Laminated metal stock

F. M. BECKET ET AL

LAMINATED METAL STOCK

Filed April 19, 1934

March 17, 1936

2,034,278

RON OR STEEL

<img file="US2034278A_D0001.tif" />

NON-HARDEN ABLE CHROMIUM STEEL

INVENTORS

FREDERICK M. BECKET RUSSELL FRANKS BIT u ' iriZITTORNEY

Patented Mar. 17, 1936

2,034,278

UNITED STATES PATENT OFFICE

2,034,278 laminated metal stock

Frederick M. Becket, New York, and Bussell Franks, Jackson Heights, N. .Y., assignors to Electro Metallurgical Company, a corporation of West Virginia

Application April 19> 1934, Serial No. 721,308

Claims. (Cl. 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 com5 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 to obtain a relatively, inexpensive material that is resistant to corrosion, and meritorious commercialproducts have been developed. However, certain difficulties 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 ferritic chromium steels' containing about 2%. to about 16% chromium to harden when rapidly cooled, air-cooled for example, from the elevated 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 ^te“P^erat?re> 25 harden, and crack, m order to soften them, they must be annealed for several hours at the proper temperature and subsequently cooled very slowly from the annealing temperature almost to a black heat. , . . .. i cw

Although ferritic steels containing about lb % to 30% chromium do not air-harden to anything like the extent to which the 2% to 16% chromium steels do and are not very hard 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 relatively few minutes when they are heated under the proper conditions, and they do not exhibit air-hardening tendencies. Laminated articles fabricated from ordinary carbon steel oh one side and ferritic chromium steel on the other snow 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 would be badly oxidized. If the annealing is done in an inert or reducing atmosphere, this difficulty may be partially eliminated; but such special treatment is by no means a complete solution of the

One result of the difference in hardness of the two sides of the laminated products ^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 disadvantag© '

Further difficulties result from the radically different manner in which volumetric changes take place in the chromium , and carbon steels,· respectively, upon heating and cooling. These effects may on occasion adversely affect the bona between the two materials, and there is a tendency for thin sheets of the laminated materials to curl. ’ . _A . . . ,. „

It is an object of the invention to obviate the above and other. difficulties in the fabrication and use 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, filed November 2, 1932, Serial Number 640,900 filed November 2, ¹⁹³²’_c⁽_ⁿ°T.^Pa^^{at 30}1,954,344) and Serial Number 694,057, filed Octo^beOne steel’described in our said prior applications comprises about 2% to 30% chromium, carbon in 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 appliestlons comprises iron, chromium, carbon, and 45 columbium, the ranges of chromium and carbon being the same as in the case of the aboveidentified iron-chromium-carbon-titanlum steels, and the columbium content being at least about four times the carbon content and being not 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 vanadi35

2,084,278 um, In substantially the proportions: 3.5% to 20% chromium; carbon in amounts not over about 0.1%; and at least about five times the carbon content but not over 1% of vanadium* S 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 numbersobtained at several points on 5 the surface of each sheet. The Erichsen num. , bers were obtained bfi laminated sheets about 0.035 inch thick.

M

<td> Am</td><td> ilysesof</td><td> steals</td><td colspan="3"> Bockwell “B” hardness number</td><td colspan="3"> Erichsen number</td><td> 10</td>

<td> %Or</td><td> %o</td><td> %Ti</td><td> As hot rolled</td><td> Heated at 760® 0.4 hrs. and</td><td> Heated at 000° C. 10 mln. and</td><td rowspan="2"> Ashot rolled</td><td> Heated at 750° 0.4 hrs. and</td><td> Heated at 800° C. 10</td><td></td>

<td></td><td></td><td></td><td></td><td> aircooled</td><td> aircooled</td><td> air cooled</td><td> aircooled</td><td> 15</td>

<td> 5.56</td><td> 0.10</td><td></td><td> no</td><td> 79</td><td>⁰ 106</td><td></td><td rowspan="2"> 8.4</td><td></td><td></td>

<td> 4 75</td><td> 0.07 a 13</td><td> aoo</td><td> 78 86</td><td> 48-82 63</td><td> 64-68 66</td><td> 4.3</td><td> 6.0</td><td></td>

<td> 12. 50</td><td> 0.07 a 12</td><td> —</td><td> 78 108</td><td> 48-62 83</td><td> 64-68 107</td><td> a7</td><td> 0.2</td><td> 8.7</td><td></td>

<td> 13.35</td><td> 0.07 an</td><td> a 85</td><td> 78 84</td><td> 48-62 72</td><td> 64-68 70</td><td> 4.7</td><td> 0.0</td><td> 7.0</td><td> 20</td>

<td> 18.32</td><td> 0.07 a 12</td><td></td><td> 78 101</td><td> 48-62 82</td><td> 64-68 87</td><td> ao</td><td> 0.0</td><td> 8.8</td><td></td>

<td> 18.30</td><td> a 07 an</td><td> a oi</td><td> 78 88</td><td> 48-62 73</td><td> 64-68 73</td><td> 8.7</td><td> ao</td><td> . f-7</td><td></td>

<td rowspan="2"> 28.61 26.00</td><td> ao7.</td><td></td><td> 78</td><td> 48-52</td><td> 64-68</td><td> ao</td><td> ao</td><td> 8.7</td><td></td>

<td> 0.24 a 07 0.20</td><td> 1.00</td><td> 04 78 88</td><td> 84 48-52 83</td><td> 87 64-68 80</td><td> 5.6</td><td> a7</td><td> ao</td><td> 25</td>

<td></td><td> 0.07</td><td></td><td> 78</td><td> 48-52</td><td> 64-68</td><td> ao</td><td> a 8</td><td> 0.6</td><td></td>

ing a surface of a suitable piece of non-harden10 able 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 w soft metal, or a soft alloy, may be interposed between the said surfaces to aid in forming a secure bond; but such an expedient will not ordinarily be necessary.

Another method of making the article of the 40 invention is to cast the corrodible base metal against a.surface of a sheet of non-hardenable chromium alloy steel, and subsequently to hotroll or to forge the composite article.

¹¹¹ accompanying drawing,'the sole figure 45 is a cross-sectional view of a typical article embodying the invention, showing a sheet of iron or mild steel united to a sheet of non-hardenable chromium steel.

__ The chromium alloy steel of decreased harden•0 ability forming the surface portion of the lamlnated article of the invention exhibits in the asrolled state a surface hardness and thermal properties approaching those of iron and ordinary steel touch more closely than do the alr-hardenβο able 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 lamlnated sheets comprising single sheets of mild steel ^w &lt;0.07% carbon) united to single sheets of chromium steel free from titanium, columbium, and vanadium, and to single sheets of non-hardenable chromium steels, respectively. The following table includes representative data from these 70 tests. Analyses are given in each case of the metal on the chromium steel 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 45 laminated sheets 0.09 inch thick, the hardness

Similar results are obtainable by the use of the steels containing columbium and/or vanadium 30 instead of part or all of the titanium.

The method of the invention affords the advantages of simplicity and cheapness, and the articles of the invention possess none of the abovediscussed limitations and disadvantages of the 35 laminated articles heretofore known. Further, the articles of the invention possess other unique advantages: for example, they may be welded without excessive hardening, or cracking, and the chromium alloy steel win be reduced in thick- 40 ness, during hot or cold rolling, at nearly the same rate as the 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 inven- 45 tion.

The corrodible metal base may be an iron/a mfld steel, or any steel ordinarily used for structural purposes, and may contain the relatively small amounts .of alloyed additions frequently 50 added to structural steels to improve their strength.

The non-hardenable chromium alloy steel surface may for some purposes contain molybdenum and/or tungsten, say up to about 3% molybde- 55 num or up to about 5% tungsten.

Hie invention includes laminated articles of all shapes, including plates, sheets, rods, and tubes having a body of corrodible metal and one or more surfaces of corrosion resistant steel, and 60 articles cut, drawn, rolled, forged, or otherwise fabricated from such plates, sheets, rods, or tubes. Variations and equivalents of the invention herein described will readily occur to those in the art, and such variations and equivalents are 65 within the spirit of the invention.