X80大变形钢管环焊缝试验研究

采用E9018-G焊条手工电弧根焊,用低组配药芯焊丝自保护焊和高组配焊条手工电弧焊填充盖面工艺焊接了X80钢级大变形钢管环焊缝,对环焊缝接头进行力学性能测试和金相观察分析。结果表明,两种焊接工艺评定结果符合API Std．1104标准要求。采用低组配药芯自保护焊焊接的焊缝冲击功和裂纹尖端张开位移值比采用高组配焊条手工电弧焊焊接的高。前者的焊缝组织为PF(多边化铁素体)+P(珠光体),后者的焊缝组织为 PF+IAF(针状铁索体)+P。二者熔合区的组织均为粒状贝氏体,粗晶区和细晶区没有淬硬马氏体组织出现,保证了热影响区具有很好的断裂韧性。

Experimental Study on Girth Welds of X80 High Deformability Pipeline

Girth welds of X80 high deformability pipeline were welded by self-shield flux-cored arc weld (FCAW) and manual shield-metal arc weld (SMAW). The FCAW used E9018-G electrode to weld root and under-matched flux-cored wires to fill welding and cap welding. The SMAW also used the same welding consumable to weld root, but the metal of the filler welding and cap welding is overmatched electrodes. The mechanical properties testing and metallography testing of girth welded joints were carried out. It was found that the qualifications of two welding procedures met the requirements of API Std. 1104. The test results of Charpy impact and crack-tip opening displacement of welded joints for FCAW are higher than that of welded joints for SMAW. The microstructure of FCAW is polygonal ferrite and pearlite . But the microstructure of SMAW is polygonal ferrite , intra-granular nucleated acicular ferrite and pearlite. Heat affected zones exhibit excellent fracture toughness. The reasons are that the microstructure of fusion zones is granular bainitic, and that there is no martensite in coarse grain heat affected zone and fine grain heat affected zone.