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为查明X65钢高频焊管焊接区冲击功异常的原因,通过光学显微镜和X射线衍射对母材、焊缝及焊接热影响区进行微观研究.结果表明,显微组织对金属低温韧性有显著影响.当块状铁素体组织较多时,焊接区晶粒尺寸大,硬度小,冲击功低;当多边形铁素体组织较多时,焊接区晶粒尺寸小,硬度大,冲击功高.通过合理的热处理工艺,可在焊接区获得粒状铁素体组织,提高冲击功,改善焊缝和焊接热影响区低温韧性.
In order to find out the reason of the abnormal impact energy in the welding zone of X65 steel high frequency welded pipe, the microstructure of the base metal, weld and HAZ were studied by optical microscope and X-ray diffraction.The results show that the microstructure has significant effect on the low temperature toughness Effect.When the massive ferrite structure, the weld zone grain size, hardness, impact energy is low; when polygonal ferrite more, the welding zone grain size small, high hardness, high impact energy.Through Reasonable heat treatment process, can be obtained in the welding zone granular ferrite, improve impact energy, improve the weld and heat affected zone low temperature toughness.