METHOD OF PRODUCING A CORROSION RESISTANT LAYER ON LOW-ALLOY STEEL PRODUCTS

摘要

A non-alloy steel component is nitrocarburized at 550° to 720. degree. C. for up to 4 hours in a nitriding gaseous atmosphere eg. ammonia or ammonia and endothermic or exothermic gas, and is thus exposed to air or other oxidizing atmosphere for 2 to 120 seconds to form an oxide-rich layer thereon before being quenched into an oil/water emulsion, degreased and a tack-free wax coating applied. Alternatively, the component may be cooled in air or other oxidizing atmosphere and then wax coated or it may be cooled in a non-oxidizing atmosphere and then reheated to provide the oxide-rich surface layer before being cooled again and wax coated. As a further alternative, the component may be cooled, lapped to a surface roughness of not more than 0.2 micrometers Ra, reheated to oxidize and then quenched. These techniques give a good corrosion resistance to the component.