Microstructural characteristics and mechanical properties of friction stir welding joint of 1420 aluminum-lithium alloy(PDF)
长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]
- Issue:
- 2016年05期
- Page:
- 110-117
- Research Field:
- 汽车与机械工程
- Publishing date:
Info
- Title:
- Microstructural characteristics and mechanical properties of friction stir welding joint of 1420 aluminum-lithium alloy
- Author(s):
- MENG Yao; LI Hui
- School of Materials Science and Engineering, Chang’an University, Xi’an 710061, Shaanxi, China
- Keywords:
- mechanical engineering; friction stir welding; 1420 aluminumlithium alloy; microstructure; texture; hardness; mechanical property
- PACS:
- TG4
- DOI:
- -
- Abstract:
- The mechanical properties of weld joint in Al-Li alloy could be enhanced by using the friction stir welding (FSW). Microstructure, textures, precipitate phase, hardness distribution of 10 mm thick weld joint in 1420 Al-Li alloy after FSW were studied by using the SEM, TEM, EBSD methods, etc. Furthermore, interactions between microstructures and mechanical properties were discussed. The results show that the microstructures of three zones in the joint are all different, and they all vary from matrix. The stir zone is composed of recrystallization textures. The lath structures and grains distort in thermos-mechanically affected zone. Because of the heat effect arising from FSW, grains in heat affected zone are forced to become bigger than those in matrix, but the shape is similar to that of the matrix. The types of major texture in the stir zone are S{123}<634> , R{124}<211>, and the volume fraction of texture is 18.9% and 18.1%, respectively. The main textures and their contents in thermos-mechanically affected zone and heat affected zone are similar to those in stir zone. But, in base metal (BM), Copper{112}<111>(13.5%) become the initial texture and volume fraction is 16.9%; meanwhile, the contents of other textures, such as S and R, have a sharp decrease in BM. In this study, the δ′ precipitate, known as Al3Li, is the only precipitate of 1420Al-Li alloy. According to matrix, heat affected zone, thermos-mechanically affected zone and stir zone in order. The content of δ′ precipitate decreases gradually, and finally, vanishes in the stir zone. The hardness of the joint is lower than that in matrix, and gradually decreases along the direction of the stir zone, thermos-mechanically affected zone, heat affected zone, and matrix direction. Also, the hardness of advancing side is always lower than that of retreating side. In this study, δ′ precipitate has little influence on microhardness of the weld joint, but the grain size will be the main influence factor.
Last Update: 2016-10-06