Characteristics of Surface Microstructures for Welded Joint of 7A52 Aluminum Alloy before and after Surface Nanocrystallization

Abstract:

The surface nanocrystallization process by high energy shot peening (HESP) was carried out on the TANDEM MIG welded joints surface of 7A52 aluminum alloy after artificial aging. The microstructure features of welded joints surface layer were systematically characterized by using optical microscopy (OM) ,transmission electron microscopy (TEM) observations and X-ray diffraction (XRD) analysis. Based on the experimental observation, the banded texture of 7A52 aluminum alloy base metal was eliminated after HESP. After 50min of HESP processing, the thickness of deformed layer in the base metal (BM), weld metal zone (WM) and heat affected zone (HAZ) was 50μm, 70μm and 60μm separately. Obtained from the TEM micrographs, the average grain size of surface layer in the base metal, weld metal zone and HAZ was about 20nm, 26nm and 32nm respectively. The size of grain in the weld metal zone and HAZ was larger than the base metal. Moreover, the distribution of nanocrystalline in the weld metal zone and HAZ was uneven compared with the base metal.

• Periodical: Advanced Materials Research (Volumes 602-604)
• Pages: 2078-2081
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.602-604.2078
• Online since: December 2012
• Authors: Rui Jun Xie, Yao Lu, Fu Rong Chen, Zhi Ming Shi
• Keywords: Aluminium Alloy, High Energy Shot Peening, Microstructure, Surface Nanocrystallization, Welded Joint

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