摘要
采用埋弧焊工艺制备含镧(La)高锰奥氏体钢(Fe-24%Mn)焊缝金属,研究了La含量对焊缝金属微观组织、非金属夹杂物类型和尺寸分布及力学性能的影响。结果表明,当La含量依次为0、0.042%、0.098%时,焊缝金属中典型夹杂物分别为Mn-Al-Si氧化物+MnS复合夹杂物、La_(2)O_(3)夹杂物、La 2 O 2S夹杂物,夹杂物平均尺寸分别为0.56、0.43、0.48μm,数量密度分别为4845、5605、5950个/mm 2。与未添加La的焊缝金属相比,适量La的加入明显细化了焊缝金属凝固组织,并提高了其力学性能。其中La含量为0.042%的焊缝金属表现出最佳的力学性能,其断裂方式为韧性断裂,断口形貌表现为密集分布的小尺寸等轴韧窝。这可以归因于细小且数量众多的La_(2)O_(3)与初生奥氏体点阵的错配度低,有效促进了奥氏体异质形核,细化了凝固组织;另外,位于韧窝底部的La_(2)O_(3)与基体之间良好的结合能力有助于延缓裂纹扩展至夹杂物时的应力集中,从而增强了焊缝金属的力学性能。
By using submerged arc welding,the high manganese austenitic steel(Fe-24%Mn)weld metals containing lanthanum(La)were prepared,and the effects of La content on the microstructure,non-metallic inclusion types,size distribution,and mechanical properties of the weld metals were investigated.The results indicate that with La content sequentially at 0,0.042%,and 0.098%,the typical inclusions in the weld metal are Mn-Al-Si oxides+MnS composite inclusions,La_(2)O_(3)inclusions,and La 2 O 2 S inclusions,respectively.These inclusions have average sizes at 0.56,0.43 and 0.48μm,and number densities at 4845,5605 and 5950 per mm 2,respectively.Compared with weld metals without La addition,the introduction of a moderate amount of La significantly refines the solidification structure of the weld metal and enhances its mechanical properties.The weld metal with a La content of 0.042%exhibits optimal mechanical performance,demonstrating ductile fracture with a fracture surface characterized by densely distributed small equiaxed dimples.This can be attributed to the low lattice mismatch between the fine and numerous La_(2)O_(3)inclusions and the nascent austenite,effectively promoting austenite heterogeneous nucleation and refining the solidification structure.Furthermore,the strong binding ability of La_(2)O_(3)located at the base of the dimples with the matrix aids in delaying stress concentration as cracks propagate to the inclusions,thereby improving the mechanical performance of the weld metals.
作者
胡明峰
李光强
张金帅
王红鸿
万响亮
曹玉龙
Hu Mingfeng;Li Guangqiang;Zhang Jinshuai;Wang Honghong;Wan Xiangliang;Cao Yulong(Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education,Wuhan University of Science and Technology,Wuhan 430081,China;State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,Wuhan 430081,China;Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking,Wuhan University of Science and Technology,Wuhan 430081,China)
出处
《武汉科技大学学报》
CAS
北大核心
2023年第5期321-329,共9页
Journal of Wuhan University of Science and Technology
基金
国家自然科学基金资助项目(U1860205,U20A20277,51971165)
湖北省重点研发计划资助项目(2021BID003).
关键词
镧
埋弧焊
高锰奥氏体钢
焊缝金属
夹杂物
韧窝
La
submerged arc welding
high-Mn austenitic steel
weld metal
inclusions
dimple
