Coarse grain annealing
Specific thermal treatment for the deliberate enlargement of austenite grain size to optimize specific magnetic or mechanical properties in specialty materials. The material is held at elevated temperatures for extended durations.
You do coarse grain buffering to prepare the structure for welding. You keep the material hot until the grains get really big. This makes the heat-affected zone tougher later and you avoid cracks. If you don't do it right or anneal too briefly, the grain stays too fine and the part becomes brittle. During welding itself, you have to be careful not to put in too much heat, otherwise you burn away the buffering again. Make sure the part is evenly at temperature everywhere and give it enough time. After annealing, let it cool slowly, then it'll be fine.