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用脉冲燃烧型焊条对Q235钢进行了手工自蔓延立焊焊接,研究了立焊所形成的温度场与获得的焊缝合金组织。结果表明:脉冲燃烧型焊条中三段长度不同的高热焊药形成了三个有效熔池,两个低热造渣段只维持焊条燃烧和造渣而不形成熔池,在二者共同作用下每个熔池的温度场都不相同;焊缝合金相组成基本相同,但由于熔池温度场变化,造成从第一熔池到第三熔池晶粒逐渐减小,形成焊缝组织梯度变化,且第三熔池晶粒取向比第一和第二熔池明显;凝固后各熔池间存在明显的界面,在近母材端为冶金结合,而在近熔敷金属表面端结合较差,有轻微夹渣。
The pulse self-propagating vertical welding of Q235 steel was carried out by using pulsed combustion electrode. The temperature field and welding alloy structure obtained by vertical welding were studied. The results show that three effective puddles are formed in the three sections of pulsed combustion electrode with different lengths of hot melt flux. The two low-temperature slagging sections only maintain the electrode for combustion and slagging without forming puddle. Under the combined action of the two, The temperature field of the weld pool is different; the weld alloy phase composition is basically the same, but due to the change of the temperature field of the weld pool, the grains from the first weld pool to the third weld pool are gradually reduced to form the gradient of weld microstructure, And the grain orientation of the third molten pool is more obvious than that of the first and second molten pools. There is a clear interface between the molten pools after the solidification, the metallurgical bond at the near parent metal end, and the poor bonding at the near-deposited metal surface, A slight slag.