Effects of Inoculation on Microstructures and Mechanical Properties of Resistance Spot Welded Magnesium Alloy Joints
Resistance spot welded magnesium alloy joints contain the nugget and heat affected zone (HAZ), and the weld nugget of magnesium alloy generally contains two different microstructures, the cellular dendritic crystals at the edge of the nugget and the equiaxed dendritic crystals in the center of the nugget. Characteristics of cellular dendritic crystals make the cellular dendritic crystals zone to be the weak area, and the more unfortunate thing is that it is located in the high-stress zone, which further degrades the mechanical properties of the joints. Based on this conditions, inoculation would be tried to refine the cellular dendritic crystals in order to improve the mechanical properties of resistance spot welded magnesium alloy joints. Al-10Sr was chosen as the inoculant in this experiment. As the addition of Al-10Sr increases from zero to 1.4mg, the average width of cellular dendritic crystal zone decreases from 332μm to 58μm while the microstructure tends to be refined, accordingly, tensile shear load of the joints increases by 24.3% from 2.379 KN to 2.959 KN. It is favorable to select a relative higher content of Al-10Sr addition to improve the mechanical properties of the spot welded magnesium alloy joints.
Wenzhe Chen, Xingjun Liu, Pinqiang Dai, Yonglu Chen and Zhengyi Jiang
H. X. Sun et al., "Effects of Inoculation on Microstructures and Mechanical Properties of Resistance Spot Welded Magnesium Alloy Joints", Advanced Materials Research, Vols. 482-484, pp. 2142-2147, 2012