US2403141A - Chrome beryllium alloy steel and articles of manufacture produced therefrom - Google Patents

Description

Patented July 2, 1946 CHROME BERYLLIUM ALLOY STEEL AND ARTICLES OF DIANUFACTURE PRODUCED THEREFROM Enrique G. Touceda, Loudonville, and Ralph P. De Vries, Menands, N. Y., assignors to Allegheny Ludlum Steel Corporation, a corporation of Pennsylvania No Drawing. Application July 28, 1942, Serial No. 452,639

reason for this is believed to reside in the unfavorable fluidity characteristics of such steels and another in the unsoundness of the products produced. While considerable improvement has been made along these lines, we have discovered that we can in a relatively simple manner greatly improve the fluidity and soundness of this type of composition.

One of the objects of our present invention is to provide alloy steels which have unusual and outstanding characteristics in that they are admirably adapted for casting purposes and especially for intricate castings which cannot be produced from regular chromium or rustless steels.

Another object of our invention is to produce chromium alloy steels having beryllium and copper additions thereto, thus producing a series of new, useful and highly desirable alloy steels having varied industrial applications.

A further object of our invention resides in the production of beryllium-copper-chromium alloy steels having a low fluidity point which closely approximates that of cast iron, whereby pressure castings of such alloy steels can be simply and readily made in direct contrast to prior compositions.

A still further object of the invention resides in the production of beryllium-copper-chromium alloy steels which can be endowed with desired properties of hardness and ductility and which can be employed to advantage both in the as cast and in the rolled condition for a variety of useful purposes.

Other and further objects and advantages will be understood by those skilled in this art or will be apparent or pointed out hereinafter.

The chromium alloy steels are comparatively difiicult to form into pressure castings due at least in part to the fact that their fluidity point is high. As compared with our new compositions the chromium alloy steels do not have particularly good wearing properties and they are not easily machinable. In addition, these steels are relatively expensive to produce and this is 8 Claims. (Cl. -125) a limiting factor where cost is an important item.

Our present invention is predicated upon the discovery that chromium and silicon alloy steels containing from about .5-14% of chromium and about .5-4.5% silicon in combination with relatively small amounts of beryllium and copper constitute new and highly valuable compositions. As will be explained more in detail hereinafter, alloy steels responding to the ranges of composition hereinafter set forth and claimed have new and highly useful properties and characteristics not shared by compositions which do not respond thereto and thus we provide a whole series of alloy steels which not only excel known chromium alloy steels but which open up new fields of application.

Our new alloy steels are composed of the following constituents in approximately the following amounts:

Per cent Carbon .05- 2.00 Chromium .5 -14.00 Copper .5 6.00 Silicon .5 4.50 Beryllium .05- .30

other articles of manufacture such as rolling mill products, gages, gears, pistons, valves and various structural members. The particular properties and characteristics of our new compositions and articles fabricated therefrom will be best understood from the following examples taken in conjunction with the tables hereinafter set forth and commented upon. It is to be understood that these constitute examples and thus do not serve to restrict the invention.

1 Reference is first made to TableI, which fol- OWSI practically the same as that of cast iron.

Table I Fluldity Melt N C Cr S1 C0 B0 N1 Mn Cu N point 111 F 0. 55 13. 50 3. 50 2. 00 2, 450 48 12. 60 3. 75 2. 00 2, 475 55 12. 50 3. 75 2. 00 2, 450 55 12. 50 3. 50 2. 00 2, 475 52 12. 50 3. 50 1. 50 500 .40 15.50 2.50 2.00 2,475 .10 13.50 2.50 2.00 2,500- 12 50 l. 2.00 2, 475 .05 12.50 5.75 2.00 2,450 .50 5.00 .50 200 2,450 .50 2. 00 .50 4.00 2, 450 .45 1.00 2.50 4.00 2,500 2. 50 4. 00 2, 500 50 50 2. b0 4. 00 2, 500 13.50 3.50 2.00 2,425 1. 00 1a. 50 a. 50 2. 00 2, 425 0 l. 50 13.60 3. 50 2. 00 2, 350 A-342 50 2. 00 50 2. 00 2. 500

In this table we have 1ncluded some tymcal It will be noted that all compositions of Table compositions and the fluidity point of each. The expression fluidity point as used herein means the temperature at which the composition desig- 1 nated will remelt and flow well in castings. This point was determined by making finished castings of the compositions specified of diverse shape 3 and section with particular emphasis upon the ability of the composition to fill the mold in Compositions creasing carbon contents in still further lowering the fluidity point and when an amount of carbon is employed which approaches the maximum of about 2% the alloy steel has a fluidity point This is highly advantageous since it enables pressure castings to be made simply, readily and at rea- I contain both beryllium and copper and that some of these compositions, for comparative purposes, also contain one or more of the following in the approximate amount specified: nickel, cobalt, manganese and nitrogen. Data of Table I and other tests carried out by us demonstrate that the addition of such elements as cobalt, manganese and nitrogen is not necessary and has no observable effect. Nickel may be employed as an optional constituent of our compositions up to about 1%, and in some cases up to about 3%, but is not an essential component of our new alloy steels and may be utilized in those cases in which it does not interfere with the abrasion hardness obtained by heat treating operations. When employed in these proportions, nickel has no adverse effect on casting properties.

Reference is next made to Table II, which folsonable cost. 40 lows:

Table II Transverse test of d cast $4 and 94" Unnotched impact Heat treatment gx gi File 4 F, p. s 1 Bend Ft. lbs. Bend Degrees Degrees A-54 29 H 139, 200 2 47 H 185, 700 1 43 H 170, 000 5 32 H 139, 200 19 A-104 42 F 55 H 59 H H 46 F 42 F 24-342 58 H 128, 000 0 51 H 244, 000 0 51 H 164, 800 0 1,600 01L. 60 H 141,600 0 1,700 oil 60 H 136, 800 O A-343 AS 09st 58 H 138, 000 0 1,400 F 01] 35 F 281, 600 8 134 1,500 011-." 40 F ,500 1 1,500" 54 H 218, 400 0 1,700 oil- 55 H 171, 200 0 11-38 As cast. 37 B 122,000 a 2,l00 01 39 H 122, 700 10 2,150 01.1 as H 124, 800 5 A-39 A5 cast.- 43 H 152, 700 0 2,100 oil. 48 H 000 3 2,150 Oil 37 H 155, 000 6 44-40 As cast 49 H 151, 800 0 2,100 01L 54 H 127, 500 2 2,150 511 45 H 168,000 5 44-452 2,150 oil 750 30 H 112, 000 9 44-453 1,750 oil 750 40 R 278, 000 142 F=fibre stress on extreme fibre in pounds per square inch.

chromium content in the upper portion of the specified chromium range may be used in the as cast condition and in such condition can be given substantially file hard wearing surfaces with good ductility as will be understood from the degree of bend obtained in a transverse test-as set forth by said table. These alloy steels are largely austenitic as cast and the austenitic condition can be insured and rendered more stable and uniform by an austenitiaing heat treatment from a temperature of about 1800-2200 F. Castings produced therefrom possess increased duetility without loss of file hardness. That these alloy steels are austenitic is corroborated by the fact that they are practically non-magnetic.

Composition A-104 of Table II when drawn in the range of 850-950 F. from the 2100" F. oil quenched state becomes fully file hard with a Cone Rockwell hardness of approximately 60 and therefore is useful for the production of cast articles such as gages.

Compoosition A.-343 of Table II shows that'after a 1400" F. oil quench the composition is capable of a 20 bend with an unnotched Izod impact value of 134 foot pounds and a 40 bend with an unnotched Izod impact value of 250 foot pounds. When this composition is tested statically in the transverse test it shows bend as indicated by the table but in the unnotched impact state shows excellent degrees of bend with very high impact strength as already mentioned. This is a remarkable and highly unexpected characteristic of our new beryllium-containing alloy steels throughout the higher chromium range specified irrespective of whether those steels are high chromium steels heat-treated from a temperature of about 1900-2100'F. or a somewhat lower chromium steel quenched from a temperature as low as 1400-l500 F. The fact that all these steels have high strength and good ductility when subjected to suddenly applied loads increases their usefulness very considerably and enables these steels to be used in many environments where they are likely to be subjected to suddenly applied strains and under such conditions that they withstand those loads and strains in contradistinction to known steels which do not share this property.

For example, we have cast sections 4" x 4"- with a carbon content of about 1.5% and subsequently machined gear teeth on those sections having a cross-sectional area of x 4" at the base of the teeth. Even these high carbon alloy steels in the as cast condition machine well after a sub-critical anneal of 13'50 F. Examination of such gear teeth when broken under impact shows that even large cast sections with a high carbon content are capable of withstanding great shocks when they have a composition responding to our present invention.

With a carbon content of .30% or more and a chromium content in the upper portion of the specified chromium range our new alloy steels both as cast and in the rolledcondition exhibit file hard surfaces in conjunction with high resistance to shock after an austenitizing heat treatment to such extent that they approach the ideal desired in this respect and this property is not seriously impaired if the fully austenitic com- 5 position is drawn back within the range of 450- 900 F. when the chromium content ranges from about 10-14% with a carbon content ranging 6 1 a from about .05-.30%, both the file hardness and the wear resistance progressively decrease with increasing chromium and carbon percentages but these alloy steels have materially increased ductility making themadmirably adapted for structural purposes. Steels with the lower carbon contents and the higher chromium contents can, therefore, be heat treated from a temperature less than 2100 F. Composition A453 is an example of this type and such steels can be processed precisely like those having a chromium content in the lower portion or the specified range.

Additional properties of our new alloy steels are illustrated by Tables III and IV, which follow:

Table III File Fluidg g 0 01' Si Mn Ni Cu .01 Ag Be hardity ness point 11:212.- 1.2313.502.000.500 502.00. 0.10 -11 2,300 11-273-.. 1.0013.502.00 .50---. 2.00 .10 H 2,300 A-274. 1.0013.s02.00 .50 .-4.00 .11- H 2,400 A275.. .0013.503.00 .50-.-.250 s 12,500 A-276. .00 8.001.50 .50 .4.s0 .18 s 2,475 A-277. .00 8,001.50 .50 -..4.50 .18 8 2,400 A-278. .1.00 3001.30 .50 ..4.50 .18 H 2,475 21-270. .3012.30a.002.25....2.00 .08 H 2,000 A-280.-. .5012.502.002.25 .1.s0. .00 H 2,500 A-28l .501250225225. .1.15. .01 H 2,500 21-282; .50 1250125225--.- 2.00 .08 H 2,415 21-255..- .0513.503.75 .5o1.002.00.. .08 2,450 A256.. 11.113.503.75 .501.002. 00- .08 2,415

1 Did not melt or flow. H=Hard. i S=Sol't.

Table IV Fibre Melt Bend 3 Rock- File heat ff f fg in State well hardf No. i degrees cone ness A272 102,000 4% As cast. 31 111110-. NM 11-213-.. 134,000 d 35 do NM 11-274"... 152,000 33 do NM A275. 138,000 :13 -00-.- NM 21-276... 118,000 48 "-00.- M 11-217..-" 120,000 43 ".40... 5M A478"-.- 02,000 52 do.- M 11-279..-" 130,000 34 d0 NM 11-200--.. 14,400 28 .do NM A28l 150,000 31 N A282 132,000 23 do NM A255. 222, 200 0 45 n M 1 1-253"... 100,000 a as do M 1 1-250"-.- 217,000 0 Ascast 4s -00... M 1.250..." 113,000 2,130011 41 -110... M

Alloy steels having a chromium content in the low and middle portions of the specified chromium range do not respond to the high temperature austenitizing heat treatment as well as those havinga greater amount of chromium and thus the former must be quenched from a much lower temperature. In this connection a temperature range from about 1400 F. to about aluminum while still obtaining a fluidity point below 2500 F. Compositions A-279,'A-280 and A-281 show that the use of silver contributes nothing to the compositions and in general the use of aluminum and silver are of little or no value and form no essential part of our present invention. Composition A-280 with the least amount of silver and with the lowest amounts of beryllilun and copper showed the best casting properties of any of these three compositions 1A 279, A-280, A-281). It will be further noted that these compositions contained more man-- ganese than the other compositions and this indicates that a moderate amount of manganese in tha neighborhood of that set forth in Table III can be usefully included when the silicon, copper and beryllium percentages are at or near the lower portion of their specified ranges but, unless otherwise indicated, the manganese content did not exceed .50%.

These compositions are all fine grained in the as cast condition except that A-277 and A-2'78 are slightly dendritic. It is a general rule that these steels are difficult to distinguish from rolled steels even in the as cast condition because of their fineness of grain size.

All the medium and most of the high carbon steels throughout the entire chromium range specified can be forged and rolled and when so treated have even greater strength and ductility than in the as cast condition.

The following test illustrates comparative surface wear characteristics: a piston for an automatic operating valve controlling the flow of water was made from a steel containing .55% carbon, 13.5% chromium, 3.5% silicon, .50% manganese, .75% cobalt, 2% copper and .09% beryllium. This steel was heated to 2000 F. and quenched in oil. The wearing surface was lapped before the test was carried out and then this piston was automatically operated under accelerated test conditions for a period of one month which was equivalent to an actual service period of seven years. During the month test the wear of the surface of this valve was measured against and compared with that of a second piston composed of austenitic stainless steel containing 18% chromium and 8% nickel and a third piston composed of Monel metal. The amount of leakage of water past the piston was taken as the measure ofwear. All three pistons were of a non-corrosive type of material. The piston having the beryllium-copper analysis above set forth showed up best as compared with either of the two higherpriced compositions. Consequently articles like pistons, valves for food canning machines and many other articles for varied services can be cast to size, in many cases requiring only a slight grinding on the wearing surfaces. This results in substantial savings and for articles like a steel valve having a number of orifices the saving is especially worthwhile.

Steels responding to our invention and having a chromium content ranging from about 3% to about 8% are largely magnetic even in the as cast condition and therefore they belong to that class which is not quenched from a high temperature but from a temperature in the range of about 1400-1800 F. as set forth above. This is confirmed by the higher hardness values reached on cooling in the as cast form as shown in Table IV. These steels have somewhat less ductility in the as cast condition as will be observed from the amount of bend in the transverse test.

The foregoing is illustrative and not limitative and various additions, omissions, substitutions and modifications may be made therein without departing from the spirit and scope of our invention as defined by the appended claims.

Having thus described our invention, what we claim as new and desire to secure as Letters Patent are:

1. An alloy steel composed of about .05-2.00% of carbon, about .5-14% of chromium, about .5- 6% of copper, about .54.5% of silicon, and about .05.30% of beryllium, the balance being substantially all iron except for the usual impurities in common amounts.

2. An austenitic chromium-copper-beryllium alloy steel composed of about 10.0%14% of chromium, about .052.00% of carbon, about 1.56% of copper, about .5-4.5% of silicon, and about .05-.30% of beryllium, the balance being sub-' stantially all iron except for the usual impurities in common amounts.

3. Articles of manufacture characterized by high strength and good ductility when subjected to suddenly applied loads which contain as essential elements thereof an amount of copper ranging from about 1.5-6%, about .05-.3% beryllium, and about .5-14% chromium, the balance being predominantly all iron except for about .05-2% carbon, about .54.5% silicon and the usual impurities in common amounts.

4. An article of manufacture composed of an alloy steel having a fluidity point approaching that of cast iron and composed of about .5% carbon, about 12-14% chromium, about 2.5-3.5% silicon, about 2% cop-per and about .1% beryllium, the balance being substantially all iron except for the usual impurities in common amounts.

5. A ferrous alloy including, among other alloying constituents, carbon from about 1% to about 2%, chromium from about 8% to about 14%, silicon from about 2% to about 4.50%, copper from about 2% to about 6% and beryllium from about 0.05% to about 0.30% and characterized by a melting point approaching that of cast iron.

6. A ferrous alloy containing, among others, the following alloying constituents: carbon from about 0.50% to about 2%. chromium from about 8% to about 14%, manganese in the neighborhood of about 2.25%, copper from about 1% to about 4%, beryllium from about 0.05% to about 0.30% and silicon in the neighborhood of about 2%, and characterized by fineness 0f grain size in the as cast condition.

'7. A ferrous alloy characterized by having a fluidity point below 2500 F. and by being highly resistant to impact strains, containing from about 0.05% to 2.00% carbon, from about 6.00% to about 14% chromium, from about 1.50% to about 6.00% copper, from about 0.50% to about 3.50% silicon and from about 0.05% to 0.3% beryllium, with the remainder substantially all iron except for the usual impurities in common amounts.

8. A ferrous alloy characterized by having a fluidity point below 2500 F. and by being highly resistant to impact strains in the ascast state, containing from about 0.30% to about 2.00% carbon, from about 6.00% to about 14.00% chromium, from about 1.5% to about 6% copper, from about 0.50% to about 3.50% silicon, from about 0.05% to about 0.3% beryllium and from about 0.50% to about 2.25% manganese.

ENRIQUE G. TOUCEDA. RALPH P. DE VRIES.