低活性F/M钢形变退火过程中的组织演化

Study on Microstructure Evolution of Deformed Low-Activation F/M Steel During Annealing

作为超临界水堆燃料包壳管用候选材料,设计和制备了一种高Cr低活性铁素体/马氏体钢(0.14C-11.06Cr-2.3W),实验钢经淬火回火热处理后为回火马氏体组织。对实验钢进行60%冷变形,并随后在750～820℃下退火10～720min。通过显微组织观察和硬度测量,研究了变形前后板条马氏体在回复、再结晶、奥氏体化中的组织演化规律。结果表明,预变形既影响板条马氏体的再结晶行为,又影响奥氏体化行为。无变形的板条马氏体退火时难以发生再结晶,奥氏体直接在回火马氏体的原奥氏体晶界生成;60%预变形后易发生再结晶,奥氏体在完全再结晶的铁素体晶界上形核长大。

A new kind of high-chromium low-activation ferritic/martensitic steel （0.14C-11.06Cr-2.3W）as one of the most promising candidates for SCWR fuel cladding tube was designed and fabricated.The experimental steel after quenching-and-tempering heat treatment had a typical tempered martensitic structure.The specimens were cold-deformed by uniaxial compression to a reduction of 60%and then annealed at 750-820℃ for 10-720min.The changes of matrix structure in prior cold-deformed lath martensite and softening behavior occured during annealing were investigated.The results show that the behaviors of recrystallization and austenite formation are changed by the prior deformation.The specimens without pre-deformation do not undergo recrystallization even when annealed at a rather high temperature.However,after receiving sufficiently large cold strains（60%）,the deformed lath martensite easily recrystallizes.The aus-tenite forms directly from the tempered lath martensite in the non-deformed lath mar-tensite,when the lath martensite deforms to a reduction of 60%,the recrystallization occurs prior to austenite formation,the austenite nucleates and grows at the boundaries of completely recrystallized ferrite grains.