21Cr-12Ni オーステナイト耐熱鋼のクリープ破断特性への C および P 添加の影響

概要

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The creep rupture properties of 21Cr-12Ni austenitic heat resisting steels containing various content of carbon and phosphorus have been investigated on the basis of grain- and grain boundary-strengths. The addition of phosphorus promotes the homogeneous precipitation of M_<23>C_6 carbides inside grains an deceases the minimum creep rate. The strength of grains evaluated by the minimum creep rate depends mainly upon the phosphorus content. On the contrary, the strength of grain boundaries evaluated by the grain boundary configuration depends mainly upon the carbon content. The rupture strength of steels having straight boundaries is improved with the increase in phosphorus content owing to the increase in the strength of grains. The phosphorus addition above about 0.25%, however, is not effective to improve the rupture strength because of the poor grain boundary strength of these steels. On the other hand, in the steels having stronger zigzag boundaries, the higher the phosphorus content, the higher the rupture strength. Moreover, the rupture strength of the latter is always higher than that of the former regardless of phosphorus content. It is emphasized that the optimum content of carbon and phosphorus should be considered from a point of view of the harmony of grain- and grain boundary-strengths.
社団法人日本鉄鋼協会の論文
1980-03-01