Method of forming aluminum coating layer on ferrous base alloy workpiece

A method of forming an aluminum coating layer on the surface of a workpiece of austenite stainless steel which comprises the steps of applying onto the surface of the stainless steel workpiece a coating solution containing 50 to 90% by weight of aluminum or aluminum alloy particles of 10 to 500.mu. and 10 to 50% by weight of a vinyl acetate resin having a high decomposition burning temperature with slow burning speed and being soluble in a solvent at normal temperature, with subsequent drying thereof to form a resin coating layer containing aluminum on the surface of the stainless steel workpiece, and thereafter subjecting said workpiece thus treated to heating to a temperature higher than melting point of the aluminum or aluminum alloy particles so as to form an Al plated layer on the surface of said stainless steel workpiece;

• then heating said stainless steel workpiece having the Al plated layer on the surface thereof at temperatures of 700.degree. to 850.degree. C. for more than 10 minutes to form a compound layer mainly composed of Fe-Al on the surface of said stainless steel workpiece;
• and
• heating said stainless steel workpiece having said compound layer formed on the surface thereof at temperatures of 900.degree. to 1000.degree. C. for more than 30 minutes to form an Al alloy layer mainly composed of Al and Fe on the surface of said stainless steel workpiece.