US2145020A - Nickel-chromium alloys - Google Patents

Description

Patented Jan. 24,- 1939 2,145,020 NIOKEL-CHROMIUM ALLOYS Frederick M. Becket, New York, and Russell Franks, Niagara Falls, N. Y., .assignors-to Electro Metallurgical Company, a corporation of West Virginia No Drawing. Application June 15, 1938, Serial N0. 213,816

This invention concerns nickel-chromium al- TABLE I loys. Such alloys have been used for a long time and have served well in resisting corrosion Composition (remainder Fe) and deterioration at high temperatures. They M t N f 5 are suitable for heating elements because of their a 3:; 5g; 5g; 5:; 5g; Egg Big? high electrical resistivity and their excellent re- Cr Ni Mn c Cb sistance to oxidation. As a rule, the alloys contain atleast 60% nickel and or more chro- 12.9 77.4 2. 05 0.20 0.06 None 74 10 mium. In some instances, iron has been presis} 3 g; 8 3; 53 ent in a percentage as high as while in 12.2 74.4 1.95 0.29 0.06 2.02 othiers it has been held to a much lower per- Q3 it; 3122 3 3?; 33 cen age.

The forging of ingots of such alloys is often Tensile tests on metal, as hot rolled, thousands l5 diflicult. By careful control of the melting pracof pounds per square inch tice, and by the use of appropriate deoxidizers,

the forgeability of the alloy ingots can be im- Yield Tensile Percent, Percent proved to a considerable degree, but even under point Strength g u rgz g gc tgg the most carefully controlled conditions some difilculty is encountered from tearing, check- 1 58 0 76 5 9 31 ing, and cracking of the ingot during the hot 1 6610 106:7 a4 57 working operations. To obtain a product of high 23 quality it is necessary to grind the partially 57:0 96:0 16 23 25 forged ingot frequently to remove such defects. 103'0 20 26 We have found that improved hot working properties can be imparted to the nickel-chro- Tliese lmproYements are i mium alloys by the addition of columbium in i g rgslstanci to g g g relatively small proportions, for example about 21 ag 2 2g; ggfi fg gf i 30 some improvement Occurs when proximately the same low rate of oxidation, when lumblum i is as as and 1t is heated in air at 1050" to 115m 0., to alloys made unnecessary to add more than 2% columbium under the same conditions but containing no We o ot d fi i e y w y columbium columbium. This is demonstrated by data of proves the hot working properties of the alloys, T m II. although it has been observed that the alloy TABLE II ingots treated with columbium do not pipe to as great an extent as those that contain no Composition rest Fe) Percentlossm columbium, even though the alloys have been weightofsamotherwise melted and deoxidizedin the same MmlN Per- Per- Per- Per- Per- Peri ggi jmanner. The columbium addition produces a a fig *5? 6 8? air definite refinement in grain size, which undoubtedly influences the hot working properties of the M7 M5 None 51 metal. As shown in the accompanying Table 45 No. I, the alloys treated with columbium possess 31 23 81% i: i

a higher degree of ductility and toughness in the hot-rolled condition, which means that, in- Accordingly the invention comprises a nickelherently, the alloys treated with columbium chromium alloy containing 10% .t 30% would have less tendency to tear or check when mium, 0.2% to' 2% columbium, iron in an amount deformed either hot or cold.

not exceeding 15%, the remainder nickel which may include incidental impurities and iresidual deoxidizers. Preferably, the chromium content is between 15% and 25% and the iron content is less than 5%.

The nickel-chromium alloys of the invention may be deoxidized, before the addition of the columbium, with manganese or silicon, or with other deoxidizers such as calcium, aluminum, zirconium, or titanium. Residual deoxidizer other than silicon and manganese should not exceed about 1%; manganese is preferably less than 3% and the silicon is preferably less than 1%. The low percentages of phosphorus and sulphur and other incidental impurities usually present in commercial alloys 01' this type may also be present in the metal of the invention.

We claim;

1. Alloy having substantially the composition: 10% to 30% chromium, 0.2% to 2% columblum, iron in an amount not exceeding 15%, the remainder nickel.

2. Alloy resistant to oxidation and deterioration at high temperatures and composed substantially of 15% to 30% chromium, 0.2% to 2% columbium, iron in an amount less than 5%, the remainder nickel.

FREDERICK M. BECKE'IT. RUSSELL F'RANKS.