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Cast austenitic stainless steel

a technology cast steel, which is applied in the field of austenitic stainless steel, can solve the problems of poor aging ductility and embrittlement of steel casting, and achieve the effects of reducing weld cracking, improving productivity, and enhancing fluidity

Inactive Publication Date: 2014-02-27
KUBOTA LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention is a new type of austenitic stainless cast steel with excellent properties such as aging ductility, tensile strength, and oxidation resistance. This new steel can be produced by cooling from a high temperature range to a low temperature range at a fast cooling rate. By doing so, the new steel has excellent strength without the need for a solution heat treatment.

Problems solved by technology

This may lead to embrittlement of the steel casting.
When CF8C is exposed to high temperature for a long period of time under usage environment, the sigma phase is precipitated to cause aging embrittlement, and thus aging ductility may become poor.

Method used

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  • Cast austenitic stainless steel

Examples

Experimental program
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Effect test

example 1

[0045]Example of the present invention will be described. The main components (percent by mass) of the austenitic stainless cast steel of the present invention (Examples 1-1-1-6) and CF8C (Comparative Examples 1-1-1-5) are shown in Tables 2 and 3, respectively.

TABLE 2Example1-11-21-31-41-51-6Ferrite (volume0.20.20.20.20.20.2fraction (%))C0.040.030.040.030.080.06(percent by mass)Si0.760.860.760.860.890.86(percent by mass)Mn2.072.152.072.152.072.12(percent by mass)Cr20.5519.9020.5519.9022.3522.10(percent by mass)Ni11.3811.1211.3811.1210.5010.34(percent by mass)Nb0.270.260.270.260.290.32(percent by mass)N0.210.200.210.200.190.21(percent by mass)

TABLE 3Comparative Example1-11-21-31-41-5Ferrite (volume fraction (%))12.09.0000C (percent by mass)0.030.030.0170.080.06Si (percent by mass)0.470.630.370.480.57Mn (percent by mass)1.044.481.831.022.02Cr (percent by mass)19.9819.9319.9319.3519.60Ni (percent by mass)9.929.4511.6311.4911.55Nb (percent by mass)0.590.420.430.690.71N (percent by mass)...

example 2

[0054]In Example 1, the volume fraction of the ferrite phase of the austenitic stainless cast steel of the present invention was 0.2% (Examples 1-1-1-6). In addition, also for a case in which the volume fraction of the ferrite phase is 1-3%, aging ductility, tensile strength, 0.2% proof stress and oxidation resistance were examined (Examples 2-1-2-4) under the same condition for Example 1. The components of Examples 2-1-2-4 are shown in Table 5, and the results are shown in Table 6.

TABLE 5Example2-12-22-32-4Ferrite (volume fraction (%))2131C (percent by mass)0.0140.0130.0200.013Si (percent by mass)0.670.720.620.72Mn (percent by mass)2.262.372.002.22Cr (percent by mass)21.1021.1021.7022.22Ni (percent by mass)11.2911.3812.0911.54Nb (percent by mass)0.290.290.270.27N (percent by mass)0.220.230.160.23

TABLE 6AgingTensile0.2% proofOxidationductilitystrengthstressresistance(%)(Mpa)(Mpa)(mm / year)Example 2-127.0128890.006Example 2-224.0123880.058Example 2-327.095630.558Example 2-420.4137880....

example 3

[0056]With respect to the austenitic stainless cast steel whose Mn content was approximately 1.0-4.5 percent by mass, oxidation resistance (mm / year) was examined. As the austenitic stainless cast steel of the present invention, those with the Mn content of 2.26 percent by mass (Example 3-1) and 2.33 percent by mass (Example 3-2) were used. As the austenitic stainless cast steel of Comparative Example, those with the Mn content of 1.04 percent by mass (Comparative Example 3-1), 1.17 percent by mass (Comparative Example 3-2), 1.81 percent by mass (Comparative Example 3-3), 4.37 percent by mass (Comparative Example 3-4), and 4.48 percent by mass (Comparative Example 3-5) were used. The components for these Examples and Comparative Examples are shown in Table 7. The results are shown in Table 8 and FIG. 1.

TABLE 7ExampleComparative Example3-13-23-13-23-33-43-5Ferrite (volume231280.2109fraction (%))C (percent by mass)0.030.030.030.030.0170.030.03Si (percent by mass)0.650.640.470.610.360.6...

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Abstract

An austenitic stainless cast steel having a volume fraction of a ferrite phase of 0.1-5.0%.

Description

TECHNICAL FIELD[0001]The present invention relates to an austenitic stainless cast steel.BACKGROUND ART[0002]An austenitic stainless cast steel exhibits excellent properties especially in corrosion resistance, strength, weldability and the like, and has been widely used for piping, valves and the like in chemical plants and power plants. The austenitic stainless cast steel is formed of, for example from metallurgical viewpoint, two phases including approximately 10-20% of an alpha phase and approximately 90-80% of a gamma phase (austenitic phase).[0003]As for steel castings of the austenitic stainless steel, CF8C has been known. For example, a CF8C austenitic stainless steel casting includes: up to 0.08 percent by mass of C (carbon); up to 2.0 percent by mass of Si (silicon); up to 1.5 percent by mass of Mn (manganese); 18.0-21.0 percent by mass of Cr (chromium); 9.0-12.0 percent by mass of Ni (nickel); and up to 1.0 percent by mass of Nb (niobium).[0004]CF8C includes approximately ...

Claims

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Application Information

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IPC IPC(8): C22C38/58C22C38/00C22C38/02C22C38/48
CPCC22C38/58C22C38/02C22C38/001C22C38/48C21D6/004C21D2211/001C21D2211/005C21D6/02B22D27/20B22D30/00C22C38/004C22C38/40
Inventor SAKAMOTO, NOBUYUKIHINENO, MAKOTO
Owner KUBOTA LTD