X80管线钢焊接热影响区组织性能改善措施

采用热模拟试验方法,研究了一种X80管线钢热影响区在不同冷速、焊接线能量和峰值温度下的金相组织和力学性能变化规律。试验表明:适当提高焊缝热影响区冷速可以改善其组织和强韧性能;在相同焊接线能量的条件下,试验X80钢焊接热影响区的临界区、粗晶区冲击韧性最差并分别出现一处谷值,细晶区强度最差;采用较小线能量焊接有利于改善热影响区综合强韧性;采用高熔敷率复合高效多丝埋弧焊低线能量化焊接工艺、随焊加速冷却工艺、焊后焊缝及热影响区局部中频正火热处理工艺,可以有效改善X80管线钢热影响区强韧匹配性能。

Discussion on Improving Processing Measure of Welding HAZ Microstructure Performance for X80 Pipeline Steel

By using the thermal simulation test, the changing rules of the metallurgical structure and mechanical properties of weld HAZ of X80 pipeline steel under different cooling rates, welding heat inputs and peak temperatures were discussed in this essay. The tests showed that： Appropriate increase of the cooling rate in the weld HAZ can improve the microstructure, strength and toughness of the weld HAZ;under the same welding heat input, the impact toughness of the critical zone and the coarse grain zone are poor and a valley occurs respectively in these two zones, the strength of the fine grain zone is the lowest;welding adopting a relatively low heat input is beneficial to improve the comprehensive strength and toughness of weld HAZ. According to analysis result, a welding procedure with high deposit rate, high-efficiency multi-wire submerged arc welding and lower heat input, a simultaneous accelerate cooling process, and a local intermediate-frequency normalizing treatment of weld ＆ HAZ post-welding can effectively improve the comprehensive strength-toughness performance of weld HAZ of pipeline steel.