Microstructural banding inhomogeneity
Band structure is a banded distribution of different phases or alloying elements in metals, which arises from hot rolling. It causes microstructural inhomogeneity and can lead to strength differences and cracks.
Physicochemical Mechanism of Action
Band structure occurs when metals segregate in certain directions during hot rolling. This leads to a banded distribution of different crystal phases or alloying elements.
Metallurgical Relevance & Risks in Welding
The microstructural inhomogeneity caused by band structure can lead to strength differences within the weld. This increases the susceptibility to cracks and hot cracking, especially when the metal is under mechanical load. Additionally, it can cause uneven stress distribution and thus lead to stress corrosion cracking risks.
Workshop Practice & Action Instructions
To minimize microstructural inhomogeneity due to band structure, it is important to properly calibrate and temper the metal before welding. This can be achieved by careful selection of rolling direction and speed. For heavily loaded applications, careful cooling and a possible post-weld heat treatment (PWHT) should be considered to improve microstructural homogeneity.