热输入对440 MPa级HSLA钢埋弧焊对接接头组织及性能的影响  

Effect of Heat Input on the Organization and Properties of Submerged arc Welded-joints for 440 MPa Grade HSLA Steel

作　　者：代海洋 贺建芸[1] 付俊杰[1] 杜立强 魏靖柠 左月 安同邦[2] DAI Haiyang;HE Jianyun;FU Junjie;DU Liqiang;WEI Jingning;ZUO Yue;AN Tongbang(School of Mechanical and Electrical Engineering,Beijing University of Chemical Technology,Beijing 100029,China;Welding Research Institute of Iron and Steel Research Institute,Beijing 100081,China)

机构地区：[1]北京化工大学机电工程学院,北京100029 [2]钢铁研究总院焊接研究所,北京100081

出　　处：《电焊机》2024年第5期52-59,共8页Electric Welding Machine

基　　金：国家重点研发计划项目(2017YFB0304804)。

摘　　要：采用20 kJ/cm,25 kJ/cm,30 kJ/cm三种焊接热输入进行440 MPa级HSLA钢埋弧焊试验,使用光学显微镜、扫描电子显微镜、透射电子显微镜、维氏硬度仪以及冲击试验机等实验仪器,研究了焊接热输入对接头显微组织和力学性能的影响。结果表明,三种不同的热输入下的焊缝金属的显微组织主要由先共析铁素体、侧板条铁素体、针状铁素体以及少量残余奥氏体组成,粗晶热影响区的显微组织主要由粒状贝氏体组成。随着焊接热输入的增加,焊缝金属中针状铁素体的含量不断降低,先共析铁素体和侧板条铁素体的含量逐渐升高;粗晶热影响区中粒状贝氏体的晶粒尺寸明显增大,焊缝金属中直径大于1μm的夹杂物占比从40.7%逐渐升高至59.9%,因此使得焊缝金属的强度和低温冲击韧性下降。当热输入为20 kJ/cm时,焊缝金属的平均硬度值最高,且低温冲击韧性达到最优;当热输入从20 kJ/cm开始增大时,焊缝冲击功从186 J下降至130 J,冲击断口中韧窝尺寸逐渐减小,深度变浅,断口形貌由韧性断裂向准解理断裂过渡,降低了裂纹扩展所需的能量,使得冲击吸收功不断减小。The submerged arc welding test of 440 MPa HSLA steel was carried out with three welding heat inputs of 20 kJ/cm,25 kJ/cm and 30 kJ/cm,and the effects of welding heat input on the microstructure and mechanical properties of the welded joints were studied by optical microscope,a scanning electron microscope and so on.It was shown that under three different heat inputs,the microstructure of weld metal was mainly composed of pre-eutectic ferrite,side lath ferrite,acicular ferrite and a small amount of residual austenite,and the microstructure of the coarse-crystalline heat-affected zone was mainly composed of granular bainite.With the increase of welding heat input,the content of acicular ferrite in the weld metal decreased,the first eutectic ferrite and side lath ferrite content in the gradual increase in the grain size of the coarse grain heat-affected zone in the granular bainite increased significantly,the weld metal with a diameter greater than 1μm of inclusions in the ratio of the weld metal gradually increased from 40.7%to 59.9%,so that the strength of the weld metal and the impact toughness of the low-temperature decline;When the heat input was 20 kJ/cm,the average hardness value of the weld metal was the highest,and the low-temperature impact toughness reaches the optimum;when the heat input increased from 20 kJ/cm,the weld impact work decreased from 186 J to 130 J,the size of the ligamentous fossa in the impact fracture decreased gradually,and the depth gradually became more and more shallow,and the fracture morphology was transitioned to the quasi-dissolutional fracture by the ductile fracture,which lowered the energy required for the crack expansion,and made the impact of absorptive work decreasing.

关 键 词：HSLA钢 埋弧焊 热输入 针状铁素体 冲击韧性 

分 类 号：TG457.1[金属学及工艺—焊接]