US2227891A - Ferrous alloy - Google Patents

Description

Patented Jan. 7, 1941 UNITED STATES PATENT OFFICE 2,227,891 FERROUS ALLOY Robert S. Rose, Waban, Masa, assignor to Vanadium-Alloys Steel Company, Latrobe, Pa., a corporation of Pennsylvania No Drawing. Application February 29, 1940, Serial No. 321,524

2 Claims. (01. 75-128) This invention relates to ferrous alloys, and been hardened in oil from 1800 degrees F. and more particularly to an improved alloy having tempered to 1000 degrees F., are as follows:

heat and corrosion resisting properties.

There are many uses to which alloy composi- Temperature Brinell s tions are put that call for a high capacity to 5 resist heat and corrosion, and although numer- Room temperature... 277 ous compositions of this general type are avail- $333222? 2g; able at present, they fail in several respects to 400 degrees F1 I' 248 embody the important characteristics of the gggggggg 3? present composition. Thus, a typical alloy which 700 degrees FIZZ 235 10 is in use at the present time is of the following figgggggg 5: ggg approximate chemical composition: 1000 degrees F m 1100 degrees F 159 PB! cent 1200 degrees F 129 Carbon .12

Silicon 30 This is virtually a ferritic alloy, resulting from 15 Manganese the potency of tungsten so stabilizing the alpha- Chromium 12-00 phase as to prevent any significant thermal with the balance iron, except for impurities. d il y- This material, although widely used today, falls Pursuing the foregoing line of investigation, a 20 substantially short of embodying the same d composition has now been discovered which, as gree of heat resistance at high temperature that stated above, emb d s heat resisting q fies does the alloy of the present inv ti By substantially above those already recited. This quenching the above alloy in oil from 1725 decomposition falls within the following average 5 grees F., results in a hardness of 375 Brinell, chemistry range: Per cent and on tempering to 1050, will have a hardne s carbon of .330 Brinell. If tested in this C nd ti n, t Tungsten 490 Brinell hardness of various elevated temperatures Chromium 10304790 are as Nickel .75 2.15 Temperature 'Bflnen with the balance of the alloy substantially iron, 30

except for such customary additive elements as 330 silicon, manganese and the like. 2% It has been found that this material has physi- 310 cal properties radically difierent than would be 33% indicated by the mere difference of composition. 280 The nickel present crystallizes with a face cenggg tered cubic lattice as does gamma iron (austen- 225 ite) and thus stabilizes this phase. Added in sufigg ficlent quantity to the ferritic tungsten-chromium alloy, it extends the gamma loop, permitn 1n order to increase the hardness of the alloy P 2533 :%ggg i g fi gfgs g53 22325 2 1; at elevated temperatures, particularly the hot softening rate at high temperature and mcreas hardness and attendant tensile and yield strength, mg the elevated temperature hardness, are

the foregoing alloy can be modified as follows: cured in a hardenable alloy. 45

Per cent A specific composition falling within the gen- Carbon nu .10 eral range set forth above may be recited as a gggggnese preferred example. Per cent Chr mium 13-00 51m, 3 ,1; Tungsten Manganese .60

Hot Brinell hardnesses taken at the same 100 Tungsten 3.00 degree intervals from room temperature to 1200 Chromium 13.00

65 degrees F., on pieces of this material which have Nickel 1.75

ness tests on the material quenched from two different temperatures are-as follows:

1725 degrees F. quenched in air, tempered at 1000 degrees F.

Temperature Brinell Room temperature 401 200 c egress F 401 800 degrees F 388 fi wi iii r M I 375 100 1 egress F 375 800 F 888 000 1 egrees F 363 1000 degrees F 321 1100 degrees F 187. 1210 degrees F 103 1800 degrees F. quenched in oil, tempered at 1000 degrees F.

Temperature Brincli Room temperature 418 no degrees F 418 sec degrees F 402 400 degrees I 402 500 degrees F 402 000 degrees F 402 700 degrees 1" 402 M degrees I 402 in degrees I 402 388"; it;

(m 1200 c egress I 100 In addition to the greatly improved hot hardness, tensile strength and yield strength at high temperatures, the room temperature physical properties, after quenching in air from 1725 de- Prod Tam, Percent Percent Y elongareduction Brinell stress strength on o! m 81.400 136.600 ias sees no Stainless iron. the currently used material, has the iollowing properties after the same treatment:

Tensile Percent Percent elongareduction Brlnell smut! tion of area It may be stated from one standpoint that the instant invention relates primarily to the introduction of a combination of nickel and tungsten as necessary ingredients into an alloy steel having a chromium content-lying within the stainless range. The introduction oi nickel and tungsten in the manner described herein results in the production of a steel that remains stable at high temperatures. Heretoiore it has been suggested that molybdenum be employed with or without nickel for this purpose, but I have discovered that molybdenum has a tendency to oxidize from the steel surface when the steel is heated to elevated temperatures, and Theme discovered further that this is not true of tungsten. Accordingly, ii. the steel is to be employed at high temperatures the stability oi tungsten is such that in many instances it cannot be replaced by molybdenum.

Having thus described my invention, I claim an alloy steel adapted to be employed at elevated temperatures, said steel being oi the following general composition:

1. A heat and corrosion resisting ferrous alloy, containing mm .0596 to .25% carbon, from 10.00% to 17.00% chromium, from 1.00% to 4.00% tungsten, from .75% to 2.75% nickel, a silicon content 01' less than 1.5%, and a manganese content of less than 1.5%, with the remainder of the alloy all'lron.

2. A heat resisting ferrous alloy, containing approximately .12% carbon, approximately 13.00% chromi approximately 1.75% nickel, approximately 8.00% tungsten, approximately 30% silicon, and approximately .60% manganese, with the remainder oi the alloy all iron.

ROBERT S. ROSE.