The welding repair of steel castings should be carried out before the heat treatment of the steel castings. All welding repairs shall be completed in the flat position as far as possible.
The groove and the range of 15-50mm on both sides should be cleaned and free of rust, oil, water, and other foreign matters. During welding repair and arc striking operations, it is necessary to prevent electric arcs from damaging the surface of the steel casting, and it is not allowed to conduct arc striking operations on the surface of the steel casting that does not require welding repair. During the welding repair process, it is necessary to maintain the interpass temperature of the welded joint not lower than the specified preheating temperature.
When multi-layer welding low alloy steel castings（ σ B ≥ 580MPa) should pay attention to slow cooling after welding, and the welding slag should be removed after cooling. For welded junctions larger than 3mm, it is allowed to weld two or three places at the same time, and ensure that the interlayer temperature is greater than the required preheating temperature for the steel grade.
When the length of welding repair is greater than 200mm, the segmented back welding method shall be used for welding repair. When welding steel castings with a required weld repair strength greater than 500 MPa, the groove of the weld repair shall be filled with multi-pass multi-layer welding with small current, slow welding speed, and narrow weld bead. The welding rod should be swung along the longitudinal direction of the groove. When welding, it is advisable to weld the bottom layer of the groove first, and then weld both sides and the middle part until the groove is completely filled. After each layer of welding is repaired and slag removed, a slag removal hammer can be used to properly tap around the weld bead. This method can eliminate internal welding stress to a certain extent.