Hadfield Steel Recrystallization Annealing

Manganese hard steel is a special case: you can't soften it again by normal annealing. Once you've welded it, carbides precipitate at the grain boundaries. The stuff becomes brittle and crack-sensitive during welding. If you want to relieve the stress, you have to quench the steel, not cool it slowly. But be careful: if you heat it too much during welding, you'll ruin the structure. Best to keep the interpass temperature low and cool the area well between passes.