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采用富Ar气体保护焊方法,使用φ1.6mm的MK.GHS80实芯气保焊丝对板厚为20 mm的HG785D钢进行对接焊,对焊接接头显微组织进行了观察,并对接头拉伸、弯曲、冲击等力学性能进行了检测,研究了热输入对焊接接头组织和性能的影响。结果表明,焊缝组织主要为针状铁素体+少量先共析铁素体,随着热输入的增加,焊缝中先共析铁素体含量逐渐增加,侧板条铁素体和粒状贝氏体组织减少;当热输入较低时粗晶区组织为板条贝氏体,随着热输入的增加,粗晶区组织逐渐由板条贝氏体转变为板条贝氏体+粒状贝氏体,当线能量达到32.2kJ/cm时几乎全部为粒状贝氏体;随着热输入增加,接头抗拉强度逐渐降低,焊缝冲击韧性先提高后降低,但影响有限,热影响区冲击韧性则逐渐降低,当热输入达到32.2 kJ/cm时接头性能恶化,焊接接头在线能量为23.8 kJ/cm时能获得优良的强韧性匹配。
Adopting the method of Ar-rich gas shielded welding, the HG785D steel with a thickness of 20 mm was welded by using φ1.6mm MK.GHS80 solid gas-insulated welding wire, the microstructure of the welded joint was observed, Bending, impact and other mechanical properties were tested to study the heat input on the welded joints and performance. The results show that the microstructure of the weld is mainly acicular ferrite + a small amount of pro-eutectoid ferrite. With the increase of heat input, the content of pro-eutectoid ferrite in the weld increases gradually. The ferrite and granular Bainite decreased; when the heat input is low, the coarse-grained zone is lath bainite. With the increase of heat input, the coarse-grained zone gradually changes from lath bainite to lath bainite + granular When the energy of the bainite reaches 32.2kJ / cm, almost all of them are granular bainite. As the heat input increases, the tensile strength of the joint decreases gradually and the impact toughness of the weld first increases and then decreases, but the impact is limited. The heat affected zone The impact toughness decreases gradually, and the joint performance deteriorates when the heat input reaches 32.2 kJ / cm, and the excellent toughness matching can be obtained when the welding joint energy is 23.8 kJ / cm.