X80管线钢螺旋埋弧焊接头组织和冲击性能分析

Microstructure and Impact Performance of Spiral Submerged Arc Welded in X80 Linepipe

在焊接过程中X80管线钢焊接热影响区和焊缝组织性能产生显著变化,特别是焊接热影响区粗晶区的低温冲击性能变化明显,因此针对X80管线钢制订相应的螺旋埋弧焊工艺,对其螺旋埋弧焊管焊缝和热影响区粗晶区(CGHAZ)和细晶区(FGHAZ)的组织和冲击性能进行分析。结果表明,与母材相比,CGHAZ的晶粒尺寸较大,低温冲击韧性较低,韧脆转变温度在-20℃和-40℃之间;FGHAZ晶粒细小而均匀,是焊接接头冲击性能较好的区域,在-60℃时冲击韧性值达到144 J;同时通过扫描电镜分析了CGHAZ和FGHAZ常温冲击断口形貌,CGHAZ塑性断口区是小而浅的韧窝,而FGHAZ塑性断口区为大而深的韧窝。

The microstructure and properties of HAZ （heat affected zone） and welding line of X80 linepipe steel change significantly in welding process, especially the low temperature impact resistance of CGHAZ （coarse grained heat affected zones）. For this reason, the process of SSAW （Spirally Submerged Arc Welding） have been worked out to study the properties of welded joint .The results show that the grain size of CGHAZ is bigger and low-temperature impact toughness is lower than base metal. Furthermore, the brittle-to-ductile temperature is more than -40℃ but less than -20℃ .The fine and homogeneous grain can be acquired in FGHAZ and areas with better impact properties. The impact reaches 144J at -60℃. At the same time, the microscope of fracture surface with FGHAZ and CGHAZ was analyzed by SEM. The ductile fracture zone of CGHAZ has many small and shallow dimoles, and the ductile fracture zone of FGHAZ has many large and deep dimoles.