Evolution and Coarsening of Carbides in 2.25Cr-1Mo Steel Weld Metal During High Temperature Tempering  

作　　者：TAO Peng ZHANG Chi YANG Zhi-gang Takeda Hiroyuki 

机构地区：[1]Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China [2]Materials Research Laboratory, Kobe Steel Ltd, Hyogo 651-2271, Japan

出　　处：《Journal of Iron and Steel Research International》2010年第5期74-78,共5页

基　　金：Financial support from Kobe Steel is gratefully acknowledged

摘　　要：Transformation and coarsening of carbides in 2.25Cr-lMo steel weld metal during tempering at 700 ℃ for different time intervals ranging from 1 to 150 h were examined by transmission electron microscopy and scanning electron microscopy. M3C carbides were observed in the as-welded specimens and when tempered, the precipitates were mainly composed of M3C, M7C3, and M23C6 carbides. A sequence for corresponding carbide transformation during tempering with initial precipitation of M3 C and the subsequent precipitation of M7 C3 and M23 C6 was proposed. The precipitation of M7C3 with higher chromium content was the main factor contributing to the decrease in coarsening rate of precipitates after prolonged tempering. The decrease in hardness of the tempered specimens agreed well with the prediction of the weakening of precipitation strengthening owing to the coarsening of carbides.Transformation and coarsening of carbides in 2.25Cr-lMo steel weld metal during tempering at 700 ℃ for different time intervals ranging from 1 to 150 h were examined by transmission electron microscopy and scanning electron microscopy. M3C carbides were observed in the as-welded specimens and when tempered, the precipitates were mainly composed of M3C, M7C3, and M23C6 carbides. A sequence for corresponding carbide transformation during tempering with initial precipitation of M3 C and the subsequent precipitation of M7 C3 and M23 C6 was proposed. The precipitation of M7C3 with higher chromium content was the main factor contributing to the decrease in coarsening rate of precipitates after prolonged tempering. The decrease in hardness of the tempered specimens agreed well with the prediction of the weakening of precipitation strengthening owing to the coarsening of carbides.

关 键 词：weld metal CARBIDE TEMPERING COARSENING 

分 类 号：TG142.73[一般工业技术—材料科学与工程] TG457.11[金属学及工艺—金属材料]