Abstract
The fading behaviour in magnesium-treated cast irons has been investigated. The main results are:
(1) The fading behaviour hardly depends on the melting atmosphere (air, Ar-gas).
(2) The amount of magnesium-consumption through reactions with oxygen, sulphur, or nitrogen in melts does not exceed 20∼30% of the total consumption.
(3) The covering of magnesium-treated cast irons with MgO decreases the fading rate of magnesium a little, while the covering with BaF2, CaF2 and MgF2 increases it considerably in the order.
(4) It has been clarified that these results are satisfactorily explained if the escape of magnesium from the melt is mainly due to the floating-up of magnesium gas bubbles.
