Apr 11, 2020
The laser welding machine uses a high-energy pulse laser to focus and melt the target metal to weld between workpieces. This new welding technology is very effective, but if it is not properly operated, it will also cause hot or cold cracks. So how is welding crack produced by a laser welding machine?
The unbalanced rapid heating and cooling characteristics of laser welding make the whole joint in a complex stress state, which constitutes the mechanical factor of joint cracking; Laser welding is the synthesis of a series of unbalanced technological processes. In the process of rapid metallurgical solidification, the uneven distribution of components, and the quenched structure with low crack resistance will inevitably appear, which constitute the metallurgical factors to promote crack initiation.
There are three kinds of cracks in the welding process of laser welding machine: the crack of end product, the crack of liquefying, and the crack of reheat like. The crystallization crack is related to the composition inhomogeneity in the macroscopic region of the weld. The central area of the weld is the place where the liquid phase crystallization is the latest. The columnar crystals on both sides of the weld intersect here. At the same time, a large number of impurities with a low melting point also accumulate here, forming the central line segregation, thus reducing the bonding strength there. Under certain mechanical conditions, the crack occurs in this part.
Knowing the causes of cracks, we should pay more attention to the operation of the laser welding machine in our life, and try to avoid the welding defects caused by the operation reasons.