Influence of Post-welding Heat Treatment on the Microstructure and Tensile Properties of X65 Pipeline Steel Welding Joints
In order to study the effect of post-welding heat treatment on the microstructure and tensile properties of X65 pipeline steel welding joints,multi-layer and multi-pass welding of X65 pipeline steel was carried out using electrode arc welding,and the welding joints were subjected to post-welding heat treatment at 550℃for 2 hours.The results show that the heat treatment effectively improved the microstructure of the weld zone,transforming the coarse columnar crystals into fine blocky structures,and promoting the precipitation of carbides.Mechanical property tests show that the tensile strength of the heat-treated weld increased to 590 MPa,and the elongation after fracture reached 31.2%,significantly better than the untreated weld.The analysis suggests that the combined effects of grain refinement,carbide precipitation,and grain bound-ary pinning contribute to the improvement of the room temperature tensile strength and toughness of the welding joints.
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