Mfg. spherical graphite iron - using magnesium silicide additive (promoted by rare earth metal) to moderate vigorous reaction and to improve prod.

摘要

An improved method of prodn. of spherical graphite iron (SGI) is achieved by treating molten cast Fe with an additive based on Mg2Si. The latter consists of 55-63 (pref. 58-62)% Mg;36-45 (pref. 37-42)% Si; and 0-1 (pref. 0-0.75)% of a rare earth metal. USE/ADVANTAGE - The additive moderates the reaction and improves the product. Specifically in an induction oven,, an alumina-graphite crucible is situated, whose surface is protected with Ar gas. The Mg (99.8)% is added as a bar and Si(98.5)% in pieces is placed on it, and a slow melt begins at 15-20kW. The oxidn. protecting gas is changed to H2/N2 and the remainder of the stoiciometric quantity of Si added during the melt. The product is poured out at 1100-1150 deg. C into a steel vessel. In the SGI process, 30 kg. of a melt contg. 3-6% by wt. C;2.2% by wt. Si;0.16% by wt. Mn;0.013% by wt. P;and 0.012% by wt. S was treated with 0.3% by wt. of the additive at 1500 deg. C. The additive was in block form and was introduced into the melt by dipping. A smooth reaction ensued to give SGI of enhanced properties.