Interface Migration
Grain boundary migration is the process by which grain boundaries or phase boundaries move due to thermal activation and diffusion. This affects grain growth and recrystallization.
Physical-Chemical Mechanism of Action
Grain boundary migration occurs when atoms at the boundaries between different crystals or phases move under the influence of temperature. This diffusion causes grain boundaries to shift and affects grain growth.
Metallurgical Relevance & Risks in Welding
At too high temperatures during welding, grain boundary migration can lead to uneven crystal growth. This can cause grain coarsening and reduce the steel's mechanical properties, including lower toughness and increased risk of cracking.
Workshop Practice & Action Instructions
To minimize grain boundary migration, it is important to control welding temperatures so they are not too high. Optimal cooling time and uniform cooling of the weld help regulate grain growth. For severely coarsened steel, recrystallization via hardening or austenitizing may be required.