon in the range of 0.8 to 1.5 weight percentage. More specifically it relates to production of grade 420/10 i.e. a tensile strength of 420 MPa minimum and 10% minimum elongation.
BACKGROUND OF THE INVENTION:
[0002] Ductile iron is produced by magnesium treatment of hot metal received from blast furnace, pig iron melted in cupola or induction furnaces for producing ferritic grades typically carbon is kept between 3.5 % to 4 %, Silicon between 1.8 % to 2 % and Manganese between 0.2 % to 0.7 %. Reference patent number WO2004022791A1, inventor; T Skland. Only the white cast irons which are extremely hard and brittle having poor elongation are produced having low value of silicon (reference US patent number US8328703B2).
[0003] Silicon plays a very important role in the casting behavior and mechanical properties of ductile iron. Fluidity which is a desirable characteristic is directly proportional and formation of carbide or depth of chill, which is undesirable, is inversely proportional with silicon content of the molten metal used for the production of duction iron. Optimum levels of silicon for production of ductile iron grades particularly grey 420/10 or 400/12 were kept between 1.8 to 2.4 weight percent.

[0004] Thin walled ductile iron castings particularly centrifugal castings including ductile iron pipes are produced in metallic moulds there by encountering a very high degree of chill and surface shrinkage. These thin wall casting necessitated an optimum amount of Silicon level 1.8 % to 2.4 %. Thin walled castings always require a heat treatment to achieve a desirable mechanical property. A high carbide percentage occurrence due to low silicon makes heat treatment difficult therefore manufacturers producing thin walled castings use to keep silicon in the said optimum range.
[0005] Production of high silicon hot metal (Silicon 1.8 % to 2.4 %) requires a blast furnace practice with high coke rate or remelting of pig iron, foundry returns and steel scraps with addition of ferro silicon alloy. Both this method results in increased cost and a higher carbon footprint.
[0006] The rare earth metals have long been known to control the chill depth in cast iron also improve nodule count, nodularity and suppression of harmful impact of carbide forming and perlite stabilizing elements. The same was never thought to be a replacement of silicon.
[0007] The chemistries involving higher silicon resulted in higher carbon footprints, environment pollution, resource depletion, employee stress and uncertainty vis a vis silicon addition with varying content of Manganese and tramp elements in the melt or molten metal. The present invention gives a clear mathematical model about production of high elongation ductile iron with the chemistries involved.
OBJECTS OF THE INVENTION:
[0008] An object for the present invention is to propose a low silicon ductile iron composition.

[0009] Another object of this invention is to propose a low silicon ductile iron having silicon in the range of 0.8 to 1.5 wt%.
[0010] Further, object of this invention is to propose low silicon ductile iron wherein silicon is required to provide fluidity to molten iron.
[0011] Still further object of the present invention is to propose low silicon ductile iron wherein the silicon suppresses formation of harmful carbides.
[0012] Yet another object of this invention is to propose low silicon ductile iron wherein the silicon promotes desirable graphite formation.
[0013] Still another object of this invention is to propose low silicon ductile iron to reduce higher carbon footprints, environment pollution, resource depletion, and costs.
BRIEF DESCRIPTION OF THE INVENTION:
[0014] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[0015] The present invention relates to a low silicon ductile iron composition comprising: 3.99 to 4.30% of C; 0.8 to 1.57% of Si; 0.06 to 0.21% of Mn; the balance being represented by iron and inevitable impurities.

[0016] Various objects, features, aspects, and advantages of the inventive subject matter will be more apparent from the following details of preferred embodiments, along with the accompanying drawing figures.
[0017] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects may be combined to form a further embodiment of the disclosure.
[0018] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
[0019] The illustrated embodiments of the subject matter be best understood by reference to the drawings. The following description is intended only by way of example, and simply illustrates certain selected embodiments of method, systems, that are consistent with the subject matter as claimed herein, wherein:
Figure 1: relates to microstructure after annealing un-etched, 100x S1 & S1A.
Figure 2: relates to microstructure after annealing un-etched, 100x S2 & S2A.
Figure 3: relates to microstructure after annealing un-etched, 100x S3 & S3A.

Figure 4: relates to microstructure after annealing un-etched, 100x S4 & S4A.
Figure 5: relates to microstructure after annealing un-etched, 100x S5 & S5A.
Figure 6: relates to microstructure after annealing un-etched, 100x S6 & S6A.
[0020] The figure depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily understand from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The present invention relates to ductile iron having 0.8 % to 1.5 % Silicon, still getting a product that has less than 2% carbide and less than 10 % perlite after heat treatment at a temperature above 910 degree Celsius and achieve a tensile strength of 420 MPa and elongation of 10 % minimum.
[0022] The silicon is kept 0.8 % to 1.5 % and a cerium based misch metal containing 40 % to 60 % Cerium, 20 % to 35 % Lanthanum, balance other rare earths OR Lanthanum OR Cerium is added to hot metal before casting in accordance with the formula given below.
Misch metal addition in gm/ton of hot metal = [{(1.9 + %Mn - %Si) *250 + (Tramp factor – 0.03) *1500}/ (Rare earth correction factor)] …………. FORMULA 1A

or a weight % as in formula given below;
[{0.25*(1.9 + %Mn - %Si) +0.3*(Tramp factor - 0.03)}/ (Rare earth correction factor)]
FORMULA 1B
Where in tramp factor is given by:
Tramp factor = Cu + Mo + V + 2(Co + W + Sb + Bi + Sn + Cr + Pb) + 5 (Te + Se + As +
Sn + B - Ca)
and Rare earth correction factor is given by 0.01316[ %Ce + { (%Nd + %Pr) / 2 } + (%La /
3 )]
[0023] A blast furnace capable of production of various hot metal chemistries between 0.8% to 1.5% Silicon was used for the purpose. The received hot metal was treated with either as received Silicon level or with additional Silicon to match required chemistries. The hot metal received was treated in Georg-Fischer converter with Magnesium level kept between 0.08% to 0.1% to hot metal. The chemistries were prepared to compensate for the silicon by giving the misch metal to bottom of casting ladles in accordance with formula one & two and pipes were cast in centrifugal casting machine with various chemistries in accordance with given formula;
[0024] The pipes of nominal diameter 100-700 mm were cast, and the mechanical test samples were drawn from the spigot end of the pipes. The chemical test samples (coin samples) were taken from the induction furnace before the magnesium treatment and from casting hopper before casting. Pipes thus produced were subjected to an annealing treatment in a chain hearth furnace where holding temperatures were kept 1000 to 1500-degree Celsius (pipe surface temperature 950 to 970 degree Celsius and chain speed 1100 to 1200 mm/min.

[0025] The chemistries and mechanical test results are in table 1 to 7. Also, the micro photographs are given in pictures 1 to 6. The mechanical results very clearly show that Silicon can be compensated by misch metal in accordance with formula one and two over the entire range between 0.8 % and 1.5% Silicon seamlessly. The advantage of the claimed invention is to produce ductile iron with reduced content of Silicon between 0.8 % to 1.5 % weight, which reduces the cost to a great extent. Additionally, the ductile iron of the present invention has higher carbon footprints, resource depletion and environmental pollution too.
[0026] The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a method, LD slag, steel, slurry, filtrate that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such method. In other words, one or more elements in a method proceeded by “comprises…..a” does not, without more constraints, preclude the existence of other elements or additional elements in the method.
Table 1s

MECHANICAL REPORT
DN (mm) TENSILE STRENGTH(MPa) ELONGATION (%) BHN MISCH
METAL
(gm/ton)

150 474 13.84 166 370-380

Table 1y

Melt Condition C Si Mn P S Mg Ti Cr Cu Sn Pb Mo Al Ni
Before
MM
addition 4.4 0.87 0.062 0.139 0.023 <0.005 0.047 0.012 0.0045 0.001 0.0018 0.001 0.001 0.006
After addition 4.25 0.87 0.06 0.147 0.011 0.01 0.05 0.013 0.003 0.0014 0.001 0.001 0.001 0.006

Melt Condition Co Nb V W As Bi Ca Ce Sb B N TF MM
(gm)(with
correction
factor)
Before
MM
addition 0.001 0.001 0.007 0.005 0.004 0.004 0 0.002 0 0 0.01 0.0851 378
After addition 0.001 0.001 0.008 0.005 0.003 0.003 0 0.01 0.001 0 0.01 - -
Table 1

MECHANICAL REPORT
DN (mm) BATCH NO TENSILE STRENGTH(MPa) ELONGATION (%) BHN MISCH
METAL
(gm/ton)

500 1B 491 11.71 164 180-200
450 1A 480 12.51 164 180-200
450 1B 490 12.34 163 180-200
300 1A 480 14.88 166 180-200
300 1B 525 11.52 169 180-200
200 1A 473 13.31 162 180-200

Abbreviations:
DN Nominal diameter
MM Misch Metal
BHN Brinell Hardness Number
TF Tramp Factor

Melt Condition S.No C Si Mn P S Mg Ti Cr Cu Sn Pb Mo Al Ni
Before
MM
addition 1 3.99 1.55 0.144 0.12 8 0.02 7 0.00 5 0.07 8 0.009 0.000 5 0.002 0.001 6 0.001 0 0.000 0.004
After addition 1A 4.01 1.56 0.15 0.12 4 0.00 7 0.02 1 0.07 6 0.009 0.001 0.001 8 0.002 0.001 0 0.0000 0.005
After addition 1B 4.09 1.57 0.15 0.12 3 0.00 8 0.02 3 0.07 6 0.010 0.002 0.001 9 0.002 0.001 0 0.0000 0.005

Co Nb V W As Bi Ca Ce Sb B N TF MM(gm) (with correctio n factor)
Before
MM
addition 1 0.0010 0.007 0.010 0.00 4 0.00 3 0.00 1 0.00 0.002 0.000 0.001 0.008 0.072 6 183
After addition 1A 0.001 0.007 0 0.01 0.00 4 0.00 3 0.00 2 0 0.009 0.000 0.001 0.008 - -
After addition 1B 0.001 0.007 0 0.01 0.00 4 0.00 3 0.00 2 0 0.008 0.000 0.001 0.008 - -
Table 2

MECHANICAL REPORT
DN (mm) BATCH NO TENSILE STRENGTH(MPa) ELONGATION (%) BHN MISCH
METAL
(gm/Ton)
700 2A 443 14.46 157 (180-200)
700 3A 437 12.92 153 (180-200)
700 3B 471 12.97 157 (180-200)
400 2A 534 11.92 170 (180-200)
400 2B 483 11.04 172 (180-200)
400 3A 525 11.44 178 (180-200)
400 3B 489 12.72 167 (180-200)
150 2B 461 15.52 162 (180-200)
150 3A 450 13.68 158 (180-200)
150 3B 472 16.72 164 (180-200)
200 2A 458 11.31 160 (180-200)
200 3A 486 12.97 163 (180-200)
200 3B 460 13.37 160 (180-200)
100 2A 488 14.46 166 (180-200)
100 2B 437 13.26 152 (180-200)
100 3A 456 17.44 158 (180-200)
100 3B 447 12.96 160 (180-200)

Table 2A

Melt Condition S.No C Si Mn P S Mg Ti Cr Cu Sn Pb Mo Al Ni
Before
MM
addition 2 4.05 1.47 0.074 0.112 0.019 <0.005 0.071 0.008 0.0014 0.002 0.0021 0.001 0.001 0.004
Before
MM
addition 3 3.99 1.45 0.075 0.114 0.017 <0.005 0.069 0.008 0.0007 0.002 0.0018 0.001 0.001 0.004
After addition 2A 4.08 1.49 0.08 0.104 0.006 0.022 0.069 0.008 0.002 0.0017 0.002 0.001 0.001 0.004
After addition 2B 4.03 1.44 0.07 0.116 0.007 0.020 0.068 0.009 0.002 0.0018 0.002 0.001 0.001 0.004
After addition 3A 4.00 1.43 0.07 0.116 0.005 0.016 0.067 0.009 0.003 0.0019 0.002 0.001 0.001 0.004
After addition 3B 4.04 1.45 0.07 0.118 0.009 0.022 0.067 0.008 0.002 0.0018 0.002 0.001 0.001 0.004

Co Nb V W As Bi Ca Ce Sb B N TF MM(gm)(with
correction
factor)
Before
MM
addition 2 0.0010 0.007 0.01 0.003 0.004 0.003 0.001 0.002 0.001 0.00 0.01 0.0753 188
Before
MM
addition 3 0.0000 0.007 0.009 0.003 0.003 0.002 0.001 0.002 0.001 0.00 0.00 0.0641 177
After addition 2A 0.001 0.0070 0.009 0.003 0.003 0.002 0.001 0.009 0.001 0 0.01 - -
After addition 2B 0.001 0.0070 0.009 0.003 0.003 0.003 0.001 0.009 0.001 0 0.01 - -
After addition 3A 0.001 0.0070 0.009 0.003 0.003 0.004 0.001 0.01 0.001 0 0.01 - -
After addition 3B 0.001 0.0070 0.009 0.003 0.004 0.002 0.001 0.01 0.001 0 0.01 - -
Table 3

MECHANICAL REPORT
DN (mm) BATCH NO TENSILE STRENGTH(MPa) ELONGATION (%) BHN MISCH
METAL
(gm/ton)
600 4A 424 17.44 150 250-260
600 4A 438 15.04 155 250-260
600 4B 426 18.6 150 250-260
600 4B 448 12.64 154 250-260
500 4A 435 16.46 154 250-260
500 4B 420 16.57 150 250-260
500 4B 451 13.37 152 250-260
150 4A 458 18.64 150 250-260
150 4B 440 15.44 158 250-260
200 4A 462 18.4 154 250-260
200 4B 464 15.44 160 250-260
100 4A 473 14.16 157 250-260
100 4B 452 16.69 156 250-260

Table 3A

Melt Condition S.No C Si Mn P S Mg Ti Cr Cu Sn Pb Mo Al Ni
Before
MM
addition 4 4.23 1.35 0.107 0.115 0.019 <0.005 0.055 0.014 0.0036 0.002 0.0021 0.0010 0.002 0.006
After addition 4A 4.08 1.37 0.11 0.103 0.008 0.020 0.054 0.014 0.005 0.0018 0.002 0.0010 0.0020 0.006
After addition 4B 4.11 1.37 0.11 0.112 0.009 0.024 0.055 0.014 0.004 0.0018 0.002 0.0010 0.0020 0.006

Co Nb V W As Bi Ca Ce Sb B N TF MM(gm)(with
correction
factor)
Before
MM
addition 4 0.0010 0.001 0.008 0.005 0.003 0.003 0 0.002 0 0.00 0.01 0.0877 248
After addition 4A 0.002 0.0010 0.008 0.005 0.003 0.004 0.00 0.011 0.00 0 0.01 - -
After addition 4B 0.001 0.0010 0.008 0.005 0.003 0.004 0.00 0.011 0.00 0 0.01 - -
Table 4

MECHANICAL REPORT
DN (mm) BATCH NO TENSILE STRENGTH(MPa) ELONGATION (%) BHN MISCH
METAL
(gm/ton)

600 5A 427 14.11 148 250-260
600 5B 457 11.2 152 250-260
500 5A 444 16.91 153 250-260
500 5B 437 15.89 152 250-260
150 5A 446 14.85 153 250-260
150 5B 429 14.48 152 250-260
100 5A 449 16.8 154 250-260
100 5B 448 11.84 154 250-260

Table 4A

Melt Condition S.No. C Si Mn P S Mg Ti Cr Cu Sn Pb Mo Al Ni
Before
MM
addition 5 4.14 1.21 0.102 0.118 0.018 <0.005 0.068 0.014 0.0029 0.002 0.0013 0.0010 0.002 0.006
After addition 5A 4.09 1.32 0.10 0.121 0.007 0.021 0.064 0.014 0.004 0.0018 0.002 0.0010 0.0020 0.006
After addition 5B 4.10 1.27 0.10 0.120 0.009 0.020 0.065 0.014 0.004 0.0018 0.002 0.0010 0.0020 0.006

Co Nb V W As Bi Ca Ce Sb B N TF MM (gm)(with correction factor)
Before
MM
addition 5 0.0010 0.001 0.008 0.004 0.003 0.002 0.001 0.001 0.001 0.00 0.01 0.0782 257
After addition 5A 0.001 0.0010 0.008 0.005 0.003 0.003 0.001 0.01 0.001 0 0.01 - -
After addition 5B 0.001 0.0000 0.008 0.005 0.004 0.003 0.001 0.009 0.001 0 0.01 - -
Table 5

MECHANICAL REPORT
DN (mm) BATCH NO TENSILE STRENGTH(MPa) ELONGATION (%) BHN MISCH
METAL
(gm/ton)
600 6A 430 13.02 151 280-290
600 7A 465 11.2 145 280-290
350 6A 441 13.6 156 280-290
250 7A 437 14.85 151 280-290
250 7B 461 13.68 156 280-290
150 6A 457 15.12 148 280-290
150 7A 438 14.8 148 280-290
150 7B 438 14.4 151 280-290
100 7B 434 11.92 151 280-290

Table 5A

Melt Condition S. No. C Si Mn P S Mg Ti Cr Cu Sn Pb Mo Al Ni
Before MM addition 6 4.18 1.03 0.06 0.126 0.019 <0.005 0.062 0.015 0.003 0.0016 0.001 0.0010 0.0030 0.0070
Before MM addition 7 4.30 1.03 0.06 0.122 0.020 <0.005 0.060 0.016 0.004 0.0017 0.001 0.0010 0.0030 0.0070
After addition 6A 4.23 1.01 0.06 0.124 0.008 0.019 0.062 0.016 0.004 0.0017 0.001 0.0010 0.0010 0.007
After addition 7A 4.12 1.02 0.06 0.129 0.007 0.018 0.059 0.015 0.004 0.0016 0.001 0.0010 0.0020 0.007
After addition 7B 4.21 1.01 0.06 0.132 0.009 0.025 0.057 0.016 0.004 0.0017 0.001 0.0010 0.0020 0.007

Co Nb V W As Bi Ca Ce Sb B N TF MM(gm)(with correction factor)
Before MM addition 6 0.001 0.0010 0.009 0.004 0.003 0.002 0 0.001 0 0.0001 0.00 0.0827 282
Before MM addition 7 0.001 0.0010 0.009 0.004 0.003 0.002 0 0.001 0 0.0002 0.00 0.0874 288
After addition 6A 0.001 0.0010 0.008 0.004 0.003 0.001 0 0.01 0 0 0.00 - -
After addition 7A 0.002 0.0010 0.009 0.004 0.003 0.002 0 0.011 0 0 0.00 - -
After addition 7B 0.001 0.0010 0.008 0.004 0.003 0.002 0 0.012 0 0 0.00 - -
Table 6

MECHANICAL REPORT
DN (mm) BATCH NO TENSILE STRENGTH(MPa) ELONGATION (%) BHN MISCH
METAL
(gm/ton)
750 8A 444 13.48 150 (270-280)
750 9A 434 13.00 148 (300-310)
750 9B 425 14.16 148 (300-310)
500 8A 431 16.57 149 (270-280)
500 9A 431 17.48 148 (300-310)
500 9B 448 17.82 152 (300-310)
300 8A 445 16.96 152 (270-280)
300 9A 438 16.08 149 (300-310)
300 9B 466 15.68 154 (300-310)

Table 6A

Melt Condition S.No. C Si Mn P S Mg Ti Cr Cu Sn Pb Mo Al Ni
Before
MM
addition 8 4.18 1.03 0.06 0.126 0.019 <0.005 0.062 0.015 0.003 0.0016 0.001 0.0010 0.0030 0.0070
Before
MM
addition 9 4.30 1.03 0.06 0.122 0.020 <0.005 0.060 0.016 0.004 0.0017 0.001 0.0010 0.0030 0.0070
After addition 8A 4.23 1.01 0.06 0.124 0.008 0.019 0.062 0.016 0.004 0.0017 0.001 0.0010 0.0010 0.007
After addition 9A 4.12 1.02 0.06 0.129 0.007 0.018 0.059 0.015 0.004 0.0016 0.001 0.0010 0.0020 0.007
After addition 9B 4.21 1.01 0.06 0.132 0.009 0.025 0.057 0.016 0.004 0.0017 0.001 0.0010 0.0020 0.007

Co Nb V W As Bi Ca Ce Sb B N TF MM(gm)(with
correction
factor)
Before
MM
addition 8 0.001 0.0010 0.009 0.004 0.003 0.002 0 0.001 0 0.0001 0.00 0.0827 282
Before
MM
addition 9 0.001 0.0010 0.009 0.004 0.003 0.002 0 0.001 0 0.0002 0.00 0.0874 288
After addition 8A 0.001 0.0010 0.008 0.004 0.003 0.001 0 0.01 0 0 0.00 - -
After addition 9A 0.002 0.0010 0.009 0.004 0.003 0.002 0 0.011 0 0 0.00 - -
After addition 9B 0.001 0.0010 0.008 0.004 0.003 0.002 0 0.012 0 0 0.00 - -
Table 7
Analysis of microstructures and photographs

Table No. Photograph No. N COUNT NODULARITY PEARLITE CARBIDE
1 S1, S1A 1006 81.96 9 0
2 S2, S2A 1025 79.9 7 0
3 S3, S3A 749 80.86 10 0
4 S4, S4A 749 80.86 5 0
5 S5, S5A 614 84.72 5 0
6 S6,S6A 987 76.72 7 0
[0027] It is to be noted that a person skilled in the art would be motivated from the present disclosure to arrive at a methodology for production of different value added products and different novel composites. Such method may vary based on configuration of one or more

ingredients. However, such modifications should be construed within the scope of the disclosure. Accordingly, the drawings illustrate only those specific details that are pertinent to understand the embodiments of the present disclosure, so as not to obscure the disclosure with details that will be clear to those of ordinary skill in the art having benefit of the description herein.
As used in the description herein and throughout the claims that follow, the meaning of “a”, “an”, and “the” includes plural reference unless the context clearly dictates otherwise.
[0028] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0029] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

Equivalents:
[0030] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
[0031] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to”, the term “having” should be interpreted as “having at least”, the term “includes” should be interpreted as “includes but is not limited to”, etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, eve it a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the

bare recitation of “two recitations”, without other modifiers, typically means at least two recitations, or two or more recitations).
[0032] The above description does not provide specific details of the method of the various parameters. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.
[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other methods or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0034] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0035] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and

embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

WE CLAIM:
1. A low silicon ductile iron composition comprising:
3.99 to 4.30% of C; 0.8 to 1.57% of Si; 0.06 to 0.21% of Mn; the balance being represented by iron and inevitable impurities.
2. The composition as claimed in claim 1, wherein silicon is kept between 0.8 to 1.5%
and a cerium based misch metal is added before casting to the hot metal in gm/ton in
accordance to the formula:
[{(1.9 + %Mn - %Si) * 250 + (Tramp fractor – 0.03) * 1500} / (Rare earth correction
factor)]….. Formula 1A
or in weight % as in formula
[{0.25*(1.9 + %Mn - %Si) +0.3*(Tramp factor – 0.03)}/ (Rare earth correction
factor)] ……Formula 1B.
3. The composition as claimed in claim 1, wherein the Tramp factor is given by the
formula Cu + Mo + V + 2(Co + W + Sb + Bi + Sn + Cr + Pb) + 5 (Te + Se + As +
Sn + B – Ca)……………Formula 2
and Rare earth correction factor is given by by 0.01316[ %Ce + { (%Nd + %Pr) / 2} + (%La / 3 )] ……………………..Formula 3

4. The composition as claimed in claim 1, wherein the amount of silicon can be compensated by misch metal in accordance to formula 1A / 1B.
5. The composition as claimed in claim 1, wherein the silicon content has been reduced to a range of 0.8 to 1.5 weight%.