1.heat crack

1) choose the crystallization temperature range narrow alloy castings, alloy because the crystallization temperature range wide, in its liquid and solid two phase absolute shrinkage is larger, have the tendency of hot tearing also. Such as grey cast iron and ductile iron solidification shrinkage is small, so the cracking tendency also; But cast steel, cast aluminum and malleable iron tendency of hot tearing is bigger. 2) reduce harmful impurity in the casting alloy, such as reduction of phosphorus and sulfur content in iron - carbon alloy, high temperature strength of casting alloy can be improved. 3) improve the mold and core rolled back. Rolled back the better, the smaller the mechanical stress, the less the possibility of cracking. Specific measures is to use organic binder mixed sand and core sand; Join in the sand and core sand materials such as wood chips or coke can be improved rolled back. 4) reduce the pouring, riser casting shrinkage, gate Settings should comply with the principles of solidification at the same time. 5) reasonably adjust alloy elements (the strict control of sulfur and phosphorus content in steel and iron), reasonable design of the casting

2.Cool crack

All measures for decreasing the casting or reduce internal stress of alloy brittleness, can prevent the formation of cold cracking. For example: the steel and cast iron of phosphorus can reduce the impact toughness of the alloy, increase the brittleness, easy to produce cold cracking tendency, therefore must strictly limit in the metal smelting, and casting after pouring, also don't early shakeout.