摘要
为进一步探索改善X120管线钢的韧塑性,用X120工业连铸坯在实验室采用TMCP和TMCP后立即感应加热至500和550℃回火工艺进行模拟轧制试验,并检测其力学性能,采用扫描电镜、透射电镜分析了不同工艺下钢的组织及析出物形貌、尺寸及分布,用X射线衍射方法分析了残留奥氏体。结果表明:X120钢组织为下贝氏体、少量针状铁素体以及微量MA。感应加热回火后,板条贝氏体和针状铁素体粗化,小尺寸析出物数量明显增加。这种回火使X120钢韧塑性改善,伸长率达到17.24%,-60℃下冲击功达到232.7 J;不利的是,钢的屈服强度提高和抗拉强度下降导致屈强比更高。性能变化是回火后贝氏体组织粗化、α-Fe基体上大量析出细小弥散碳氮化铌以及残留奥氏体体积分数的变化引起的.
For further improving toughness and plasticity of X120 pipeline steel,simulated rolling experiment was carried out by TMCP and TMCP combined subsequent induction heating tempering at 500 and 550 ℃,respectively.Mechanical properties of the treated samples were tested.Microstructure and precipitates shape,size and distribution of the steel were analysed by SEM and TEM.The retained austenite was detected by XRD.The results show that the microstructure of X120 pipeline steel consists of lower bainite,a small quantity of acicular ferrite and trace retained austenite.The lath lower bainite and acicular ferrite is coarsened and the amount of small size precipitates increase remarkably in the steel after induction heating tempering.The induction temper process improves toughness and plasticity of the X120 steel,with elongation to 17.24% and impact toughness to 232.2 J at-60 ℃.The unfavourable effect is the higher yield ratio of the tempered steel due to the increase of yield strength and the decrease of tensile strength.The mechanical properties variation are caused by lower bainite coarsening,fine and disperse niobium carbonitride precipitation on α-Fe matrix and the change of volume fraction of retained austenite.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2012年第2期56-61,共6页
Transactions of Materials and Heat Treatment
基金
国家"十一五"科技支撑计划资助项目(2006BAE03A06)
关键词
X120管线钢
快速加热回火
组织
析出
力学性能
X120 pipeline steel
rapid heating temper
microstructure
precipitation
mechanical property
