Advantages: it can destroy the ingot casting, steel grain refinement, and eliminating the defect in microstructure, thus making steel tissue close-grained, with improved mechanical properties.

Causes to the laminar defect of the umbrella bone steel occurring in the process of cold forming are analyzed by chemical analysis and microstructure analysis.

Through analyzing the actual producing process and microstructure of the Sn-bronze castings with thedefect of stannic sweat, the cause resulting in the defect in the castings has been discussed.