Effect of Different Welded Structures on Mechanical Properties of TA2 Tube to Tubesheet Joints

Abstract

Four types of TA2 welded tubetotubesheet joints prepared by manual tungsten arc argonshielded welding technique are studied in this paper. The pullout tests and low cycle fatigue tests were performed to optimize welded structures of tube and tubesheet. The results show that fractures of welded TA2 tube and tubesheet samples occur at weld zone of TA2 steel tube for the pullout tests and low cycle fatigue tests. The extensiontubesheet welded joints have the maximum pullout forces and the best fatigue resistance, and the internalbore welded joint with 45 deg bevel occupies second place. Fractures are both initiated from weld toe of the outside of tube for the pullout tests and low cycle fatigue tests. Crack propagates along the direction of 45 deg for the pullout test. However, crack propagates perpendicularly to the direction of the applied load for low cycle fatigue test, and then fractures immediately parallel to the direction of the applied load. Fatigue striations with a spacing of about 10 خ¼m can be observed on the fatigue crack propagation zone. However, hemispheroidal dimples exist on instant rupture zone.