Microstructure and mechanical properties of friction welds between TiAl alloy and 40Cr steel rods

• Published in: Transactions of Nonferrous Metals Society of China Vol. 24; no. 10; pp. 3126 - 3133
• Main Authors: DONG, Hong-gang, YU, Lian-zhen, GAO, Hong-ming, DENG, De-wei, ZHOU, Wen-long, DONG, Chuang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2014
• Subjects: Alloy steels; Aluminides; Chromium steels; dissimilar metal joining; friction welding; Heat treatment; Intermetallic compounds; Intermetallics; post-weld heat treatment; Rods; steel; TiAl alloy; Titanium aluminides; Titanium base alloys; Titanium compounds; steel; dissimilar metal joining; friction welding; post-weld heat treatment; TiAl alloy
• ISSN: 1003-6326
• DOI: 10.1016/S1003-6326(14)63451-8

Direct friction welding of TiAl alloy to 40Cr steel rods was conducted, and the microstructure and mechanical properties of the resultant joints in as-welded and post-weld heat treatment (PWHT) states were investigated. The martensitic transformation occurred and brittle TiC phase formed near the interface due to C agglomeration, which degraded the joint strength and increased the microhardness at the interface in as-welded state. Feathery and Widmanstatten structure generated near the interface on TiAl alloy side. After PWHT at 580 °C and 630 °C for 2 h, the sorbite formed and C dispersed at the interface, leading to the increase of the joint strength from 86 MPa in as-welded state to 395 MPa and 330 MPa, respectively. The heat-treated specimen fractured with quasi-cleavage features through the zone 1 mm away from the interface on TiAl alloy side, but the as-welded specimen failed through the interface.