The 150 mm×150 mm billet of carbon and alloy constructional steel
high carbon steel and welding rod steel casts by R9 m 4 strand concaster at Shiheng Special Steel Works. Through optimized secondary cooling process modified 0.5~0.8 MPa water pressure
0.80~1.30 L/kg water ratio and 3 section manual water cooling process to 0.20~0.30 MPa water pressure
0.25~0.75 L/kg and automatic(water + gas)- water cooling process
the middle crack and bulging defects were eliminated and the rhomboidity
dispersed shrinkage and shrinkage cavity defects decreased by 50%~80%.