페라이트상을 갖는 마르텐사이트계 내열강의 기계적성질과 감쇠능에 미치는 시효의 영향

Abstract

This study was carried out to investigate the effect of aging on the mechanical properties and damping capacity of 12%Cr and 12%Cr-Mo martensitic heat resistant steels with ferrite phase. The result obtained from this study are as follow: The hardness change of the specimen added Mo existed two peaks with increasing of the aging time, while the hardness change in martensite phase was a low hardness value in the early stage of aging While the hardness change of the specimen not added Mo in Ferrite phase didn't change, in martensite phase dramatically decreased in the early stage of aging. While the ferrite phase of the specimen added Mo mainly precipitated Laves phase, the interface of martensite, ferrite were overlapping precipitated Laves phase and carbide. While the precipitate was not detected in the specimen of ferrite phase not added Mo, the Carbide only precipitated in martensite structure. The tensile stre - ⅱ - ngth of specimen added Mo eventually decreased with increasing of the aging time, because the disk shape of Laves phase precipitated, while the tensile strength of specimen not added Mo slowly decreased. The impact toughness of the specimen added Mo got a low value by the aging treatment, while the impact toughness of the specimen not added Mo gradually increased in the early stage of aging. While the damping capacity decreased with the increase of austenitizing temperature and time. also, the damping capacity was higher the specimen of single phase structure than the specimen of ferrite in martensite.