US2006304A - Alloy steel - Google Patents

Description

Patented June 25, 1935 UNITED, STATES PATENT oFncE ALLOY STEEL Jerome Strauss, Pittsburgh,-

mesne assignments, t

Pa., assignor, by U. S. Bu'stless Steel &

J Iron Corporafi n', Brldgeville, Pa... a corpora- 1 tion of Delaware. No Drawing. Applicati on Aprll' 13, [1935, Serial No. 16,255. more Britain June 16, 1934 This invention-relates to 9.11037 steels, andmor'e particularly to' chrome steels containing less than 2% of chromium, together with copper, silicon and phosphorus. In the term steels I include 3' the low carbon steels commonly referred to as her 8, 1933.

Chromium than the stainless steels are commonly divided 6 the capacity hearth furnaces in large tonnage-to give a clean ingot irons, which, because of their process of manufacttfi e, are steels of the lowcarbon variety.

This application is a continuation in part "of my application Serial 110,701,537, filed Decemsteels containing less chromium into two classes; (1) .those containing less than in the first class is not as good as those in the reater difficulty in hot second class. However, as the chromium is increased above about 2%, the steel becomes not only more costly to make, but difficulties are encountered in making and fabricating, such as working, greater airhardening, less ductility, and greater tendency for inclusions and seams. These difliculties'increase progressively as the chromium content increasesin this higher range. Steels of this second class which lie between the readily'workable steelsof theifirst class and the stainless steels, have not found wide application'because their resistance to' corrosion, which-ls greatly inferior to that of, the stainless steels, has not "been sufllcient to compensate for theirincreased cost in manufacture and fabrication over the steels of the first class.

The present'inventionrelates to the first class of steels, and to their improvement, particularly in corrosion resistance, by the addition thereto 1 o! phosphorus'in conjunction with copper' and silicon, all in-the ran'gesand proportions'herein- '1 after pointedout.

The effect of phosphorus on carbon steels and 50 many alloyste'els'is well known and its influence.

is regarded as a detrimental.one,'so that in most steel specifications an'upper limit for the phosor 350%, depending upon the remainder of the -56 composition of the steel and. the purpose for which it is to' be used. Bessemer steels with their high phosphorus content have been regardedas.v inferior in many respects to lower phosphorus steels made by the open hearth, crucible or electric. furnace processes. Among the detrimental influences of phosphorus have been (1) the hardening of steels which makes them objectionable for cold-forming and cold-drawin operations; (2) the development of coldshortnessor ease of rupture when mechanically worked at atmospheric orlslightly elevated temperatures, to a degree all out of proportion to the higher hardness, which cold-shortness makes them still more objectionable for cold-forming I and cold-drawing'operations; and (3) the segregation of phosphorus in the'ingots into which'the steels are cast prior to hot working, or in other cast forms, resulting in great non-uniformity of properties throughout the cast or wrought. body of steel.

to chromium-copper silicon steels of the first class greatly improves their resistance to corro;

sion by the atmosphere and other corrosive media, without impairing their workability and "mechanical properties. In some casestheir workability may be actually improved by the increased phosphorus. While, as above noted, phosphorus is highly detrimental in its effect upon most steels, I have found that steels containing the .chromium-copperesilicon combine tion within the'ranges hereinafter specified are an exception, and .that the phosphorus does not have its usual-deleterious cast or wrought condition. I have found that a very. small amount of phosphorus has a remarkably large eflect upon corrosion resistance. For

example, asteel containing approximately .06%

carbon, .90% chromium, '.45% copper, .'l5% silicon, and .12 %Ypho'sphorus possesses resistance to atmospheric corrosion about equal to that .of a steelcontaining the same carbon, copperand .silicon contents, but. with 1.85% chromium and- The addition of a small .03% phosphorus.

the phorussteel of higher-chromium content and e resistance to -fcorrosion. as a low phos- :more readily-workable, or produces one with increased resistance ,tocorrosion with the same chromium content:

per-silicon steels containing less than 2% chro- 'mlum and up to about 115% phosphorus are examount of phosphorus produces a steel having '20 I have found thatthe addition of'phosphorus efiects in either the one which is therefore cheaper and ismoreover I have found that-low carbon chromium-copv tremely ductile amyreadily workable hot and cold. This is contraryto previous experience with other steels of high phosphorus content. Moreover, in such steels the phosphorus content appears. to-segregate to a much smaller degree than in carbon steels 01' like carbon content. As

the test "pieces, the tensile strength, the yield point, the elongation and the reduction in area. It is to be noted that not onlydo these steels exhibit a resistance to atmospheric corrosion at least three times that of a plain carbon steel of 5 illustrative of the good ductility of such steels, like carbon content, but in addition they are rea steel containing .02% carbon, .94% chromium; markably strong and ductile. Ordinarily in steels .31% copper, .63% silicon and .54% phosphorus of low alloy content, it is difficult to obtain these was bent flat upon 'itseli without fracture and three qualities simultaneously. 10

I Tensile Yield j I Reduction 0 Mn Si Cu Cr P lilmenslons and conditions strength point Elongation in mm I f in. f a in. Per tint in. Per ml! 1 0.00 0.30 0.84 2.73 1.42 0.19 34 plate asrolled 80950 70050 30.0 65.3 2 0.04 0.20 1.22 0. 40 1 00 0.20 94" plate as rolled 73000 50100 35.5 05.5 3 0.04 1.24 1.10 0.33 0.21 }iplateasroiled 77250 01900 34.5 00.4 4 0.10 0.20 0.02 0.45 1.00 1 0.00 W plate as rolled-. 01100 53500 34.5 054 5 0.00 0.30 0.70 0.87 1.00 0.18 002 sheet annealed. 02250 40750 10.0 0 -0.07 0.22 0.08 0.87 0. 24 0025" sheet annealed- 40500 10.5 7 0.05 0.28 0.71 0.51 0.95 0. 0.025" sheet annealed- 57900 39550 24.0 s 0.05 0.28 0.58 0.30 0. 93 0.53 0.025"sheet annealed- 74050 54500 21.5 0 0.00 0.25 0. 75, 0.45 0.74 0.12 splateasrolled 71500 59200 30.5 10 0.00 0.25 0.75 0.45 0.74 0.12 54 0055 annealed- 00000 50400 40.0 11 0.10 0.29 0. 39 0.50 1.14 0. 21 95"plateasrolled- 86800 00000 55.0 12 0.10 0.20 0.89 0.50 1.14 0. 21 %plate annealed 03200 05200 34.2 13 0.06 0.25 0. 75 0. 45 0.74 0.12 .025" Sheet as rolled -81600 70700 16.5 14 0. 00 0.25 0. 75 0.45 0.74 0.12 .025" sheet n0rmalized 70000 50200 27.5

then the double thickness was bent again at right angles to the first bend also without any fracture .even at the corner of the double bend.

While I find that chromium-copper-silicon steels of the first class above referred to are greatly improved if they contain from .07 to 375% phosphorus, I preferto use from .09% to .30%, and more particularly from .09% to .20%

. phosphorus. For best resistance to corrosion, the carbon content should be less than about .30%,

' from .15% to.3%, the upper limit of the copper being preferab1y .60%. The preferred range of 1 copper. is about .30% to .50%. The silicon may vary between 25% and 3%, usually between .25% and 2%, the preferred range being between .50%

.5 and 1.50%. The manganese and sulphur are maintained low, the manganese not exceeding .50% and thesulphu'r not exceeding .10%. The

manganese may vary between .02% and'.50%,

preferably from .10% to .35%. The sulphur preterably is not over .06%. The balance 01' the steel is substantially all iron, by which 1 mean that other alloying elements are not employed in amounts to deleteriously afiect the desired corrosion resistance and/or mechanical'properties,

00 .although small amounts of, say, a fraction of a 66 steel within the broadest ranges which per cent of one or more of the usual steel making alloying elements may be present, such as nickel, molybdenum, vanadium, etc. Although excellent results are obtained from given, the best results, takingv into consideration all of the various i'actors such as resistance to corrosion, tensile strength, ductility and ease of fabrication, are obtained when the elements chro- !0 mium, silicon, copper and phosphorus are present,

mpectively, in the proportions of about 656:3:1. The following table illustrates examples of steels made in accordance with the present invention. The table gives the composition of the have been The sulphur in each exceed .10%.

A steel containing Carbon; L .01%to .30% Chromium 3% to less than 2% Copper 9 .15% to 3% Silicon .25% to 2% Phosphorus .07%..to .30% Manganese -Q. .02% to .50% Sulphur not over .06% Balance substantially all iron,

01 these'st'eels does not is characterized by a tensile strength in a rolled and normalized condition of about 50,000 to 90,000pounds per sq. in., a resistance to atmos- Phosphorusaua 10% to 20% Manganese Q. .10 to 35%; Sulphur not over .06% Balance substantially all iron,

-pheric corrosion of about two to seven times is characterized by having a tensile strength a rolled and normalized condition greater than 65,000 pounds per sq. in., a resistance to atmospheric corrosion'at least three times that or a plain carbon steel of like carbon content, and

a deformability at room temperatures at least equal to that 01 plain-carbon steel of equal ten- ,sile strength, and iurther characterized by high resistance to impact at temperatures as low as 40 F. and; by low hardening capacity on air cooling.

Alloy steels having high physical properties, as well as high resistance to corrosion, may be made in either castor wrought form in accordance with the presentinvention. If any element which is used for the purpose of bringins about resistance to corrosion tends to deleteriously elect the mechanical properties of the steel, it is oiiset by other elements which impart 15 corrosion resistance and which also tend to counteract these undesirable mechanical properties. For instance, the deleterious properties due to a high content of phosphorus are entirely counteracted by the presence with the highphosphorus content of a definite combination of chromium, copper and siliconin the ranges herein specified. By the simultaneous use of all these elements, non-corrodibility and high'physical properties are. brought about without the presence or manifestation of arm of the deleterious-properties. For instance, the ability of phosphorus to impart corrosion resistance and machinability to steel is utilized withoutfany manifestation of cold-shortness or brittleness. As the high physical properties, machinability, ductility, and ease of fabrication are obtained by-theelements as specified above, the presence of any other elements in appreciable percentages becomes entirely superfluous. It is known that manganese in high percentages is used for imparting .strength,and sulphur for imparting free vmachinability to steel. In the balanced comnecessary to increase the percentages of the noncorrosive elements to counteract any deleterious properties that would be brought forth by the manganese :and sulphur contents;

The steel of the present invention has high strength and ductility, high resistance-to impact, effective resistance to mild corroding media, and, inadditiom'low air hardening capacity so that it may be subjected to the usual operations incident to'hot forming and welding without sufiicient hardening and consequent loss 01 ductility to require heat treatmentprior to structural application. The particular combination of non-co osive elements in the definite limits set forth above, therefore, produces a steel which is of a comparatively low alloying content with the attendant advantages of cheapness and ease of manufacture, and possessing the necessary desirable qualities otmon-corrodibility and high physical strength produced by the non-corrosive elements themselves. v

Wrought alloy steel articles made accordor alkaline reactions, natural waters including sea water and mine water, etc. The alloy can be made.

into castings or fabricated into wrought: a'rticles such as plates, sheets, structural shapes, tubing, wire, which are to be used where corrosion resistance is desired, as; for example, in ship building, railroad car making, transmission towers, bridges, etc.

The present invention is-not limited to the proportions set forth in the illustrative embodiments, but may be otherwise embodied within the scopeof the following claims. I

Iclaim: I 1. alloy steel containing .01% to bon, ..3% to less than 2% chromium, 15% to 3% copper, 25% to 3%' silicon, 07% to .'l5

.60% carphosphorus, .02% to, .50% manganese, and not over .10% sulphur, the balance'beingsubstantially all iron.

2. An alloy, steel containing .01% to .30% carbon, .3% to less than 2% chromium, .15% to .60% copper, 25% to 2.0% silicon, .09% to .30% phosphorus, .02%' to 50% manganese, and not over .06% sulphur, the balance being substantially all iron.

3. An alloy steel containing .01% to .15% carbon, .50% to 1.50% chromium, .30% to .50% copper, 50% to 1.50% silicon, .09% tor.20% phosph rus, .10% to .35% manganese, and not over .0 sulphur, the balance being substantially all,

iron.

. t 4. An alloy steel containing .01% .to .30% carbon, .3'% to less than 2% chromium, .15% to 3.0% copper, 25% to 2.0% silicon, .07%" to .30% phosphorus, .02% to 50% manganese, and, not over .06% sulphur, the balancev being substantially all iron, the alloy steel being characterized by a tensile strength in a rolled and normalized condition of about 50,000 to 90,000 pounds per sq. in., a resistance to atmospheric corrosion of about two to seven times that of a plain carbon steel of like carbon content, and a deformability ,at roomtemperatures at-least equal to that of plain carbon steel of equal tensile strength.

. 5. 'An alloy steel containing .03% to-.15% carbon, 50% to 1.50% chromium, .30% to 60% copper, .50% to 1.50% silicon, .10% to .20% phosphorus, .10% to .35% manganese, and not over .06% sulphur, the balance being substantially all iron, the alloy steel being characterized by having a tensile strength in a rolled and normalized condition greater than 65,000 pounds per'sq. in.,. a resistance to atmospheric corrosion at least three times that of a plain carbon steel of like carbon content, and a deformability at room temperatures at least equal to that of plain carbon steel of equal tensile strength, and further characterized ,by high resistance to impact at temperatures as low as 40 -F.-and by low hardening capacity on air cooling.

JEROME STRAUSS.

CERTIFICATE or CGRRECTlO N. Patent No. 2,006,304. June zs. 103s,

' JEROME STRAUSS.

lt is herehy certified that error appears in the printed specification of the above numbered patent requiring correction 'as follows: Page 2, second column,- line 15, in the boxed table under the heading ElongationVforVPer cent in." read Per centin 2 in.;' and that the said Letters Patent -should be read with this correction therein that the same. may conform to the reeord of the case in the Patent Office.

Signed and sealed this 13th 'day of Au'gl st, D. 193,5.

Leslie Frazer (Seal) Aeting Commissioner of Patents.