US2034278A - Laminated metal stock - Google Patents

Description

March 17, 1936. BEKET AL 2,034,278

' LAMINATED METAL STOCK Filed April 19, 1934 IRON OR STEEL kn:- R ABLE- CHR u TEEL 11v VENT FREDERICK M. BECKE' RUSSELL FRANKS l atented Mar. 17, 1936 UNITED- STATES 2,034,278 LAMINATED METAL STOCK Frederick M. Becket, New York,

Franks, Jackson Heights, N. Y

and Russell assignors to Electro Metallurgical Company, a corporation" of West Virginia Application April 19, 1934, Serial No. 721,308 6 Claims. (01. 29-181) The invention relates to composite, laminated steel sheets, plates, tubes and the like; and refers more specifically to new and-improved laminated sheets, plates, tubes and similar articles com- 51 prising a body of ordinary corrodible iron or steel provided with a surface portion or facing of corrosion resistant chromium alloy steel.

Considerable effort has been expended in attempts to produce articles of this type, in order 10 to obtain a relatively. inexpensive material that is resistant to corrosion, and-meritorious commercial'products have been developed. However,

certain difliculties have been encountered in the fabrication and use of the known types of laminated articles, most of which difficulties are directly attributable to the marked tendency of fe'rritic chromium steels'containing about 2%,

to about 16% chromium to harden when rapidly cooled, air-cooled for example, from'theelevated 20 temperatures ordinarily required in rolling the material. The air-hardening characteristics of these chromium steels are so marked that during hot-working they must be handled rapidly, lest they cool rapidly to too low a temperature,

harden, and crack. In order to soften them, they must be annealed for several hours at the proper temperature and subsequently cooled very slowly from the annealing black heat. 4 Although f'erritic steels containing about 16%, to chromium do not air-harden to anythin like the extent to which the 2% to 16% chromium steels do and are not veryhard'inherently, they lack ductility and toughness in the hot-rolled state, and long annealing periods are required to impart satisfactory ductility..

.On the other hand, the ordinary carbon steels used as a backing or body material for these composite articles are readily softened within a rela- 40 tively few minutes when they areheated under I the proper conditions, and they do not exhibit air-hardening :tendencies. fabricated from ordinary carbon steel on oneside and ferritic chromium steel on the other show marked differences in hardness on-the two sides, because even after annealing the plain carbon steel is softer than the steel containing chromium.

In some instances, this is a result of the fact that long annealing periods cannot be employed for fully softening the chromium steel side, because in so doing the plain carbon steel side wouldbe badly oxidized. If the annealing is done in an inert or reducing atmosphere, this difficulty may be partially eliminated; 'but such special treattemperature almost to a" Laminated articles ment is by no means a complete'solution of the problem.

One result of the difference in hardness of the two sides of the laminated 'prpducts heretofore known is that during rolling to the desired thick- 5 ness the two materials are reduced by different amounts, which in some instances is a disadvantage.

'Further difficulties result from the radically different manner in which volumetric changes 10 take place in the chromium and carbon steels, respectively, upon heating and cooling. These effects may on 000 on adversely affect the bondbetween the two aterials, and there is a tendency for thin sheets of the laminated materials 15 to' curl. y

It is an object of the invention to obviate the above and otherdifiiculties in the fabrication anduse of laminated articles comprising alternate, laminae of chromium alloy steel and ordinary 2 carbon steel.

According to the invention, laminated articles are provided by affixing to a base or body .of iron or carbon steel a facing or surface layer of chromium alloy steel which is substantially less hard- 25 enable than those heretofore used for the purpose:

Suitable chromium steels include those described in our joint applications Serial Number 640,778, flied November 2, 1932, Serial Number 640,900 filed November 2, 1932, (now vPatent 30 1,954,344) and Serial Number 694,057, filed October 24, 1933-. a

One steel des ribed in' our said prior applications comprises about 2% to 30% chromium;

carbonin amounts up to 0.50%, but preferably 35 not over 0.2% in the steels containing about 2% to about 16% chromium and not over 0.3% in the steels containing'about 16% to 30% chromium; and titanium, the titanium content being at least about twice the carbon content, and being 40 not more than about four times the carbon content plus 1% (preferably 0.5%) of the total alloy; the balance being chiefly iron.

Another steel described in the-said applications comprises iron, chromium, carbon, and 15 columbium, the ranges of chromium and carbon being the same as in the case of the aboveidentified iron-chromium-carbon-tltanium steels, and the columbium content being at least about four times the carbon content and being not 50 greater than eight times the carbon content plus about 2% (preferably 1%) of the total alloy, the balance being chiefly. iron.

A third steel described in our said applications comprises iron, chromium, carbon, and vanadi- 55 about 0.1%; and at least about five times the carbon content but not over 1% of vanadium; the remainder chiefly iron.

The laminated article of the invention may be fabricated by cleaning a surface of a sheet, plate, or tube of iron or structural grade steel, cleannumbers of the mild steel being given as a range of a large number-of determinations made on several representative sheets. The hardness numbers of the chromium steel sides are averages of several number tained at several points on the surface of each set. The Erichsen numbers were obtained laminated sheets about 0.035 inch thick.

Analysesolsteels Rockwell Bhsrdness number Erichsennuin'ber Heated at Heated at Hosted in Heated at %or Ashot 150 0.4 900O.10 Asbot 7s00.4 oo=o.i0 rolled hrs. and min. and rolled hrs. and min. and sircoolod lll'woled .aircooled aircooled I V f 3-3,; 1: 4.3 8.4 0.0 3;}; No I ,g 2 0.1 0.2 0.1 3:}; la 4.: 0.0 1.0 81% l, Z? 0.9 9.0 as 8 n s.1 so 7.1- s I is ts u w an 310 23 I i; ,3; a0 a1 a0 moo 0.20 1.00 as as so i q 0.01 18 M2 ii-ea as as 0.0

ing a surface of a suitable piece of non-hardenable chromium alloy steel, fastening the two steels together with the cleaned surfaces in juxtaposition, and welding the said surfaces by hotrolling or forging in known manner. If desired, a thin sheet of soft iron, copper, nickel, or other softmetal, or a soft alloy, may be interposed between the said surfaces to aid in forming a secure bodying the invention, showing a bond; but such an expedient will not ordinarily be necessary.

Another method of making the article of the invention is to cast the corrodible base metalainst asurface of a sheet of non-hardenable chromium alloy'steel, and subsequently to hotroll or to forge the composite artiole.-

In the accompanying drawing, the sole time is a cross-sectional view of a typi article em- I eet of iron or mild steel united to a sheet of non-hardenable chromium steel.

The chromium alloy steel of decreased hardensbility forming the surface portion of the lamlnated article of the invention exhibifi in the asrolled state a surface hardness and thermal properties approachingthose of iron and ordinary steel much more closely than do the air-hardenable 2% to 16% chromium steel and the 16% to 30% chromium -steel heretofore used for the purpose. Moreover, the non-hardenable alloy steel may be fully-softened by an annealing treatment which consists simply in'heating the steel at a temperature in the neighborhood of.800 to 900 C. for a few minutes, five minutes to one-half hour for example.

' Comparative tests have been made of laminated sheets comprising single sheets of mild steel (0.07% carbon) united to single sheets of chromium steel free from titanium, columbium, and vanadium, and 'to single sheets oi non-hardenable chromium steels, respectively. "The followmg table includes representative data from these tests. Analysesaregiveninea'chcaseofthe metal on the side, and the mild steel side, respectively, the balance of the metal being substantially all iron. The Rockwell "B" hardness numbers were taken on each, side of laminated sheets 0.09 inch thick, the hardness vantages of simplicity and cheapness, and the articles of the invention possess none of the abovediscussed limitations and disadvantages of the laminated articles heretofore known; Further,

the articles of the invention possess other unique advantages: for example, they may be welded I thout excessive hardening, or cracking, and the hromium alloy steel will" be reduced in thick ness, during hot or cold rolling, at nearly the same rate asthe plain steel base, because of the similarity in'hardness and ductility of the two materials. Still further, the power consumption in rolling" thin sheets is reduced by the invention. 1 i

The corrcdible metal base may be an iron/a mild steel, or any steel ordinarily used for structural purposes, and may contain the relatively small amounts .of alloyed additions frequently added to structural steels to improve their The non-hardenable chromium alloy steel surface may for some purposes contain molybdenum and/or tungsten,,say up to about 3% molybdenum or up to about 5% tungsten.

The invention includes laminated articles of all shapes, including plates, sheets, rods, and

.tubes having a'bod'y of corrodible metal and one or more surfaces of corromon resistant steel, and

Variations and equivalents of the invention here-,-

in described will readily occur to. those skilled in the art, and such variations and within the spirit of the invention.

We claim:

quivalents are 1. Laminated articles whichmaybehotorcold worked in these-me manner as asolid mild steel article and consisting of at least one lamina composed of mild steel and at. least one composed of asubstantially non-hardenable chromiumalloysteelcontainingabout2% to80% chromium; carbon'ln amounts up to about 0.5%: and substantial amounts of additional metal which '75 tends to decrease the effect of the carbon, said additional metal being at least one of the group consisting oi." columbium, titanium, and vanadium; the remainder'principally iron; all of said lamina; having'similar hardness, ductility, and expansion characteristics during heating and cooling, and undergoing similar reductions in thickness when hot worked.

2. Laminated articles which may be hot or cold worked in the same manner as a solid mild steel article and consisting of at least one lamina composed of mild steel and at least one lamina composed ot a substantially non-hardenable steel containing about 2% to 30% chromium; carbon in amounts up to about 0.3%; and titanium, the titanium content being at least about twice the carbon content but not more than about four times the carbon content plus 1%; the balance principally iron; all of said laminae having similarhardness, ductility, and expansion characteristics during heating and cooling, and undergoing similar reductions in thickness when hot worked.

3. Laminated articles which may be hot or cold worked in the same manner as a solid mild steel article and consisting of at least one lamina composed of mild steel and at least one lamina composed of a substantially non-hardenable steel containing about 2% to 16% chromium; carbon in amounts up to about 0.2%; and titanium, the titanium content being at least about four times the carbon content but not more than about four times the carbon content plus 0.5%; the balance principally iron; all of said laminae having similar hardnesa'ductiIity, and expansion characteristics during heating and cooling, and undergoing similar reductions in thickness when hot worked.

4. Laminated articles which may be hot or cold worked in the same manner as a solidmild steel article and consisting of at least one lamina composed of mild steel and at least one lamina composed of a substantially non-hardenable steel containing about 2% to 30% chromium; carbon in amounts up to about 0.3%; and columbium, the columbium content being at least about four times the carbon content and being not greater than about eight times the carbon content plus about 2%; the balance principally iron; all of said laminae having similar hardness, ductility, and expansion characteristics during heating and cooling, and undergoing similar reductions in thickness when hot worked.

5. Laminated articles which may be hot or cold worked in the same manner as a solid mild steel article and consisting of at least one lamina composed of mild steel and at least one lamina composed of a substantially non-hardenable steel containing about 2% to 16% chromium; carbon in amounts up to about 0.2%; and columbium, the columbium content being at least about eight times the carbon content and being not greater than eight times the carbon content plus about 1%; the balance principally iron; all of said laminae having similar hardness, ductility, and expansion characteristics during heating and cooling, and undergoing similar reductions in thickness when hot worked.

6. Laminated articles which may be hot or cold worked in the same manner as a solid mild steel article and consisting of at least one lamina composed .of mild steel and at least one lamina composed of a substantially non-hardenable steel containing about 3.5% to 20% chromium; carbon in amounts up to about 0.1%; and at least about five times the carbon content but not over 1% vanadium; the remainder chiefly iron; all of said lamina: havingsimilar hardness, ductility, and

expansion characteristics during heating and cooling, andundergoing similar reductions in thickness when hot worked,

FREDERICK M. BECKET. RUSSELL FRANKB

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