US1904712A - Stain resisting cobalt alloy - Google Patents

Description

Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE FREDERICK MI. BECK-ET, OF NEW YORK; N. 'Y., ASSIGNOR TO ELECTRO METALLURGICAL COMPANY, A. CORPORATION OF WEST VIRGINIA s'mm nnsrsrme 001mm ALLOY N0 Drawing.

This invention relates to stain resisting alloys containing as essential constitutents the metals iron, chromium, manganese and cobalt.

In application serial No. 435,957 filed by me on March 14, 1930, I have disclosed stain resisting ferrous alloys containing not less than about sixteen per cent nor more than about twenty-two per cent of chromium, and not less than about six per cent nor more than about sixteen per cent of manganese. I have shown that when these alloys contain not more than about three tenths per cent carbon and preferably not more than twelve hundredths .per cent of this element, they possess excellent workabllity and \are adapted to deep drawing operations. In applicationv Serial No. 448,428 filed simultaneously herewith I have shown that the iron-chromium-manganese compositions are more resistant than the workable stainresisting iron-chromium-nickel alloys to attack, by gasses containing sulphur com.- pounds and I have also shown that an addition of cobalt to the iron-chromium-manganesebase will markedly increase its strength at elevated temperatures ,without destroying its working properties or its resistance to sulphur-bearing gases and other corrosive influences. The invention claimed herein is the. group of alloys produced by so combining iron, chromium, manganese and cobalt.

The high temperature strength is in-. creased by cobalt percentages as-low as one per cent and perhaps even lower. With higher percentages of cobalt the efl'ect is more pronounced but as the cobalt rises above about five per cent the high temperature strength is not additionally greatly in creased. Cobalt percentages between the approximate limits of one per cent and ten per cent are regarded as the most useful.

The following examples show the efiect Application filed April 29,

1030. Serial n0. 448,420.

of cobalt on the strength of the chromeiron-manganese alloys at 900 C.

Percent Percent Percent Percent Percent Percent in. max. red. of 1' Mn 0 C0 8m 01. n 2' area 11.17 1 r 8. 09 0. 00 e. 250 4.1 00. 17. 19 10. 27 0. 11 9, 000 43 72. g 17. 30 8. 60 0. 09 2. 14. 500 44 72. 80 18. 8. 80 0. 12 4. 97 19, 120 36 73. 17. 36 8. 76 0. 14 8. 85 18, 250 45 65. 40 17. 56 8. 74 0.15 13. 95 21, 400 25 65. 10

In the tests tabulated above th'e test pieces were held at 900 C. for about forty minutes before applying the load and the load was applied gradually and at a uniformly mcreasing rate so that about twenty minutes was required torupture the test piece.

The following examples show the efl'ect of cobalt on. the strength of the chromeiron-manganese allows at 600 C.

. Lbs./sq.ln.

Per- Pe f- Per- Po a? cent cent cent can? Mn o 00 mm Max. 51.1112" point stress m 11.10 10.21 0. 1 20,000 30,150 41 vis per cent carbon have a distinct field of utiland carbon, the carbon content being ity. ,Where the alloy is to be subjected to not more than about 0.12%;the remainder deep drawing or like severe cold working being chiefly iron.

- operation it is often advantageous to cool it 3 in air or quench it from temperatures in the vicinity of 1000 C. to 1150" C.

A principal field of application for the herein described alloys is in the thermal decomposition of hydrocarbon material, for example the cracking of petroleum fractions to produce gasoline. Such decompositions are ordinarily carried out in tubes and the latter may be subjected at a high temperature to oxidizing conditions on the outside and simultaneously to the action of sulfur compounds associated with the material being cracked and contained within the tubes. The alloys of the invention are in all respects admirably adapted'to the fabrication oftubes for such operations, and they are equally suitable for makin thetubular condensers in which the crac ed products are usually liquefied.

- I claim:

1. A ferrous alloy containing chromium not less than about sixteen percent nor more than about twenty-two per cent, manganese not less than about six per cent nor more than about sixteen per cent and cobalt not less than about one per cent nor more than about ten per cent, and carbon, the carbon content being, not more than three tenths of one per cent; the remainder being chiefl iron.

2. A stain resisting ferrous alloy aving deep drawing properties and containing" chromium about elghteen percent, manganese about ei ht per cent, carbon, the content of carbon ieing, not more than twelve hundredths per cent and about five per cent of cobalt; the remainder being-chiefly iron.

3. An article of manufacture sub ect to the action of hot sulfur-bearin gases, said article being composed of a errous alloy containing chromium not less than about 16% and not more than about 22%, manganese not less than about 6% and not more than about 16%, cobalt not less than 1% and not more than aboutl0%, and carbon, the carbon content being not more than about 0.3%; the remainder being chiefly iron.

4. An oil cracking tube composed of a ferrous alloy containing chronium not less than about 16% and not more than about 22%, manganese not less than about 6% and not more than about 16%, cobalt not less than about 1% and not more than about 10%, and carbon, the carbon content being not more than about 0.3%.; the remainder a being chiefly iron. 5, An oil cracking tube composed of a ferrous alloy containing chromium not less than about 16% and not more than about 22%, manganese not less than about 6% and not more than about 16%, cobalt not less '65 than about 1% and not'more than about In testimon whereof, I aflix my signature.

F EDERICK M. BECKET.