Crater pipe
Crater porosity are cavities in the crater of the weld, formed by rapid solidification. They weaken the weld end mechanically.
Physical-Chemical Mechanism
When welding, metals are compressed under high pressure and cooled quickly. This can lead to rapid solidification, with air bubbles or gas residues forming in the molten pool. These bubbles start to grow when the metal cools and pressure conditions change. They then form crater pores in the crater at the end of the weld.
Metallurgical Relevance & Risks in Welding
Crater pores can affect the mechanical behavior of the weldment, as they are weak points. They can lead to cracks or fracture and reduce the strength of the weld. They can also act as initiation sites for corrosion if they come into contact with water.
Workshop Practice & Action Guidelines
To minimize crater pores, it is important to ensure controlled cooling of the weld. This can be achieved by using cooling water or special shielding gases. Pressure conditions during welding should be controlled so that no air bubbles enter the molten pool. Careful cleaning of the weld and the use of high-quality filler materials can also help avoid crater pores.