Welding repair process requirements for cast steel components of railway vehicles

Welding repair of cast steel should be carried out before heat treatment of the cast steel. All welding repair operations should be completed as much as possible in the flat welding position.

The groove and the range of 15-50mm on both sides should be cleaned thoroughly, and there should be no rust, oil, water or other foreign objects. When conducting welding repair and arc striking operations, it is necessary to prevent the arc from damaging the surface of cast steel components, and arc striking operations should not be carried out on non welding repair surfaces of cast steel components. During the welding repair process, it is necessary to maintain the interlayer temperature of the welded joint not lower than the specified preheating temperature.

When multi-layer welding low alloy cast steel( σ Attention should be paid to slow cooling after welding (b ≥ 580MPa), and welding slag should be removed after cooling. For welded junctions larger than 3mm, welding at two or three locations is allowed simultaneously, and the interlayer temperature should be ensured to be 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 should be used for welding repair. When repairing cast steel components with a required welding strength greater than 500MPa, multiple layers of low current, slow welding speed, and narrow weld beads should be used to fill the groove of the welding repair. The welding rod should swing along the longitudinal direction of the groove. When welding, it is advisable to first weld the bottom layer of the groove, and then weld both sides and the middle part until the groove is fully filled. After each layer of welding is repaired and slag is removed, a slag hammer can be used to strike the surrounding area of the weld bead appropriately, which can to some extent eliminate internal welding stress.