US2222473A - Corrosion resistant nickel-base alloy - Google Patents

Description

Patented Nov. 19, 1940 PATENT OFFICE CORROSION RESISTANT NICKEL-BASE ALLOY Claude R. Bishop, Niagara Falls, N. Y., assignor to Haynes Stellite Company, a corporation of Indiana No Drawing. Original application August 24,

1939, Serial No. 291,672. Divided and this application April 12, 1940, Serial No.'329,263

5 Claims.

to solutions of hydrochloric acid. Alloys of the foregoing type are disclosed in Patents 1,514,064 and 1,753,904, issued to A. J. Mandell and C. E. Plummer, respectively. While extensive use has been made of the excellent resistance of such alloys to corrosion by hydrochloric acid, there is a demand for alloys having even greater resistance to this acid.

The principal object of this invention is to provide a nickel-base alloy havingimproved corrosion resistance, particularly to hydrochloric acid,

and good physical properties. This and other objects are attained in the present invention by the application of mydiscovery that the addition of antimony, within certain definite composition limits, greatly improves the corrosion resistance and other properties of the nickel-base alloys.

Alloys included in the invention contain silicon in a proportion between 3% and 14%, preferably between 6% and 11%; antimony in a proportion 5 between 0.02% and 10%, preferably between 0.3%

and 5%; copper in a proportion between 0.05% .and 25%, preferably between 1% and 4%; with or without aluminum in a proportion between 0.02% and 5%, preferably between 0.5% and 3%;

5 remainder nickel which may be partly replaced.

by cobalt or iron or both. In addition to the foregoing elements a small proportion of manganese may be present to improve the hot working characteristics of the alloy.

w v The following table indicates the composition of several representative alloys of the invention and also indicates the results of corrosion tests made on samples of those alloys and on samples of alloys containing no antimony but otherwise sim- I ilar to those of the invention.

Corrosion rate in milligrams per square cen- Composition (remainder Ni) gg gg $9 32 3; H0] at a temperature of 70 C.

First Second Third 3 si Cu Al Sb 4s 4 4s 7 hours hours hours Per Per Per cent cent cent 3 None None 0.76 0. 77 3 None None 0.6 0.5 0.5 3 None 0. 34 0 45 0. 33 0. 23 3.4 None ,0.5 0.44 0.27 0.22 3 None 1. 7 0.31 0. 22 0. 41 3.1 None 3.5 0.34 0.39 3. 1 None 7. 0. 23 0. 27 3.5 3.8 None 0. 48 0. 31 2. 9 3. 2 2. B 0. 24 0.-l1 13. 7 3. 7 Y 1.4 0. 38 0. 48

Not tested.

The corrosion rates shown in the above table were determined by completely immersing the specimen in the acid solution indicated therein and maintaining that solution at constant temperature for the periods of time indicated. The loss in weight was determined and reported as the number of milligrams dissolved per square centimeter of surface per hour of time.

The addition of 0.3% to 5% antimony to the alloys described herein, in accordance with the preferred procedure of the invention, does not materially afi'ect their mechanical properties, but greater proportions of antimony, that is, between 5% and usually lower the strength of the alloy somewhat. However, in either instance thealloys possess excellent corrosion resistance, and in apparatus constructed from alloys containing the greater proportions of antimony a proper allowance in the design of such apparatus may be made to compensate for the decrease in strength of the alloy.

I claim:

1'. An alloy comprising silicon in a proportion between 3% and 14%; copper in a proportion between 0.05% and 25%; antimony in a proportion, between 0.02% and 10%, serving to impart improved corrosion resistance to the alloy; the

remainder substantially all nickel.

5. An alloy comprising silicon in a, proportion between 6% and 11%; copper in a proportion between 1% and 4%; antimony in a proportion, between 0.3% and 5%, serving to impart improved corrosion resistance to the alloy; remainder nickel.

R. BISHOP.

antimony is in a proportion between 0.3% and v 5%. I