What are the causes of weld cracking?

2024,08,27

Weld cracking in the weld has the following causes: stress, constraints, rigidity, chemical composition, the gap left in the weld, current, weld channel, base material cleanliness. These factors may be the cause of weld cracking.

Although there are many reasons for weld cracking, but on different occasions is caused by a variety of factors, there are two or three factors. But regardless of several factors, which must be a major factor. There are also a variety of conditions have no effect, only by a factor causing weld cracking.

Therefore, the weld cracking must first correctly analyze the cracking of the main factors and secondary factors, according to the main factors causing cracking, secondary factors to take appropriate measures to solve.

Welding process to form the weld is the electrode and the base material after the two current high temperature melting to form a weld, is the electrode and the base material from solid to liquid, high-temperature liquid is thermal expansion, cooling into a solid is contraction. As a result of thermal expansion and contraction, the natural welding structure to produce stress. Some welded structures are inherently constrained and rigid.

Welding process is a solid into a liquid, that is, from the solid state into a liquid (usually said iron), and then from the liquid state into a solid state, the formation of the weld. Liquid to solid (that is, iron to grain). The process of turning molten iron into crystals is the crystallization process.

Parent material temperature low position first began to crystallize, gradually to the middle of the weld to extend the position of the weld, the weld in the middle of the final crystallization. Due to the role of thermal expansion and contraction, the welding structure by the stress or constraints or rigidity, so that the parent material grains can not be connected together, light in the middle of the weld small cracks, heavy in the middle of the weld obvious cracks.

Even if the chemical composition of the base metal and electrode are good, by the welding structure of the constraints, rigidity and welding process generated by the impact of stress, there will be cracks or cracks.

If the chemical composition of the base metal and electrode is not good (carbon, sulfur, phosphorus, etc. high); or weld gap is too large, the base material in the edge of the weld too many impurities, or current is too large, and the welding speed is too fast, too slow, the weld channel is too wide, and other factors will make the cracking of the weld to aggravate the situation.

Author:

Mr. Richard

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info@jiade-group.com

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