Effect of Post-weld Heat Treatment on Properties of Friction Welded Joint Between TC4 Titanium Alloy and 40Cr Steel Rods
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2015年第9期
论文作者：Honggang Dong Lianzhen Yu Dewei Deng Wenlong Zhou Chuang Dong
文章页码：962 - 968
摘 要：Dissimilar metal joining of Ti–6Al–4V（TC4） titanium alloy to as-rolled 40 Cr 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 40 Cr steel base metal. However, after PWHT at 600 °C 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. Ti C 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 Ti C 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.
Honggang Dong1,2，Lianzhen Yu1，Dewei Deng1，Wenlong Zhou1，Chuang Dong3
1. School of Materials Science and Engineering, Dalian University of Technology2. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology3. Key Lab of Materials Modification (Dalian University of Technology), Ministry of Education
摘 要：Dissimilar metal joining of Ti–6Al–4V（TC4） titanium alloy to as-rolled 40 Cr 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 40 Cr steel base metal. However, after PWHT at 600 °C 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. Ti C 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 Ti C 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.
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