According to ASTM A2 16 standard, ordinary carbon steel castings, such as the most commonly used WCB castings, generally do not need post-weld heat treatment after welding repair. However, if the weld repair area exceeds 65 square centimeters (10 square inch) or the weld repair depth exceeds 20% or 2.5 centimeters of the wall thickness of the casting (whichever is smaller), post-weld heat treatment is needed to eliminate internal stress.
Other low-alloy carbon steel castings, such as WC6, WC9, C 12A, need preheating before welding, temperature maintenance during welding and heat treatment after welding to eliminate internal stress and prevent delayed cracks in castings. For details, please refer to ASTM A2 17 and ASME standards or corresponding domestic standards.