Effect of Rotational Speed on Microstructure and Mechanical Properties in Submerged Friction Stir Welding of ME20M Magne
- PDF / 3,699,526 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 64 Downloads / 225 Views
JMEPEG https://doi.org/10.1007/s11665-019-04205-w
Effect of Rotational Speed on Microstructure and Mechanical Properties in Submerged Friction Stir Welding of ME20M Magnesium Alloy Wenming Liu, Yifu Shen, Chao Guo, Ruiyang Ni, Yinfei Yan, and Wentao Hou (Submitted August 17, 2018; in revised form May 20, 2019) Submerged friction stir welding of magnesium alloys has not been well investigated to date. ME20M is an important lightweight magnesium (Mg) alloy with enhanced yield strength and heat resistance that merits further research. In this paper, submerged friction stir welding of the ME20M Mg alloy was carried out using different parameters for the underwater cooling. Defect-free weld joints were produced, and the macrostructure, microstructure, tensile properties, and hardness were investigated. The results show that by increasing the rotational speed, the grain size of the weld nugget increased, the tensile strength of the joint decreased, and the microhardness of the different weld zones decreased. The finest obtained grain size was about 3.5 lm in the weld nugget at a rotational speed of 1100 rpm. The highest tensile strength achieved was 183.2 MPa, which was 76.32% of the base metal. The highest and lowest hardness values of the weld joint were obtained at rotational speeds of 1100 and 1600 rpm, respectively, in the weld nugget and heat-affected zones. Keywords
ME20M magnesium alloy, mechanical properties, microstructure, rotational speed, submerged friction stir welding
1. Introduction Friction stir welding (FSW) was invented in 1991 as an advanced joining method and has been investigated by many researchers. During FSW, a rotational tool travels along the length of the plates to be welded and the associated stirring action produces a highly plastic joint with refined grains (Ref 1, 2). Magnesium (Mg) alloys are increasingly important lightweight structural materials for application in the aerospace, automotive, and shipbuilding industries because of their low density and high specific strength (Ref 3). Mg alloys have a hexagonal close-packed structure with a limited number of room temperature deformation mechanisms, such as basal slips and tensile twinning (Ref 4). Recently, improvements in the formability of Mg alloys at room temperature have been demonstrated by the addition of rare earth (RE) elements, such as cerium (Ce) and lanthanum (La) (Ref 4-8). The ME20M Mg alloy (also previously known as MB8), which contains manganese (Mn) and cerium (Ce) (nominal composition Mn-1.3-3.2 wt.% and Ce-0.150.35 wt.%), is known to have enhanced yield strength and heat resistance compared with the other Mg alloys; however, it Wenming Liu, Yifu Shen, Chao Guo, Ruiyang Ni, Yinfei Yan, and Wentao Hou, College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics (NUAA), Yudao Street 29, Nanjing 210016, PeopleÕs Republic of China. Contact e-mail: [email protected].
Journal of Materials Engineering and Performance
has been minimally studied to date. Improving the ductility of magn
Data Loading...
