中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 27 No. 2 February 2017 |
（1. Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China;
2. Capital Aerospace Machinery Company, Beijing 100076, China;
3. State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China;
4. Key Laboratory for Advanced Materials Processing Technology,
Ministry of Education, Tsinghua University, Beijing 100084, China;
5. China Academy of Launch Vehicle Technology, Beijing 100076, China;
6. School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China;
7. Beijing Institute of Astronautics Systems Engineering, Beijing 100076, China）
Abstract:Three kinds of welds were made using low frequency pulse current variable polarity tungsten inter gas (LPVPTIG) with argon shielding, direct current TIG (DCTIG) with helium shielding and high frequency pulse current variable polarity TIG (HPVPTIG) with argon shielding, respectively. It was found that macrosegregation bands with large amount of thick continuous eutectics and microporosities formed in the LPVPTIG weld due to the fluctuation of the pulse varied heat input. Only microsegregation existed in the DCTIG weld and HPVPTIG weld. However，the HPVPTIG weld had lower extent of Cu microsegregation since its welding speed was slower. The tensile results indicated that the mechanical properties of the weld decreased with the increase of the segregation extent of Cu and porosities, and LPVPTIG weld had lower tensile properties in the longitudinal direction than those in the transverse direction due to the macrosegregation bands.
Key words: 2219 aluminum alloy; fusion welding; macrosegregation; microsegregation; mechanical behavior
