Bonding of Aluminum Alloys in Compound Casting
- PDF / 4,549,879 Bytes
- 13 Pages / 593.972 x 792 pts Page_size
- 56 Downloads / 206 Views
RODUCTION
THE increasing demand for lightweight structures in automotive and aerospace industries has led to the wide application of aluminum (Al) alloys.[1–3] Because of the structure complexity and particularly variation in local material property requirement, one single type of Al alloy does not satisfy the component service demand.[4,5] The common solution for this problem is to form a structure by joining dissimilar metals with different fabrication procedures, such as friction stir welding (FSW),[6–8] gas metal arc welding (GMAW),[9–11] and laser beam machining (LBM).[12–15] Although those joining techniques can provide good weld quality and production flexibility with less energy input, the complex welding process and limitations in workpiece geometry and dimension have limited their wide applications.[16–18] Compound casting is a relatively simple and cost-effective processing. It achieves the bonding of two metals by casting the liquid material over the solid material, and forms a continuous metallic transition zone between two metals.[19,20] Nevertheless, Al alloys are difficult to bond during compound casting process. Owing to the formation of oxide layer on the surface of Al alloys, the wettability of
JIAN FENG, BING YE, LIJIE ZUO, QUDONG WANG, HAIYAN JIANG, and WENJIANG DING are with the National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, P.R. China. Contact e-mail: [email protected] QIGUI WANG is with General Motors Global Propulsion Systems, 800 North Glenwood Ave, Pontiac, MI 48340-2920. Manuscript submitted January 9, 2017.
METALLURGICAL AND MATERIALS TRANSACTIONS A
the liquid Al on the solid Al is rather poor during overcasting.[10,21] Papis et al. [22] introduced zinc layer on the Al alloy substrate to obtain the bonding of wrought and cast Al alloys. The Zn layer acts as a barrier to replace the oxide layer on the Al alloys, improving the wettability of the substrate and promoting the formation of continuous and flawless metallic interfaces. Runber et al.[23] further investigated the effect of Zn layers with various thickness on Al/Al compounds during high-pressure die casting. It was reported that the initial thickness of the Zn layer has strong influence on the microstructure and thickness of the reaction diffusion zone, but interestingly exerts little effect on mechanical properties of the compounds. Liu et al.[24] studied the effect of Zn layer thickness on the microstructure and mechanical properties of the joints under pressure by squeeze casting. The tensile strength of the joints was improved by 10 pct with squeeze casting compared to that by gravity casting. Because of the relatively low thermal stability of the Zn layer, the casting has to be precisely controlled to get good quality joint. As a result, more research has been devoted to different coating materials that are able to sustain the liquid Al during overcasting process. Ni and Cu coating has been reported in the literature i
Data Loading...
