Disclosed is a chromium-nickel stainless steel alloy article having an
adherent, wear resistant coating of metallic oxides and a method of
forming an adherent, wear resistant coating of metallic oxides on a
chromium-nickel stainless steel alloy article. The coating desirably has
a thickness of from about 25.4 to about 102 microns (1 mil to about 4
mils) and is formed by exposure of the article to an oxidizing
atmosphere, preferably air, preferably during heat treatment of the
article. Such articles are useful, inter alia, as torque drive inserts
for a friction disk for a multi-disk brake or clutch assembly. The drive
inserts can be formed of an alloy such as 17-4PH stainless steel alloy
having an adherent coating of lubricious oxides formed during frictional
contact. It is believed that these lubricious oxides will form also if
the heat treated base alloy is subject to temperatures greater than
815.6.degree. C. (1500.degree. F.) for a sufficient time in an oxidizing
atmosphere.