Effect of Post-weld Heat Treatment on Properties of Friction Welded Joint Between TC4 Titanium Alloy and 40Cr Steel Rods  

作　　者：Honggang Dong Lianzhen Yu Dewei Deng Wenlong Zhou Chuang Dong 

机构地区：[1]School of Materials Science and Engineering, Dalian University of Technology [2]State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology [3]Key Lab of Materials Modification (Dalian University of Technology), Ministry of Education

出　　处：《Journal of Materials Science & Technology》2015年第9期962-968,共7页材料科学技术（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (Grant No. 51374048);the National Basic Research Program of China ("973 Program", Grant No. 2011CB013402);the Fundamental Research Funds for the Central Universities (DUT13ZD209);the State Key Laboratory of Advanced Welding and Joining (AWJ-M14-06), Harbin Institute of Technology, Harbin, China

摘　　要：Dissimilar metal joining of Ti-6AI-4V （TC4） titanium alloy to as-rolled 40Cr steel rods was conducted with friction welding, and the effect of post-weld heat treatment （PWHT） on the microstructure and mechanical properties of the resultant joints was investigated. The average tensile strength of the as-welded joints reached 766 MPa and failure occurred in 40Cr steel base metal. However, after PWHT at 600℃ for 0.5, 1, 2 and 3 h, the tensile strength of the joints decreased and fracture happened through the interface with quasi-cleavage features. The bending angle of specimens was improved from 9.6° in as-welded state to 32.5° after PWHT for 2 h. The tensile strength of the joint was enhanced by martensitic transformation near the interface in as-welded state. Sorbite formed near the interface in PWHT state and improved the bending ductility of the joint. TiC brittle phase formed at the interface after PWHT for 0.5 h and deteriorated the tensile strength and bending ductility of the joint. After PWHT for 2 h, no TiC phase was detected at the interface. The microhardness on the interface in as-welded state was higher than that after PWHT, indicating that the decrease of microhardness around the interface could be accompanied by degradation of tensile strength but improvement of bending ductility of the joints.Dissimilar metal joining of Ti-6AI-4V （TC4） titanium alloy to as-rolled 40Cr steel rods was conducted with friction welding, and the effect of post-weld heat treatment （PWHT） on the microstructure and mechanical properties of the resultant joints was investigated. The average tensile strength of the as-welded joints reached 766 MPa and failure occurred in 40Cr steel base metal. However, after PWHT at 600℃ for 0.5, 1, 2 and 3 h, the tensile strength of the joints decreased and fracture happened through the interface with quasi-cleavage features. The bending angle of specimens was improved from 9.6° in as-welded state to 32.5° after PWHT for 2 h. The tensile strength of the joint was enhanced by martensitic transformation near the interface in as-welded state. Sorbite formed near the interface in PWHT state and improved the bending ductility of the joint. TiC brittle phase formed at the interface after PWHT for 0.5 h and deteriorated the tensile strength and bending ductility of the joint. After PWHT for 2 h, no TiC phase was detected at the interface. The microhardness on the interface in as-welded state was higher than that after PWHT, indicating that the decrease of microhardness around the interface could be accompanied by degradation of tensile strength but improvement of bending ductility of the joints.

关 键 词：Dissimilar metal joiningFriction weldingTitaniumSteelPost-weld heat treatmentlntermetallic 

分 类 号：TG453.9[金属学及工艺—焊接] TG441.8