Importance of Electrochemical Potential Measurement in Developing Corrosion Resistant Metals and Alloys

摘要

It is a great honor for me to write this paper commemorating receipt of the Award of Japan Association of Corrosion Engineering for 2000. Several corrosion resistant metals and alloys have been developed in Corporate Research and Development Laboratories of Sumitomo Metal Industries Limited, and then Venture Business Laboratory, Hiroshima University since I began to work as researcher in 1962: sulfur dew point corrosion resistant low alloy for oil-fired boilers, seawater resistant duplex stainless steel, stress corrosion cracking resistant 316 stainless steel for boiling water reactors (BWR), nickel base thermally treated alloys 600 and 690 for pressurized water reactors (PWR), 310 Nb stainless steel, and zirconium for reprocessing plants dealing with spent nuclear fuels. It was also identified that #alpha#- (Fe_(1-x), Cr_x) OOH was the main constituent of protective rust layers formed on the weathering steel exposed to atmosphere for a quarter century.These alloys were developed in the sequence, firstly clarification of corrosion mechanism for alloys, secondly development of an accelerated corrosion testing method, thirdly alloy designing, and finally field testing for evaluation of the alloys in practical corrosive conditions. Measurements of corrosion potential were very useful in the above mentioned procedures.The author appreciate heartily to the persons concerned with the developments of these alloys which have been successfully used in various industries up to now since each of them was put into the first market use.