Effect of calcium treatment of steel for castings

摘要

This paper covers a review of the published work and some recent research on the effects of calcium treatment of molten steel for castings. In addition to the well-known effect on steel cleanliness and mechanical properties, the paper also covers the effect of calcium treatment on the fabrication characteristics of steel for castings, such as fluidity, surface quality, porosity, shrinkage tearing and machinability. The additional experiments described in this paper cover the effects of calcium treatment on the fluidity, shrinkage tearing tendency and surface porosity tendency of some high-chromium steel castings. The improvement in fluidity obtained with calcium treatment allows to decrease the pouring temperature of austenitic stainless steel up to 60℃. CaSiBa treatment in high-chromium steel was beneficial for reducing shrinkage tears and surface porosities. The paper also discusses the various alloys and treatment processes applied for calcium treatment in steel foundries. In spite of the far better recovery obtained through deep injection, the regular lump-type higher-density, calcium-bearing ferroalloy addition is satisfactory in steel foundries, in most cases.