中碳钢点缝焊问题研究

熔核的一次结晶是点缝焊接头形成过程中的重要环节之一.熔核一次结晶的组织形态主要受其合金本身的因素(K、m、C_0、D)和工艺因素(G、R)的影响,并且对其接头的机械性能有着很大的影响。本文通过对中碳钢板点缝焊接头形成进行金相观察及其分析、研究,认为中碳钢板点缝焊熔核一次结晶的组织形态为“四周的树枝晶和心部的等轴晶”,并用“成分过冷”的理论初步进行了解释,提出了促进等轴晶发展的途径.同时,还对中碳钢板点缝焊接头进行了大量的拉剪试验,从规范的角度论述了保证接头质量的关键问题是:焊接过程中的热平衡问题。

The Study OnS pot and Seam Welding of Medium Carbon Steel

The primary crystal of molten metal is one of the important links in the process of spot and seamwelding joint.The structure of the primary crysta of molten metal,which prodnces an great effect on the mechnical property of the joint,is mainly effected by the factors of all oy it self and technology (K,m,Co,D and G,R). After a lot of metallographic observation,analysis and study on the joint of spot and seam welding of medium carbon steel plate,the author firmlg believes thathe structure of the primary crystal from molten metal of spot and seam welding of medium carbon steel plate is the around dendrite and the centre of the equiaxed crystal and at the same time,the author uses the theory of constitntional supercooling to explain this and suggests the way of promoting the development of equiaxed crystal. On the other hand,the author has done a lot of tensile and shearing tests on the joint of spot and seam welding of medium carbon steel plate. The author elaborates standerdly that the key problem of ensuring thequality of joint is the heat balance in wdling process.