QLT热处理对油套管用钢显微组织与力学性能的影响  

Effect of QLT heat treatment on microstructure and mechanical properties of oil casing steel

作　　者：刘文月 李天怡 安涛 李江文 杨博威 解德刚 Liu Wenyue;Li Tianyi;An Tao;Li Jiangwen;Yang Bowei;Xie Degang(State Key Laboratory of Metal Materials for Marine Equipment and Application,Anshan Liaoning 114009,China;Ansteel Beijing Research Institute Co.,Ltd.,Beijing 102209,China;Angang Steel Group Co.,Ltd.,Anshan Liaoning 114009,China)

机构地区：[1]海洋装备用金属材料及其应用国家重点实验室,辽宁鞍山114009 [2]鞍钢集团北京研究院有限公司,北京102209 [3]鞍钢股份有限公司,辽宁鞍山114009

出　　处：《金属热处理》2025年第1期103-109,共7页Heat Treatment of Metals

摘　　要：研究了一种高强油套管用钢在热轧态、860℃淬火态以及860℃淬火+800℃两相区淬火+200、660℃回火(QLT)处理后的显微组织和力学性能,并利用EBSD和TEM深入研究了高温和低温QLT处理后的微观组织特征与力学性能的关系。结果表明:热轧态试验钢的微观组织为粒状贝氏体+珠光体+少量多边形铁素体;经860℃淬火后,组织为板条马氏体以及少量贝氏体;经低温QLT处理后,组织转变为回火马氏体和铁素体,屈服强度为936 MPa,抗拉强度为1260 MPa,屈强比为0.74,0℃冲击吸收能量为40 J,此时试验钢中小角度晶界占34.9%,位错密度为10.2×10^(14) m^(-2),等效晶粒尺寸为1.43μm;经高温QLT处理后,组织转变为回火索氏体和铁素体,应力-应变曲线出现屈服平台,屈服强度为833 MPa,抗拉强度为912 MPa,屈强比高达0.91,0℃冲击吸收能量提高至93 J,具有最佳的强韧性匹配,此时试验钢中小角度晶界占比降低至30.9%,位错密度减小至9.6×10^(14) m^(-2),等效晶粒尺寸减小至1.39μm,这使得试验钢的强度下降,同时塑性有所上升。Microstructure and mechanical properties of a high strength oil casing steel under different heat treatment conditions as hot rolling,quenching at 860 ℃,and quenching at 860 ℃+quenching at two phase region of 800 ℃+tempering at 200 ℃ and 660 ℃(QTL),respectively,were analyzed,and the relationship between microstructure and mechanical properties of the steel after low temperature QLT and high temperature QLT treatment was studied by means of EBSD and TEM.The results show that the microstructure of the hot-rolled steel is granular bainite+pearlite+a small amount of polygonal ferrite.After quenching at 860 ℃,the microstructure consists of lath martensite and a small amount of bainite.After low temperature QLT treatment,the microstructure transforms into tempered martensite and ferrite,the yield strength is 936 MPa,the tensile strength is 1260 MPa,the yield ratio is 0.74,and the impact absorbed energy at 0 ℃ is 40 J,meanwhile,the proportion of LAGB is 34.9%,the dislocation tensity of GND is 10.2×10^(14) m^(-2),and the equivalent grain size is 1.43 μm.After high temperature QLT treatment,the microstructure transforms into tempered sorbite and ferrite,yield plateau appears in the stress-strain curve,the yield strength is 833 MPa,the tensile strength is 912 MPa,the yield ratio is 0.91,the impact absorbed energy at 0 ℃ increases to 93 J,all of which show best strength and toughness matching,however,the proportion of LAGB decreases to 30.9%,the dislocation density of GND decreases to 9.6×10^(14) m^(-2),the equivalent grain size decreases to 1.39 μm,which makes the strength of the tested steel decrease and the plasticity increase.

关 键 词：油套管用钢 QLT工艺 EBSD分析 强韧性匹配 

分 类 号：TG441.8[金属学及工艺—焊接]