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利用热模拟技术及光学显微镜、透射电镜研究了在不同冷却时间(t8/5)条件下,大能量焊接EH40钢板模拟焊接热影响区组织和性能的变化规律。试验结果表明,模拟焊接热影响区组织主要是由粒状贝氏体、铁素体和珠光体组成;随着t8/5时间的增加,焊接热影响区的组织由粒状贝氏体和少量的准多边形铁素体组成转变为以粗大的等轴铁素体和珠光体为主,同时M-A岛的数量先增多后减少,尺寸逐渐增大,形状也由块状变为长条状,大颗粒状的M-A岛极易引起脆性解理断裂,导致冲击韧性下降;模拟焊接热影响区的冲击韧性总体水平较高,随着冷却时间(t8/5)的增加,韧性呈现出先降低后升高再降低的趋势。
The changes of microstructure and properties of simulated heat-affected zone (HAZ) welded by large energy EH40 steel under different cooling time (t8 / 5) conditions were investigated by means of thermal simulation and optical microscope. The results show that the microstructure of simulated HAZ is mainly composed of granular bainite, ferrite and pearlite. With the increase of time t8 / 5, the microstructure of HAZ is composed of granular bainite and a small amount of quasi- The polygonal ferrite composition changes to coarse equiaxed ferrite and pearlite, while the number of MA islands increases first and then decreases, the size gradually increases, and the shape also changes from massive to elongated, large granular MA island can easily lead to brittle cleavage fracture, resulting in the decrease of impact toughness. The impact toughness of the simulated HAZ is higher. With the increase of cooling time (t8 / 5), the ductility decreases first and then increases and then decreases the trend of.