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Publication numberUS3716354 A
Publication typeGrant
Publication dateFeb 13, 1973
Filing dateNov 2, 1970
Priority dateNov 2, 1970
Publication numberUS 3716354 A, US 3716354A, US-A-3716354, US3716354 A, US3716354A
InventorsReen O
Original AssigneeAllegheny Ludlum Ind Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
High alloy steel
US 3716354 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

United States atent 3,716,354 HIGH ALLUY STEEL Orville W. Reen, Lower Burrell, Pa, assignor to Allegheny Ludlum Industries, Inc, Pittsburgh, Pa. No Drawing. Filed Nov. 2, 1970, Ser. No. 86,358 Int. Cl. CZZc 39/20, 39/50 US. Cl. 75128 W Claims ABSTRACT OF THE DISCLOSURE Described herein is a composition consisting essentially of, in weight percent, 16-25% chromium, -22% nickel, 4-l0% molybdenum, up to 0.08% carbon, up to 2.0% manganese, up to 1.5% silicon and the balance essentially iron and steel making residuals.

Stainless steel has been frequently used in applications requiring resistance to corrosion in environments involving exposure to chloride and chlorine ions. Commonly used materials for these applications have been high alloy stainless steels such as type 316 and type 3161.. Such high alloyed compositions, however, suffer from the disadvantage that they are difficult to hot work and as a result pose serious fabrication problems.

In some cases it has been suggested to utilize powder metallurgical techniques to produce articles of high alloy stainless steel to avoid the aforementioned fabrication difficulties which may be associated with such materials.

However, because of their porous nature, pressed and sintered stainless steel powder articles are particularly subject to corrosive attack as a result of susceptibility to crevice corrosion. Even such high alloyed materials as type 316 and type 316L prove inadequate in pressed and sintered articles when exposed to corrosion testing. This is evidenced by the failure of sintered parts of type 316L to withstand 100 hours exposure in 5% neutral sodium chloride spray without rusting. This rusting has been found to occur at all levels of density up to, but not including, 100% and is attributed to the presence of pores in the surface. It is evident that there is a need for stainless steel compositions which, when manufactured into articles from powder metal, will provide more resistance to corrosive environments such as the chlorine ion than that of type 316L steels and possess improved resistance to crevice corrosion as a pressed and sintered article.

The present invention provides a novel composition which avoids the aforementioned difiiculties associated with powder metal parts manufactured of presently available high alloy steel powders. In accordance with the invention there is provided a composition consisting essentially of, in weight percent, up to 0.08% carbon, preferably up to 0.03%; up to 2.0% manganese, preferably up to0.3%; up to 1.5% silicon, preferably 0.6 to 1.25%; 16 to 25% chromium, preferably 17 to 25%; 10 to 22% nickel, preferably 14 to 22%; 4 to 10% molybdenum, preferably 47%; and the balance essentially iron and the usual steel making residuals. Alloys, in accordance with the invention, may be melted and atomized into pre-alloyed powder and then pressed and sintered into powder metal components of greater corrosion resistance than possessed by the most highly alloyed commercially available stainless steel powder, e.g., type 316L. The minimum values of the alloying elements chromium, nickel and molybdenum, in the foregoing broad range have been found to be the minimum amounts necessary to obtain satisfactory corrosion resistance for these alloys in powder articles. However, no significant improvement is observed beyond the maximum values. For commercial powder metallurgical operations, it is desirable to utilize irregularly shaped particles. The preferred limits of 0.3% maximum manganese and at least 0.6% silicon are established to maximize the desirable particle configuration.

The following examples illustrate the practice of the invention and the superior properties obtainable thereby.

Atomized powders of the compositions described in Table I were prepared and screened to a size suitable for powder metal processing (about 0.149 mm. and finer), having the characteristics described in Table II. Thereafter they were pressed into compacts and sintered in dry hydrogen at temperatures of 2000 to 2200 F. The sintered compacts were about to of their full density. A commercial type 316L powder was pressed and sintered in a similar fashion.

TABLE I P S S1 Cr Ni Mo Fe O. 008 0. 005 1. 05 17. 97 10. 22 4. 92 Balanc 1.014 0.008 0.80 16.85 12.78 2.34 Do. 0.010 0.004 0.95 18.05 12.20 4.80 Do. 0. 003 0.003 0.81 17.65 15.05 3.07 Do. 0.008 0.006 0.79 17.69 14. 05 4.02 Do. 0.012 0.004 0.86 17. 74 15.00 5.05 D0. 0.008 0.003 0.90 17. 92 14. 90 7.05 D0. 0.013 0.003 0.84 17.75 19.86 6.96 D0. 0.010 0.011 0.74 21. 16 12. 08 4.00 Do. 0. 015 0.008 0.76 21.40 12.80 5.00 Do. 0.015 0.007 0.70 20.88 21.60 7.30 Do. 0.018 0.013 0.71 24.08 20.88 4.00 D0.

TABLE II Properties of Atomized Pre-Alloyed Powders Mesh size distribution, wt. percent Flow, Apparent seeonds/ density, Run No 100/+200 200/+325 325 50g gJcu. cm

1 ASTM Method 13213-48. 2 ASTM Method 13212-48.

The pressed and sintered compacts of the compositions disclosed in Table I were exposed to the following corrosive environments:

(1) neutral NaCl spray (2) Immersion in aqueous solutions of 5, 10, and 20 weight percent NaCl.

(3) Immersion in aqueous solutions of 5, and

weight percent NI-I Cl.

of atmospheres may be used. In addition the density of the compacts produced may vary depending upon the nature of the article manufactured.

I claim:

1. An atomized, prealloyed powder consisting essentially of, in weight percent, up to 0.08% carbon, up to 0.3% manganese, 0.6 to 1.25% silicon, 16 to chromium, 10 to 22% nickel, 4 to 10% molybdenum and the balance essentially iron and steel making residuals.

2. An atomized, prealloyed powder according to claim 1 having 4 to 7% molybdenum.

3. An atomized, prealloyed powder according to claim 1 having 17 to 25% chromium.

4. An atomized, prealloyed powder according to claim 1 having 14 to 22% nickel.

5. An atomized, prealloyed powder according to claim 1 having up to 0.03% carbon, 17 to 25% chromium, 14 to 22% nickel and 4 to 7% molybdenum.

TABLE III Corrosion Test; Results of Pressed and Sintered Atomized Pre-Alloyed Powders 100 hour Qast. Smtered Percent exposure to Hours to rust when immersed in aqueous solutions ofdensity, density, of east 5% neutral Run No. gJcu. em. g Icu. cm. density salt spray 1 5% N 9.01 10% NaCl 20% N 2.01 5% NH4C1 10% NHlCl 20% NHrCl 416 7. 88 5. 95 75. 5 504 N.R 168 504 N.R. 504 N.R. 48. Commercial T316". 2 7. 90 6. 28 79. 5 24 3 504 N.R 24 3. 418 7. 97 5. 6G 71. 0 168 24 504 N.R 504 N.R. 24. 7. 97 5. S3 73. 2 528 N.R. 96 504 N.R 504 N.R. 06. 7.98 5. 85 73. 3 528 N.R. 600 N.R. 504 N.R 528 N.R 7. 99 6. 02 75. 3 504 N.R. 168 504 N.F 504 N.R 24. 8. 01 5. 61 70.0 528 N.R. 600 N.R. 504 N.R 528 N.R 528 N.R 8.02 5. 67 70.7 528 N.R. 600 N.R. 504 N.R 504N.R 504N.R 7. 91 5. 68 71. 8 504 N.R. 24 504 N.R 504 N.R 24. 7. 86 5. 54 70.5 504 N.R. 168 504 N.R 504 N.R 24. 8. 04 5. 69. 7 528 N.R. 600 N.R 504 N.R 504 N.R 504 N.R 7.81 5.50 70.4 528 N.R. 600 N.R 504 N.R 504N.R 504 N.R 7.93 5.44 68.6 504 N.R. 600 N.R 504 NJ?! 504 N.R 504 N.R

l ASTM Method B117. 9 Published value.

NOTE.-N.R.=NO rust.

References Cited UNITED STATES PATENTS 2,819,161 1/1958 Cupler 126 3,547,625 12/ 1970 Bieber, et al. 75-128 2,872,311 2/ 1959 Marshall 75200 3,334,999 8/ 1967 Naeser 75-200 X 3,425,813 2/ 1969 Orlemann 75--0.5 BA X 3,520,680 7/ 1970 Orlemann 75-200 X OTHER REFERENCES Metals Handbook, 8th Edition, Vol. 1, Properties and Selection of Metals, American Society for Metals, Metals Park, Ohio, pp. 408 and 409.

L. DEWAYNE RUTLEDGE, Primary Examiner I. LEGRU, Assistant Examiner US. Cl. X.R.

750.5 BA, 0.5 C

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3899319 *Oct 29, 1974Aug 12, 1975Hoeganaes AbPowder mixture for the production of alloy steel with a low content of oxide inclusions
US4028094 *Oct 29, 1975Jun 7, 1977Allegheny Ludlum Industries, Inc.Stainless steel powder
US4078920 *Jan 28, 1977Mar 14, 1978Avesta Jernverks AktiebolagAustenitic stainless steel with high molybdenum content
US4161241 *Dec 12, 1977Jul 17, 1979Colt Industries Operating Corp.Dashpot apparatus including a flexible diaphragm piston
US4166736 *Jun 14, 1978Sep 4, 1979Metallurgical International, Inc.Powdered metal filter composition and processes for producing the same
US4287068 *Sep 4, 1979Sep 1, 1981Metallurgical International, Inc.Powdered metal filter composition and processes for producing the same
US4310354 *Jan 10, 1980Jan 12, 1982Special Metals CorporationProcess for producing a shape memory effect alloy having a desired transition temperature
US4530720 *Nov 21, 1983Jul 23, 1985Sumitomo Metal Industries, Ltd.High temperature oxidation resistant austenitic steel
US4911886 *Mar 17, 1988Mar 27, 1990Allegheny Ludlum CorporationAustentitic stainless steel
US5393487 *Aug 17, 1993Feb 28, 1995J & L Specialty Products CorporationSteel alloy having improved creep strength
EP0016225A1 *May 8, 1979Oct 1, 1980Sumitomo Metal Industries, Ltd.Use of an austenitic steel in oxidizing conditions at high temperature
Classifications
U.S. Classification420/52, 420/586.1, 75/246
International ClassificationC22C38/44
Cooperative ClassificationC22C38/44
European ClassificationC22C38/44
Legal Events
DateCodeEventDescription
Jan 3, 1989ASAssignment
Owner name: PITTSBURGH NATIONAL BANK
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. RECORDED ON REEL 4855 FRAME 0400;ASSIGNOR:PITTSBURGH NATIONAL BANK;REEL/FRAME:005018/0050
Effective date: 19881129
Mar 24, 1987ASAssignment
Owner name: PITTSBURGH NATIONAL BANK
Free format text: SECURITY INTEREST;ASSIGNOR:ALLEGHENY LUDLUM CORPORATION;REEL/FRAME:004855/0400
Effective date: 19861226
Dec 29, 1986ASAssignment
Owner name: ALLEGHENY LUDLUM CORPORATION
Free format text: CHANGE OF NAME;ASSIGNOR:ALLEGHENY LUDLUM STEEL CORPORATION;REEL/FRAME:004779/0642
Effective date: 19860805