Microstructure Evolution in 9Cr Martensitic Steel During Long-Term Creep at 650℃  

作　　者：HU Zheng-fei WANG Qi-jiang ZHANG Bin 

机构地区：[1]School of Material Science and Engineering, Tongji University, Shanghai 200092, China [2]Institute of Baosteel, Shanghai 201900, China

出　　处：《Journal of Iron and Steel Research International》2012年第7期55-59,共5页

基　　金：Item Sponsored by National Natural Science Foundation of China(50871076)

摘　　要：Standardarized creep and rupture strength tests were conducted for commercial T91 martensitic heat-resistant steel at 650℃and corresponding microstructure was characterized by BSED, TEM and EDS. The martensitic microstructure degenerated seriously during creep exposure, including martensitic substructure recovering, carbides coarsening, dissolving and precipitating. EDS analysis shows that the M23C6 carbides in different morphologies have dissimilar compositions. The rod/sheet like M23 C6 particles within the matrix contain more additions, which might precipitate in situ while fine MX particles were re-solving. The high content of silicon in these rod/sheet like M2aC6 carbides is probably related to self diffusion coefficient increasing for the exposed condition at 650 ~C close to Curie temperature To. For those reasons, martensite substructure becomes unstable, and microstructure evolution is accelerated and leads to creep strength deteriorating severely.Standardarized creep and rupture strength tests were conducted for commercial T91 martensitic heat-resistant steel at 650℃and corresponding microstructure was characterized by BSED, TEM and EDS. The martensitic microstructure degenerated seriously during creep exposure, including martensitic substructure recovering, carbides coarsening, dissolving and precipitating. EDS analysis shows that the M23C6 carbides in different morphologies have dissimilar compositions. The rod/sheet like M23 C6 particles within the matrix contain more additions, which might precipitate in situ while fine MX particles were re-solving. The high content of silicon in these rod/sheet like M2aC6 carbides is probably related to self diffusion coefficient increasing for the exposed condition at 650 ~C close to Curie temperature To. For those reasons, martensite substructure becomes unstable, and microstructure evolution is accelerated and leads to creep strength deteriorating severely.

关 键 词：T91 steel creep strength microstructure CARBIDE COARSENING SELF-DIFFUSION 

分 类 号：TG146.23[一般工业技术—材料科学与工程] TG146.21[金属学及工艺—金属材料]