Transgranular Fracture
Transcrystalline fracture is a crack that does not run along grain boundaries and leads to fine pores. This increases the toughness of the material.
Physical-Chemical Mechanism of Action
Transcrystalline fracture occurs when the crack runs through the material rather than along grain boundaries. This leads to fine porosity and grain growth, enlarging the material's grain size.
Metallurgical Relevance & Risks in Welding
A transcrystalline fracture can lead to increased toughness, which may be beneficial in certain applications. However, it can also cause fine porosity and grain growth that make the material more susceptible to cracking. This can cause problems, especially under high mechanical loads.
Workshop Practice & Action Guidelines
To minimize transcrystalline fracture, it is important to ensure careful cooling of the weld. This can be achieved by using cooling water or special cooling gases. The cooling rate should be set so that the microstructure does not cool too quickly (which leads to glass-hard martensite) or too slowly (which leads to grain growth). An optimal cooling time of 10 to 20 seconds is often recommended, depending on the specific material.