热输入对800 MPa级HSLA钢焊接接头组织及性能的影响  

Effect of Heat Input on Microstructure and Mechanical Properties of 800 MPa Grade HSLA Steel Welded Joints

作　　者：孟满丁 魏金山[1] 安同邦[1] 马成勇[1] 左月 MENG Manding;WEI Jinshan;AN Tongbang;MA Chengyong;ZUO Yue(Welding Institute,Central Iron&Steel Research Institute,Beijing 100081,China)

机构地区：[1]钢铁研究总院焊接研究所,北京100081

出　　处：《热加工工艺》2023年第23期35-39,49,共6页Hot Working Technology

摘　　要：采用光学显微镜(OM)、扫描电子显微镜(SEM)、电子背散射衍射(EBSD)、拉伸和冲击等试验方法,研究不同热输入(14~20 kJ/cm)对18 mm厚800 MPa级低合金高强(HSLA)钢熔化极气体保护焊接接头组织和力学性能的影响。结果表明:不同热输入下的焊缝金属显微组织主要以贝氏体和马氏体的混合组织为主,粗晶热影响区组织主要由板条马氏体和联合贝氏体组成。随着热输入增大,粒状贝氏体占比增多,板条块亚结构由平行分布的细长条状向粗大块状转变,焊缝金属的冲击韧性先升后降。当热输入为17 kJ/cm时,焊缝金属显微组织中的短条状板条贝氏体、板条马氏体和细小的粒状贝氏体相互交织且分布均匀,使得焊缝金属韧性高,且分散度较小。在14~20 kJ/cm热输入条件下,焊缝金属、熔合线处、热影响区的-50℃冲击吸收功最低值分别为105、190、166 J;焊缝金属与母材的抗拉强度相差不大,焊材与母材匹配性良好,都能获得强韧性匹配良好的焊接接头。The effect of heat input of 14-20 kJ/cm on the microstructure and mechanical properties of the 18 mm thick 800 MPa grade HSLA steel MIG welded joints was investigated by OM,SEM,EBSD as well as tensile and impact tests.The results indicate that the microstructure of the weld metals under different heat inputs is primarily composed of a mixture of bainite and martensite.The microstructure of the coarse grained heat affected zone(CGHAZ)is primarily composed of lath martensite and coalesced bainite.With the increase of heat input,the proportion of granular bainite increases,and the lath substructure changes from slender and parallel strips to coarse blocks,and the impact toughness of the weld metal firstly increases and then decreases.When the heat input is 17 kJ/cm,the short strip lath bainite,lath martensite and fine granular bainite in the weld metal microstructure are interlocked and evenly distributed,which makes the the weld metal have high thoughness and small dispersity.Under the heat input of 14-20 kJ/cm,the minimum value of the impact energy of the weld metal,the fusion line,the heat affected zone at-50℃ is 105,190,166 J,respectively.The tensile strength of the weld metal has little difference with that of the base metal,and the welding material and the base metal are well matched,and the welded joints with good strength and toughness matching are obtained.

关 键 词：热输入 低合金高强钢 显微组织 力学性能 

分 类 号：TG444.7[金属学及工艺—焊接]