Microstructure-property relationship of a high strength-toughness Cr-Mo-V steel  

作　　者：Ce Liang Guangxin Song Liguang Liang Wanlin Wang Hang He Jie Zeng 

机构地区：[1]School of Metallurgy and Environment,Central South University,Changsha 410083,China [2]National Center for International Research of Clean Metallurgy,Central South University,Changsha 410083,China [3]Hunan Hengyang Steel Tube Group,Hengyang 421000,China

出　　处：《International Journal of Minerals,Metallurgy and Materials》2025年第5期1128-1140,共13页矿物冶金与材料学报(英文版)

基　　金：supported from the National Nat-ural Science Foundation of China(Nos.52274342 and 52130408);the Fundamental Research Funds for the Central Universities of Central South University,China(No.1053320213826).

摘　　要：The demand for oil casing steel with ultra-high strength and excellent impact toughness for safe application in ultra-deep wells is pressing.In improving the combination of strength,ductility,and impact toughness,the designed Cr-Mo-V micro-alloyed oil casing steel was quenched at 800,900,and 1000℃,followed by tempering at 600,680,and 760℃,respectively,to obtain distinct microstruc-tures.The results showed that the microstructure of the samples quenched at 800℃ followed by tempering comprised untransformed fer-rite and large undissolved carbides,which considerably deteriorated tensile strength and impact toughness.For other conditions,the nuc-leated carbides and the boundaries are key factors that balance the tensile strength from 1226 to 971 MPa and the impact toughness from 65 to 236 J.From the perspective of carbide,optimal precipitation strengthening is achieved with a smaller carbide size obtained by a low tempering temperature of 600℃,while larger-sized carbides would remarkably soften the matrix to improve the toughness but deteriorate the tensile strength.Additionally,an increase in prior austenite grain size with the corresponding enlarged sub-boundaries obtained by high quenching temperatures substantially diminishes grain refinement strengthening,dislocation strengthening,and the energy absorbed in the crack propagation process,which is unfavorable to strength and toughness.

关 键 词：oil casing steel quenching temperature tempering temperature carbides strength and toughness 

分 类 号：TG142.1[一般工业技术—材料科学与工程]