ボロン処理した Cr-Mo-Nb 鋼の強度・靱性に及ぼす Si の影響

概要

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Effect of Si content on the various mechanical properties and microstructures in B-treated Cr-Mo-Nb steels has been investigated. 1) By increasing Si content, Charpy transition temperature of shear area (_vT_<rs>) raises due to solution hardening and coarsening of austenite grain size, when coarse boro-carbides are not formed along grain boundaries during tempering treatment at high temperature. 2) Si suppresses the coarsening of intergranular boro-carbides in case of high temperature tempering. As a result, in a steel containing excess dissolved B and so having boro-carbides along grain boundaries, it is considered that Si does not change _vT_<rs> spite of solution hardening and coarsening of austenite grain size due to increase of Si content. 3) In an as quenched condition, austenite grain boundaries in a low Si content steel are clearly revealed, but those in a high Si content steel are not clearly observed after conventional etching. Consequently, it is considered that Si affects the grain boundary segregation.
社団法人日本鉄鋼協会の論文
1987-01-01