Diffusion-Controlled Phase Transformation

A transformation process where the reorganization of the crystal structure is coupled with site-changing atomic movements. The kinetics depend primarily on temperature and diffusion coefficients.

Diffusion-controlled transformation is slow and takes time because atoms have to migrate first. In welding, this means: if you cool the weld too quickly, you get hard, brittle microstructure that tends to crack. So you have to control the cooling so that the structure can transform cleanly. But too hot or too long is also not good, then the material becomes soft and loses strength. Stick to the specified preheat and interpass temperature and give the weld the necessary time to cool after welding.

MetallurgieSchweißtechnik