COMPARISON OF THE CORROSION-RESISTANCE OF DIFFERENT STEEL GRADES NITRIDED, COATED AND DUPLEX TREATED

Duplex treatments consisting of plasma nitriding and ion plating with titanium nitride were investigated for five different steel grades: a construction steel, a hot working steel and a ledeburitic cold working steel and two martensitic stainless steels. Nitriding was performed w ith the new process. The corrosion behaviour between the bare steel, t he nitrided steel. the coated steel and the duplex treated steel was i nvestigated by cyclic polarization scan in sodium chloride solution an d by subjecting coupons to salt spray. Duplex treatments improve the c orrosion resistance of construction and hot working steel impressively when compared with nitriding or PVD coating. For the cold working and the stainless steel, duplex treatments lead to a loss in corrosion re sistance.