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在低温环境条件下进行输油管线钢焊接施工时,焊缝冷却速度较快,影响焊缝金属的结晶形态和焊缝金属中的杂质含量,从而影响焊缝和热影响区的力学性能。我国在环境温度低于-5℃下的管道焊接技术还处于探索阶段。按照国外焊接工艺规程,对-28℃～-15℃环境温度下X60输油管线钢焊接接头进行了力学性能试验。结果表明,低温环境对焊接接头的拉伸、面弯、背弯及刻槽锤断、硬度性能影响不明显;但对低温冲击韧性值有较大的影响,当层间温度小于55℃时,焊接接头的低温冲击韧性值出现一定的离散性,说明较快的焊缝冷却速度使焊缝金属的韧脆转变温度升高。
Under the condition of low temperature, the cooling rate of the weld line is relatively fast, which affects the crystal morphology of the weld metal and the impurity content in the weld metal, thus affecting the mechanical properties of the weld and the HAZ. China in the ambient temperature below -5 ℃ pipeline welding technology is still in the exploratory stage. According to foreign welding procedure, the mechanical properties of X60 oil pipeline steel welded joint under -28 ℃ ~ -15 ℃ ambient temperature were tested. The results show that low temperature has no obvious effect on the tensile properties, surface buckling, back bending and grooved hammering and hardness of welded joints, but has a great influence on low temperature impact toughness. When the interpass temperature is less than 55 ℃, The low temperature impact toughness of the welded joint appears a certain degree of dispersion, indicating that the faster weld cooling rate makes the ductile-to-brittle transition temperature of the weld metal increase.