耐热合金钢P91热变形过程静态及亚动态再结晶行为  

Static and Metadynamic Recrystallization Behaviors of Heat-resistant P91 Alloy during Hot Deformation

作　　者：贾璐[1,2] 李永堂[1,2] 李振晓 

机构地区：[1]太原科技大学材料科学与工程学院,太原030024 [2]太原科技大学金属材料成性理论与技术山西省重点实验室,太原030024

出　　处：《机械工程学报》2017年第8期58-67,共10页Journal of Mechanical Engineering

基　　金：山西省回国留学人员科研(2015-086);国家自然科学基金(51135007,51675361)资助项目

摘　　要：利用单道次、双道次热压缩试验研究铸态P91合金钢在热变形后的动态、静态、亚动态再结晶行为,探索不同变形温度、应变速率、变形量对静态、亚动态再结晶的影响并建立静态、亚动态再结晶动力学方程。研究得出:热变形结束后,静态再结晶率随变形温度、变形量及应变速率的增大而增大;亚动态再结晶率与变形温度、变形量和应变速率呈单调递增,并最终趋于稳定。以真应变为参数,铸态P91热变形后再结晶类型可按照真应变分为三种情况:当ε<ε_c时,道次间隔主要发生静态再结晶;当ε_c<ε<ε_T时,同时发生静态、亚动态再结晶;当ε>ε_T时,主要发生亚动态再结晶。通过对双道次压缩试样的显微组织分析得出:相同变形条件下,亚动态再结晶晶粒比静态再结晶细小,再结晶晶粒随变形温度增加而增大,随应变速率增大而减小。Dynamic, static and metadynamic recrystaUization of as-cast P91 alloy steel are investigated through single and double-hit unidirectional thermal compression experiments under different deformation temperatures, strain rates and deformation degrees. The kinetics of static and metadynamic recrystallization are established and the results show that, the static recrystallization fraction is increasing with the increase of deformation temperature, strain rate and deformation degree; the metadynamic recrystallization fraction has the monotone increasing relationship with deformation temperature, strain rate and deformation degree. The softening methods of the deformed as-cast P91 alloy can be divided into three conditions through the values of true strain： when e〈ec, the static recrystallization operates as the prime softening mechanism in the inter-pass time; when ec〈e〈er, both static and metadynamic recrystallization are involved in the softening; when e〉er, the metadynamic recrystallization is the predominante softening mechanism. In addition, the microstructure of the specimens are observed, it can be found that the grain sizes of MDRX are smaller than SRX in the same deformation conditions, the grain sizes of recrystallization are increasing with the increase of deformation temperature and decrease with the increase of strain rate.

关 键 词：耐热合金钢 热变形 静态再结晶 亚动态再结晶 真应变 大口径厚壁管 

分 类 号：TG335[金属学及工艺—金属压力加工]