US2174285A - Ferrous alloy - Google Patents

Description

Patented Sept. 26, 1939 2,174,285

UNITED STATES PATENT OFFlCE.

FERROUS ALLOY James P. Gill, Introbe, Pa., assignor to Vanadium-Alloys Steel Company, Latrobe, Pa., a corporation of Pennsylvania No Drawing. Original application February 21,

1939, Serial No. 257,686. Divided and this application March 30, 1939, Serial No. 264,986

1 Claim. (Ci. 75-126) This invention relates to alloy steels and more bon or more have not heretofore been regarded particularly to alloy steels which are especially as commercially iorgeable, and an important suitable for use in the manufacture of tools or feature of the present invention resides in the dies, and the present application is a division of discovery, and the attendant disclosure, that such my co-pending application Serial No. 257,686, steels may be rendered readily forgeable by in- 5 filed February 21, 1939. corporating in them approximately three times At present there are a number oi steels oi as much vanadium as carbon present. Steels this nature in use but as a rule, in order to make so prepared have extremely high resistance to them conform to the general requirements of wear, can be hardened extremely hard, some of ready iorgeability and machinability, they are not them even as high as Rockwell C '70, yet they can 1 sufficiently hard to offer a high resistance to be annealed to a hardness of under 275 Brinell, abrasion. With this in mind, an important object at which hardness they are commercially maof the present invention resides in the provision chinable. of an improved alloy steel of this character which In establishing the premises of my invention can be hardened to a Rockwell hardness in 83- several series of heats of steel were prepared, cess of C 60, whereby it offers a high resistance some 01 which will be described in the ensuing to abrasion, and yet can be readily forged and paragraphs. annealed so as to be commercially machinable. Heat No. 1

A feature of the invention which contributes to the accomplishment of the recited object cong g rgf gg; g zg gg g -:32 sists in the discovery that by the employment of ater i dium in .a predetermined ratio in steels of v w c y quenc g w 0 Vans 1750 F., produced a hardness of Rockwell C 69, the type under discussion it is possible to employ a carbon content far in excess 0! that emby quenching from temperatures as mgh as 2200 F. obtained a hardness as high as Rockr g e ni fie figae g m f g fi fi well C 67. This steel was also annealed to a the element vanadium because of its extremely hardness 255 Brineu' at which hardness it high amnity for carbn will form carbides in could be readily machined. The steel was readily the alloy large amounts 6; wmch Wm not go mm toregable and forged with about the same ease as would a 1.00% carbon tool steel.

solid solution at the normal hardening and forging temperatures. Even in the hardened state Heat No. 2 the improved steel will have a comparatively A heat of steel was prepared contaimng 3.05% gfig gi ggg which are embedded extretnely carbon, 1.01% silicon, .32% manganese, and

In my Patent No. 2,105,114, granted January 9.60% vanadium, which it was possible to harden to approximately Rockwell C '70 from 1600 F. 11, the fact was disclosed carbon and to Rockwell C from 20 0 F. This Steel contents up to 125% or 150% could be was annealed to a hardness of 255 Brinell, at ployed m molybdenum steels 85.1mm as thgre which hardness it could be readily machined. It was also present a vanadium content in excess likewise forged with the Same ease as a carbon of two and one-half to one and below three and tool Steel of about 1 00% carbon content 40 one-half to one of the carbon content. This Having made discovery that i the an important dlscovery' but to repeat it vanadium-carbon ratio was approximately that did not offer the wear resistance which forms the as given that Such a material could be readily subject matter of the present invention. What forged and annealed and hardened to extr em 81 y I have now discovered is that steels having carbon contents in excess of 1.25% and less than fig g g ;g;; :g: ?;g$ gzf 2: :35? Sig? about 3.50% carbon may be prepared as long as be 11 content of from about 1.25% to about 3.50%

the steel contains a vanadium content of apand a vanadium content of from about 3.00% to proximately three times the amount of carbon about 11 007 present. Accordingly, in an alloy steel of the Heat No 3 character under discussion having a carbon content in excess of about 1.25% and less than A heat of steel was made containing 3.10% about 3.50% the vanadium content would range carbon and 8.60% vanadium, to which was added from about 3.00% to about 11.00%. a tungsten content of 4.92%, and the material To repeat, steels containing about 2.50% carremained forgeable.

Heat No. 4

This heat of steel contained a carbon content of 2.94% and a vanadium content of 9.50%, to which was added 10.64% of tungsten. The material remained forgeable and was found to reside within the premises of the invention herein disclosed.

Two additional heats of steel were made containing 3.12% carbon and 10.10% vanadium, and 3.14% carbon and 10.10% vanadium, to which were respectively added 15.58% tungsten and 24.50% tungsten, but neither of these steels appeared to be commercially forgeable. It was therefore concluded that with the carbon on the higher side of the carbon range about 12.00% tungsten was the maximum that should be added inorder to maintain thematerial commercially forgeable. In order to determine the upper limit of molybdenum, heats were prepared constantly increasing the amount of molybdenum present and it was found that the material was not commercially forgeable in the higher carbon range after the molybdenum content exceeded about 10.00%. Molybdenum and tungsten were added to determine the upper combined limit of bothof these elements and it was found that as long as the combined amount of the two was under about 10.00% the material could be successfully forged, whereas if the combined amount exceeded this figure the material appeared to be no longer commercially forgeable.

Ingots were made of the base composition already described containing both tungsten and chromium, and also containing tungsten, molybdenum and chromium. With the chromium content as high as 5.00% and with the carbon content approximately 2.00% it was found that either tungsten or molybdenum, or both, could be added to a total percentage of approximately 12.00% and the material would still be commercially forgeable. It was found, however, that an ingot of 3.25% carbon, 8.90% vanadium, 10.79% tungsten, and 4.12% chromium forged with considerable dimculty, which would indicate that in the presence of about 10.00% of tungsten or molybdenum, or a total of both, that a chromium content higher than 5.00% could not be added and still obtain a commercially forgeable material. All of these compositions naturally contain varying amounts of silicon, generally less than 1.50%, and a manganese contentgenerally less than .75%, and additionally they also contain the customary small amounts of impurities of sulphur and phosphorus.

The purpose of adding other alloying ingredients to the base composition wasto alter the physical properties of the alloy so that the material would have red hardness or would retain its hardness up to temperatures of approximately 1100 F. Hardened material made of the base composition decreased slightly in hardness with an increase in tempering temperature, but the material containing tungsten and molybdenum, or both, with a chromium content of from 3.00% to 5.00% did not materially decrease in hardness when the quenched specimens were tempered as high as 1100" F.

Ingots were made similar to those to which tungsten, molybdenum and chromium were added, but with a lesser vanadium content; that is, with the vanadium content below 2.00%, and none of the ingots so made could be successfully forged, which is indicative of the fact that it is the presence of the carbon-vanadium ratio that permits the material to be forgeable.

The following table will additionallyserve to give information concerning a number of compositions which were prepared and is indicative of the manner in which the material forged:

Heat Si Mn W Mo Or Va Remarks 1186... 3.05 1.01 .32 9.60 Readllyiorgeable. 1137... 1.95 1.20 .35 512 D0.

1138... 3.10 .82 4.92 8.60 For eable. 1139... 2.94 .72 .37 10.64. 9.50 $0.

1140... 2.10 1.31 .31 4.72 5.30 Readllyiorgeable. 1141-.. 2.09 1.41 .29 10.47. 5.12 Do.

1144... 3.12 .72..-. 16.58 10.10 Notiorgeable. 1145.. 3.14 .90 .35 24.50 10.10 D0.

1147... 2.00 .96 .37 16.02 5.05 Raadilyiorgeable. 1148.. 1.90 .89 .38 23.87 5.05 Not forgeable. 1150... 1.99 .99 .40 10.47. 6.00 Forgeable. 1161.. 2.06 .83 .27 5.20 6.30 D0.

The following table shows the Brinell hardness that was obtained after annealing some of these materials at a temperature of 1650 F.:

Brinell hardness almr annealing Heat number HEAT 1136 Fracture Quenching temperature, F. grain size HEAT 1141 The following table shows the hardness obtained expressed in the Rockwell C scale on a few of the heats when quenched from different quenching temperatures:

Material made from heat 1161 after quenching from 2350 F. retained a hardness of 68 Rock- 15 well C after tempering for one hour at 1050" F., definite proof of the red hardness of some of the compositions to which tungsten or molybdenum, or both, and chromium were added.

Material made from heat 1136 within the range of the basic composition when quenched from 1600 F. and tempered at 1050" I". for 1% hours showed a hardness of 47 Rockwell C and when quenched from 2200' F. and tempered at 1050 F.

for 1% hours showed a hardness of 57 Rockwell C, which indicates that while the material had some red hard properties there was a noticeable drop in hardness when it was tempered at 1050 F. It also was found that material of the basic composition shows a resistance to abrasion of as much as 10 to 1 over that of carbon tool steel containing 1.00% carbon and hardened to a Rockwell hardness of C 67.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent of the United States is:

An improved iorgeable and machinable alloy steel, said steel containing from about 1.25% to trace up to about 5.50%, with the balance 01 the alloy substantially all iron.

' JAKE P. GILL.