Grain refinement
Grain refinement is the creation of a fine-grained metal structure through inoculants or rapid cooling. A fine grain increases strength and toughness, but also prevents cracks and distortion.
Physico-chemical mechanism of action
Grain refinement is achieved by using inoculants or rapid cooling. These methods hinder crystal growth during solidification, resulting in a finer grain structure.
Metallurgical relevance & risks in welding
A fine grain increases the strength and toughness of a metal, but it also makes it more susceptible to cracks and distortion. Excessive grain refinement can lead to hot cracking and solidification cracking.
Workshop practice & action instructions
Use inoculants like silicon or titanium for grain refinement. Ensure rapid cooling, but avoid overheating. An optimal grain structure is achieved through targeted control of cooling steps and the use of suitable inoculants.