Cr 系フェライトステンレス鋼の耐高温酸化性と高温酸化機構

概要

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The relation between the effects of C, N, Cr and Si contents on the oxidation resistance and the metallurgical structure of 11∿17%Cr steels has been studied at temperatures lower than 1000℃. C and N have very harmful effects, and Cr and Si have very beneficial effects. It has been found, however, that their effects depend on the austenitic phase precipitates at the oxidation temperature, that is, the appearance of the austenitic phase has harmful effect against the oxidation resistance. It is suggested that decreasing C and N contents or adding stabilized elements such as Zr, Ti and Nb is effective against the oxidation resistance. Among the stabilized elements, Zr is beneficial, but Ti and Nb are not very effective. Difference of their behaviors depends on the stability of their carbides and nitrides at 1000℃. Because Zr compound does not decompose at 1000℃, the austenitic phase does not precipitate, whereas Ti or Nb compound decomposes at 1000℃ and the austenitic phase precipitates in Ti- or Nb-containing steel. The steel containing high C and the steel containing Nb or Ti have austenitic phases mainly around the grain boundaries at 1000℃. It has been found that the unusual oxidation phenomenon occurs from the precipitation sites of austenitic phase, of which Cr content is less than that of ferritic phase that is determined by means of optical microscope, EPMA, IMMA and so on.
社団法人日本鉄鋼協会の論文
1983-04-01