Effects of Postweld Heat Treatment on Microstructure and Properties of Laser-Welded Ti-24Al-15Nb Alloy Joint

Journal Article · Fri Nov 15 04:00:00 EST 2019 · Journal of Materials Engineering and Performance

DOI:https://doi.org/10.1007/S11665-019-04351-1· OSTI ID:22970367

Wang, Lin; Sun, Daqian; Li, Hongmei; Shen, Chengjie ^[1]

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1. Jilin University, Key Laboratory of Automobile Materials of Ministry of Education, School of Materials Science and Engineering (China)

The microstructure evolution and mechanical properties of laser-welded joints of Ti-24Al-15Nb alloy under different postweld heat treatment (PWHT) conditions were systematically investigated. The results show that the microstructure is very sensitive to PWHT temperatures. The weld zone consists of B2 and O phases after PWHT. With the PWHT temperatures increasing from 850 to 1000 °C, the amount of O phase decreases gradually, while the grains of O precipitates become coarser. After PWHT, there are some thin acicular O precipitates in heat-affected zone (HAZ), and the decomposition of α{sub 2}-phase caused by niobium diffusion can be observed in the HAZ. The PWHT can significantly increase the microhardness of joints, resulting from O phase precipitation hardening effect. The tensile strength and elongation of joints can be remarkably improved after PWHT, which was closely related to the strengthening effect of O precipitates and slip transmission between O and B2 phases. In addition, the results indicate that the best mechanical properties can be achieved only when the number and size of O phase and B2 phase are the best match.

• OSTI ID: 22970367
• Journal Information: Journal of Materials Engineering and Performance, Journal Name: Journal of Materials Engineering and Performance Journal Issue: 11 Vol. 28; ISSN 1059-9495; ISSN JMEPEG
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALLOYS
HEAT AFFECTED ZONE
HEAT TREATMENTS
LASER WELDING
MICROHARDNESS
MICROSTRUCTURE
PRECIPITATION HARDENING
TENSILE PROPERTIES