Heterogeneous microstructure
A non-uniform microstructure with varying grain sizes, phase fractions, or compositions, caused by uneven heat treatment.
Physical-Chemical Mechanism of Action
A heterogeneous microstructure forms when the metal is heated or cooled unevenly during the welding process or cooling. This leads to local changes in grain size and chemical composition.
Metallurgical Relevance & Risks in Welding
A heterogeneous microstructure can cause various problems, such as increased hardness or toughness in certain areas, which can lead to cracks and component failure. Additionally, it can cause uneven stress distribution and damage.
Workshop Practice & Instructions
To avoid a heterogeneous microstructure, uniform heat treatment is essential. This includes proper preheating and cooling of the parts, as well as adhering to welding parameters such as temperature and time. For complex parts, special heat treatment methods like isothermal or gradient cooling may be helpful.