Microstructure and crack sensitivity of laser-fusion zones of Ti-46 mol % Al-2 mol % Mo alloy |
| |
Authors: | A Hirose Y Arita K F Kobayashi |
| |
Affiliation: | (1) Department of Welding and Production Engineering, Faculty of Engineering, Osaka University, 2-1, Yamadaoka, Suita, 565 Osaka, Japan |
| |
Abstract: | Laser surface melting and laser welding were performed on Ti-46 mol % Al-2 mol % Mo using a 2.5 kW CO2 laser. Microstructures of the fusion zones were changed in the following way as the cooling rate increased: massive 2+massive +lamellar( 2+ ) massive 2+massive ![gamma](/content/w4175j6130627100/xxlarge947.gif) ![rarr](/content/w4175j6130627100/xxlarge8594.gif) 2. In laser surface melting, a single-phase structure of 2 was seen when the calculated average cooling rates between 1773 and 1273 K were above approximately 4000 Ks–1. In laser welding, the microstructure of the fusion zones was mainly composed of massive 2+massive +lamellar. The hardness of the fusion zones increased with increasing cooling rate and the single-phase structure of 2 showed hardness above 500 Hv. While all of the laser surface-melted zones included cracking, in laser welding, crack-free welds could be obtained at traverse speeds below 50.0 mm s–1 and pre-heating temperatures above 573 K. As a result, cracking was prevented by selecting optimum welding parameters which result in calculated cooling rates between 1073 and 873 K below approximately 30 Ks–1 and the hardness of the fusion zones below approximately 400 Hv. In tensile tests, the laser-welded specimens without weld cracking fractured in the base metal. Thus, laser welding can be applied to the joining of Ti-46 mol % Al-2 mol % Mo. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|