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本文以V型缺口试件的冲击功及50％FATT值为韧性指标对HQ80C钢的母材、不同热输入的模拟粗晶区和MIG多层焊接头的熔合线韧性进行了评定;采用光学金相、扫描电子显微镜和金属薄膜透射电子显微镜等方法对母材、模拟粗晶区和MIG焊接头的断口形貌、晶粗大小、组织特征、碳化物的析出和分布状况以及M—A组元的形态及亚结构进行了观察;测定了MIG焊接接头的软化倾向,表明: HQ80C钢焊接时,粗晶区晶粒长大倾向比一般C—Mn钢小; 粗晶区韧性对线能量变化敏感。小线能量时以低碳马氏体为主的粗晶区韧性较好,随线能量增大,粗晶区韧性降低; 采用小线能量进行MIG焊接头的熔合线韧性相当优良,且接头无明显软化区。
In this paper, the impact toughness of V-notch specimens and the 50% FATT value as toughness index were used to evaluate the toughness of the fusion lines of the base metal of HQ80C steel, the simulated coarse grain zone with different heat input and MIG multi-layer welded joint. Phase, scanning electron microscopy and metal thin-film transmission electron microscopy on the fracture morphology, grain size, microstructure, precipitation and distribution of carbides and the M-A component The morphology and substructure of MIG welded joints were observed. The softening tendency of MIG welded joints was measured. The results show that when HQ80C steel is welded, the grain growth tendency of coarse grain is smaller than that of normal C-Mn steel. The toughness of coarse grain is sensitive to the change of energy . The low-carbon martensite-based coarse-grained zone has a good toughness and the toughness of the coarse-grained zone decreases with the increase of the line energy. The weld line toughness of the MIG welded joint using the small-line energy is quite good, Clear softening area.