Platinum Metals Rev., 1988, 32, (1), 21
Palladium in Low Alloy Steels
Palladium has been examined as a possible alloying addition to various grades of iron-based alloys, particularly medium strength non-stainless ferritic steels, to decrease susceptibility to hydrogen embrittlement. Although the mechanism by which palladium alters the characteristics of these materials is still uncertain, the benefits achieved by this alloying technique have been observed recently in high strength steels, and reported by B. E. Wilde, I. Chattoraj and T. A. Mozhi of the Fontana Corrosion Centre, Ohio State University (“The Influence of Palladium on the Resistance of Low Alloy Steels to Hydrogen Embrittlement”, Scr. Metall., 1987, 21, (10), 1369–1373), their work receiving financial support from the General Motor Corporation and Sandia National Laboratory.
In the case of high strength low alloy steels, resistance to hydrogen embrittlement can be achieved with quite low levels of palladium addition and in less severe hydrogen charging environments. A particular application for such improved material is said to be for automobile spring fasteners, where failures caused by hydrogen embrittlement from corrosion in deicing salts can be a problem.
The introduction of palladium into the surface of heat treated steel by ion implantation also resulted in the elimination of hydrogen embrittlement, when 6.5 atomic per cent palladium was implanted to a depth of 11 nm below the surface. Clearly this developing technology could have major implications on the performance of other steel structures. Further studies are being undertaken to provide information on the palladium/hydrogen interaction at the atomic level.