Once cracks appear on the surface of stainless steel castings, not only is the repair workload heavy, but in severe cases, they may also be scrapped, causing significant economic losses. The main factors causing cracks in stainless steel castings are casting structure, casting process, etc. The following measures are generally adopted in production to prevent them：
1. Casting structure
When casting, it is necessary to comprehensively consider factors such as the structure, shape, size, wall thickness, and transition of the casting that affect the liquid and solid shrinkage of the casting, select appropriate process parameters, and prevent casting defects such as shrinkage and porosity. The design of the gating and riser system for castings should be reasonable. If cold iron and other process measures are to be used, the placement position should be reasonable, ensuring the compactness of the internal structure of the castings while avoiding stress concentration as much as possible.
2. Smelting
During the smelting process, try to reduce the content of harmful elements such as P and S, as well as the content of gases and inclusions such as N, H, O, etc. By using low phosphorus steel intermediate alloys, good results can be achieved.
3. Insulation
By appropriately extending the insulation time of the casting in the sand mold, the main goal is to control the unboxing temperature below 70 ℃, ensuring that the casting fully completes liquid and solid shrinkage in the sand mold, and avoiding stress concentration caused by external forces.
4. Falling sand
During the sand removal process of castings, it is strictly prohibited to pour water onto the sand mold and castings during boxing, and it is strictly prohibited to use strong external impact methods such as box collision to remove sand, in order to avoid the interaction between external forces and internal stresses in the castings that may cause cracks.
5. Cutting the riser
Select the appropriate hot cutting and gating process according to the casting conditions, ensuring that the starting temperature of hot cutting is not less than 300 ℃. During operation, the gas cutting gun and oxygen blowing tube use vibration cutting. After important gas cutting, cover the partition with asbestos cloth or heat treat it in the furnace in a timely manner. For castings with complex structures and special process measures such as upper crown and axial flow blades, secondary hot cutting is adopted.