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Jiang Shaosong 1 and Li Baoyong 1, 2 and Liu Yang 2 and Zhang Kaifeng 1
Academic Editor:Woo-Jin Song
1, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
2, Beijing Hangxing Machinery Co. Ltd., Beijing 100013, China
Received 24 January 2014; Accepted 14 April 2014; 13 May 2014
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
The multilayer sandwich structure was widely used in the aerospace in order to meet the requirements of both lightweight and high strength [1, 2]. Currently, SPF/DB technology is the main process to form the multilayer structure and it has been widely used. Furthermore, the titanium alloy sandwich is the most widely used multilayer structure in the field of aerospace [3]. However, conventional SPF/DB process has some disadvantages: (1) long DB time at high temperature makes the connection cycle time longer; (2) loading at high ambient temperature (about 900°C) makes the material performance lower and the forming die service life shorter; (3) long forming time (nearly 18-hour thermal cycle time) including heating and cooling time leads to the high cost and low productivity [4]. Therefore, it is an urgent need to look for a high efficient forming method.
When SPF/DB is combined with LBW, diffusion bonding of core sheet is replaced by laser welding. Thus, the diffusion bonding time for core sheets is eliminated and the cycle time will be shortened. It makes the process cost reduced and forming die service life longer. Compared with SPF/DB, the LBW/SPF process has many advantages such as increasing the yield of parts production and improving the parts performance and shortening the manufacturing time [5-9]. It is of much importance for fabricating the multilayer sandwich structure. TA15 is the near- α -type high temperature titanium alloy; it owns good overall performance and its long-term usage temperature is up to 500°C. This outstanding performance makes it a promising material used in the aerospace industry. In this paper, the LBW/SPF/DB combined process was developed to fabricate the TA15 titanium alloy sandwich structure with square grid and the microstructure of different regions was also studied.
2. LBW/SPF/DB Process...