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采用CO2气体保护焊,研究了不同的焊接热输入对低合金高强钢ASTMA572GR.65钢在预热与不预热条件下焊接热影响区组织和性能的影响。研究表明,在小线能量(10kJ/cm)下,Nb(C,N)等第二相粒子在粗晶区能起到抑制晶粒长大的作用,使得晶粒比较小,而大线能量(40kJ/cm)下,这些粒子完全溶解,几乎没有起到对粗晶区晶粒长大的抑制作用。另外,小线能量(10kJ/cm)下,焊前预热有利于生成较细小的淬硬组织,对GR.65钢粗晶区的韧性起有利作用,而大线能量(40kJ/cm)下焊前预热反而使粗晶区组织粗大,并生成上贝氏体等韧性很差的组织,会对整个焊接热影响区产生不利影响。
CO2 gas shielded welding was used to study the effect of different welding heat input on the microstructure and properties of the heat affected zone (HAZ) of low alloy high strength steel (ASTMA572GR.65) under both preheating and non-preheating conditions. The results show that the second-phase particles such as Nb (C, N) can inhibit the grain growth in the coarse-grained region under the small line energy (10kJ / cm) (40kJ / cm), these particles completely dissolved, almost no grain growth in coarse grain growth inhibition. In addition, the small wire energy (10kJ / cm), the preheating before welding is conducive to the formation of smaller hardened tissue, the toughness of the GR.65 steel coarse grain region play a beneficial role, and large line energy (40kJ / cm) However, the preheating before welding coarsely coarsens the coarse-grained zone and produces a tissue with poor toughness such as upper bainite, which adversely affects the entire welded heat-affected zone.