Study Of Effect Of Cutting Heat Affected Zone On Structure And Performance Of Q345E Low Alloy Steel Welded Joints

As the train speed increased, welded bogie frame under the dynamic load is significantly increased, requiring that welded bogie frame must have sufficient strength and fatigue performance. Therefore, in the design, production and manufacturing process on the welded joint after welding, the details of the processing requirements more stringent, more sophisticated, it is great practical significance that safe and reliable operation of Fast Freight Car Bogie Frame Welding is ensured.In this paper, the main contents are as follows:in the existing cutting process, hardness, width, microstructure, grain size of heat affected zone Q345E low alloy steel with different thickness and the cut surface quality, microstructure are analysized. At the same time conventional mechanical properties and fatigue properties of welded joints of the heat-affected zone with cutting and removal cutting heat-affected zone are studied.The results show that:over-heated zone structure of 10mm,12mm plate flame cutting heat affected zone is ferrite and small amounts of granular bainite. Structure of over-heated zone of 12mm plasma cutting HAZ is martensite. Structure of the normalization area and recrystallization areas of heat affected zone of flame cutting and plasma cutting are ferrite and pearlite. With the incrment of plate thickness, increment of width of cutting heat-affected zone is not obvious, width of heat-affected zone of plasma cutting is narrower, compared with the flame cutting. Microstructure of welded joint of flame cutting and machining is same substantially, heat-affected zone of flame cutting has little effect on crack resistance of welded joints, tensile strength, yield strength, percentage elongation and area reduction rate of welded joint are equivalent to that of machining. Side bending, back bending 180°are qualified. Heat-affected zone of flame cutting has little influence on the fatigue properties welded joints with removed or retained strengthening of Q345E low-alloy steel and has little effect on fatigue performance of T-type and HY-type corner joints. Therefore, it is feasible to weld flame cutting edge, under the premise of ensuring the quality of cutting surface.