The main cause of hot cracking is the stress concentration at the crack, which can be improved from the aspect of solidification mode. Insufficient pouring refers to insufficient pouring temperature or unreasonable design of pouring riser.

Excessive current will not only overheat the molten pool and make the columnar crystals coarse, but also increase the fusion ratio, so that the parent metal with greater hot cracking tendency will enter the weld too much, thus increasing the hot cracking tendency; If the welding speed is too fast, the strain rate of weld will increase during crystallization, and the hot cracking tendency will also increase.

Extended data

Selection skills:

1. Choose masterbatch with small hot cracking tendency and strictly control impurity content: various aluminum alloys have different hot cracking tendencies during welding. Among them, industrial pure aluminum and rust-proof aluminum are less prone to hot cracking.

2. Correct selection of filler metal: increase the number of low melting point crystals to "self-heal" cracks.

3. Correct selection of welding method and welding parameters: The welding method with concentrated heat energy can realize rapid welding and prevent the formation of coarse columnar crystals with strong directionality, thus reducing the tendency of hot cracking.

4. Choose resistance welding equipment, mainly by welding, not filling welding wire, etc.