Mechanisms of joint formation throughout semisolid stir welding of AZ91 magnesium alloy

作     者：V. A. HOSSEINI H. AASHURI A. KOKABI V. A. HOSSEINI;H. AASHURI;A. KOKABI

作者机构：Materials Science and Engineering Department Sharif University of Technology 

出 版 物：《Transactions of Nonferrous Metals Society of China》 (中国有色金属学报（英文版）)

年 卷 期：2013年第23卷第9期

页      面：2585-2590页

核心收录：

学科分类：080503[工学-材料加工工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0802[工学-机械工程] 080201[工学-机械制造及其自动化] 

主　　题：AZ91 magnesium alloy semisolid joining Mg-Zn interlayer mechanical stirring metallurgical bonding 

摘      要：Joining in the semisolid state is considered a possible method to join alloys to each other. The mechanisms taking part in semisolid stir welding of AZ91 alloys were investigated. Two 7.5 mm-thick AZ91 pieces and a 2 ram-thick Mg-25%Zn interlayer piece were placed in a heating plate. After holding for 3 min at a desired temperature, the weld seam was stirred by a rotational tool. The heating plate was travelled on a trolley at a constant speed of 4.6 cm/min. In addition, one sample was welded without interlayer. Evolution of welding as a function of stirring rate, tool shape and temperature was studied throughout this welding process with scanning electron and optical microscopes. Interlayer decreases the joining temperature and assists to investigate the possible semisolid stir welding mechanisms. Increasing temperature and stirring rate, and using round stirrer instead of grooved stirrer increase the stir zone width. The results show that some possible mechanisms are helpful to achieve a proper metallurgical bonding in the welding process, such as oxide layer disruption, liquid phase blending, globule joining, and liquid penetration to the base metal, merging a group of globule into stir zone from the base metal.