Researches of Mechanical Properties of Welded Joint Based on the Method of Micro Sample

Abstract

Welding is one of the most important ways to connect metal materials. The mechanical properties of the welded joint are not uniform, which affects the overall strength of the joint. Through the traditional experimental method, it is difficult to test the mechanical properties of materials in different regions of welded joint. With 2219 aluminum alloy friction stir welding (FSW) joint as the research object, two kinds of micro sample methods, nanoindentation test and micro specimen tensile test, were respectively adopted for testing. Through these experimental studies, the mechanical properties of materials were obtained in different regions of welded joint: such as the elastic modulus, yield limit, ultimate strength and so on. The changes of the mechanical properties of the welded joint were analyzed from the weld center to the base metal. Through the data comparison, the results of the two kinds of micro test methods are basically consistent with each other. The elastic modulus in the center of the weld is relatively large, and decreases gradually with the transition to the base material. The yield limit and the ultimate strength in the center of the weld are relatively small, and increase gradually with the transition to the base material. The elongation is relatively high in the heat affected zone and relatively low in the weld zone and the base metal zone. These studies also provided the data basis for the research on the strength of welded joint.