Microsegregation in a F82H plate

F82H鋼板のマイクロ偏析

酒瀬川 英雄   ; 谷川 博康

Sakasegawa, Hideo; Tanigawa, Hiroyasu

BA活動を通じESR技術を用いて製造された低放射化フェライト鋼F82H-BA07ヒート鋼に対してEPMA観察を行ったところ、少なくともクロム,タングステン,バナジウム,マンガンのマイクロ偏析が圧延方向に平行に確認された。とりわけ、タングステンのは最大1.0wt%もの濃度差を生じていた。このようなマイクロ偏析は微細組織に影響を与え強度特性にも影響を及ぼすことが考えられる。そのため均質化熱処理条件の最適化は重要となる。本発表はこのマイクロ偏析がナノメートルオーダーの微細組織と強度特性に及ぼす影響を考慮しつつ、マイクロ偏析を解消できる均質化熱処理の策定を試みた。

Through the Broader Approach (BA) activity in Japan, F82H-BA07 heat of 5 tons prepared applying electrosrag remelting (ESR) has been studied as a step toward a larger-scale melting about 20 tons. From the result of elemental mapping images using electron probe microanalysis (EPMA), micro-segregation of at least four metallic elements such as chromium, tungsten, vanadium and manganese was found as stripes parallel to the hot rolling direction. In the case of tungsten segregation, the maximum difference of content was about 1.0 wt% between the observed stripes. This difference could cause differences in nano-metric structures between stripes, and affect mechanical properties. In this presentation, we discuss how much micro-segregation should be decreased considering effects of micro-segregation on nano-metric structures and mechanical properties in addition to the result of optimization of homogenizing condition.