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以特高压输电铁塔用Q420低合金高强钢为研究对象,采用理论分析与试验的方法对其焊接性能进行了评价。结果表明,试验钢存在淬硬倾向,有一定的冷裂纹敏感性。焊接时需进行预热,理论计算的预热温度为77℃。实际焊接试验预热50℃时,焊接接头未发现裂纹,焊接接头抗拉强度为566 MPa,D=42 mm,180°弯曲合格。焊缝和热影响区冲击韧性优良,热影响区由于粗化冲击性能略低于焊缝,同时有轻微的硬化现象。焊接焊接接头焊缝区为先共析铁素体+针状铁素体组织,过热区为粗大贝氏体,正火区为细小的铁素体+珠光体组织。
Taking the low-alloy and high-strength steel Q420 of UHV transmission tower as the research object, the welding performance was evaluated by theoretical analysis and test. The results show that the test steel has the tendency of harden and has some cold crack sensitivity. Preheat welding, the theoretical calculation of the preheating temperature of 77 ℃. The actual welding test preheated 50 ℃, no cracks found in the welded joints, welded joints tensile strength of 566 MPa, D = 42 mm, 180 ° bending qualified. Weld and heat affected zone impact toughness, heat affected zone slightly lower than the cohesive impact of the weld, with a slight hardening phenomenon. Weld welded joint weld zone for the first eutectoid ferrite + acicular ferrite, superheat zone for coarse bainite, normalizing zone for the small ferrite + pearlite organization.