When designing steel castings, the sensitivity of the mechanical properties of cast alloys to the wall thickness of steel castings must be considered. When thick wall steel castings solidify at last, it is easy to produce defects such as shrinkage cavity (looseness), coarse grain and component segregation. Refer to the relevant reference books for the critical wall thickness TW of various cast alloy steel castings in sand casting. When the weight of steel castings exceeds 10kg, there is no clear requirement for the critical wall thickness of cast carbon steel. Moreover, according to the experience of similar products, the area with a wall thickness of 53 shown in Figure 1 and the hot joint with a diameter of 57.4 shown in Figure 2 can ensure that the internal structure and mechanical properties are qualified through reasonable setting of riser and cold iron.
In sand casting, with the same wall thickness, the solidification speed of the inner wall of the steel casting is slower than that of the outer wall, the mechanical properties of the inner wall are also lower than that of the outer wall, and cracks are easy to occur at the junction of the inner and outer walls. Generally, the inner wall of steel castings should be set thinner than the outer wall. The inner wall thickness of product k141 is 15mm and the outer wall thickness is 14mm. Obviously, the inner wall thickness is slightly greater than the outer wall thickness. After communicating with the customer on this point, the customer replied that due to the needs of product design, the wall thickness of crystal production cannot be changed. Therefore, the product quality can only be guaranteed by reasonably setting risers and cold irons.
