72. In a steel pouring ladle, the distance between the top of the ladle and the surface of the contents of the ladle is called
73. The purpose of injection of calcium into liquid steel is to
P. replace Al2O3 inclusions by CaO inclusions
Q. modify Al2O3 inclusions into calcium aluminate inclusions
R. reduce sulfur content of steel
S. reduce nitrogen content of steel
P. replace Al2O3 inclusions by CaO inclusions
Q. modify Al2O3 inclusions into calcium aluminate inclusions
R. reduce sulfur content of steel
S. reduce nitrogen content of steel