Anodic Treatment Improves Surface Properties of Stainless Steel

Bright annealing, that is, annealing under a reducing atmosphere, is an economical method of annealing stainless steel; it has the added advantage that it prevents a chromium depleted surface such as is produced by air annealing and pickling. However, bright annealing does result in poor bright chromium platability and decreased pitting resistance. It is necessary to alter the film on bright annealed stainless steel before chromium flashing since failure to do so results in a chromium plate that has a dull gray or hazy appearance. This problem can be overcome by buffing the surface prior to chromium plating. This paper discusses a new electrolytic treatment for bright annealed stainless steel (AISI 400 series) by which the stainless steel may be plated directly with chromium without first buffing. Results of a series of experiments performed to determine the range of current density, treatment time, temperature, and pH that can be used to obtain a bright platable surface will be reported.