Thermal Stress Relief Annealing

You do stress-relief annealing to get rid of residual stresses from welding or machining. Heat the part evenly to a temperature below the transformation temperature, hold it there for a while, then cool slowly and controlled. If you do it right, the workpiece stays dimensionally stable and won't crack during final machining. But be careful not to get too hot, or you can ruin the structure. Exact temperatures and times depend on the material, so follow the data sheet.