X80级管线钢埋弧焊焊缝韧性波动研究

研究分析了西气东输二线用X80级钢18.4mm厚热轧卷板的成分和组织特点。TEM分析表明,18.4mm厚X80级热轧卷板在板厚1/4和1/2处,晶界均比较纯净,组织以针状铁素体为主。针对这种高钢级厚板管线钢埋弧焊接条件下出现的焊缝韧性波动,采用SEM、能谱分析等对焊缝微观组织、冲击断口形貌、成分偏析、焊缝夹杂物、焊丝纯净度等进行了分析。研究结果表明,焊缝原始奥氏体晶粒大小对韧性有显著影响,晶界AlN、硫化物析出是形成焊缝光滑脆性断口的主要原因,焊缝中高熔点氧化物夹杂也会引起冲击值下降。

Research on SAW Weld Toughness Fluctuation of X80 Grade Pipeline Steel

The composition and structure characteristics of X80 grade pipeline steel,which was used in the 2nd Westeast Gas Pipeline Project,had been researched and analyzed in this article. TEM analysis showed that,in thickness 1/4 and 1/2 of X80 grade hot roiled coil with 18.4mm thickness,the grain boundary was purity and organization was acicular ferrite. Aiming at the toughness fluctuation of the high grade thick plate pipeline steel submerged arc welding. SEM and energy spectrum analysis had been used to analyze weld microstructure, appearance of impact fracture,composition segregation,weld inclusions, welding wire purity, etc.. Approved by the research consequence, original austenite grain size has significant effect on weld toughness. And grain boundary AlN, sulfide separation are the main reasons of forming smooth brittle fracture on the welds. High mehing oxide inclusions in the welds also could cause the decrease of impact value.