Mechanical Properties and Metallurgical Structure of Semi-Solid Metal 356 Aluminum Alloy with Semi-Solid Metal 7075 Aluminum Alloy investigated using a Transient Liquid Phase Bonding Technique

• Published in: Wārasān witthayāsāt læ thēknōlōyī Mahāwitthayālai Mahā Sārakhām Vol. 38; no. 1; pp. 102 - 112
• Main Author: Yongyuth Dunyakul
• Format: Journal Article
• Language: Thai
• Published: Mahasarakham University 01.02.2019
• Subjects: mechanical properties; semi-solid 356 aluminum alloy; semi-solid 7075 aluminum alloy; transient liquidphase bonding
• ISSN: 1686-9664

In this paper, factors affecting mechanical properties and metallurgical structure of semi-solid aluminum alloy grades 356 and 7075 were investigated by a transient liquid-phase bonding method. ZA 27 zinc alloys were used as coagulants (solders) in a liquid state during the welding process. Semi-rigid aluminum castings with butt joints were prepared as a cylindrical shape 12 mm in diameter, 45 mm length and ZA 27 zinc alloys were 12 mm in diameter, and 0.25 mm thick. Variables in this transient liquid-phase bonding method included 60 minutes and 120 minutes welding time, welding temperatures at 450, 500 and 550 degrees Celsius, compression pressure at 4 MPa, and the flow rate of argon gas atmosphere at 4 liters/min. According to the results, the physical characteristics of all samples were well bonded. The microstructure in the bond line showed that size of the grain had grown because of the heat during transient liquid-phase bonding. However, at temperature 550ºC and compressive holding time for 60 minutes some porosities showed after welding, and the tensile strength of all samples were broken in the bonded line. However, at temperature 500ºC and compressive holding time 60 minutes, the maximum average tensile strength at 103.06 MPa was in the bonded line area where the hardness properties were higher than in other areas. In short, transient liquid-phase bonding technique could reduce welding time when compared to the diffusion bonding process.