The solidification sequences of three kinds of hypereutectic multi-component white cast irons with 4 to 5 mass% C were clarified for a basic study to apply them to a welding deposit material in the hard facing technique. To reveal the phases crystallized from liquid, quench tests during thermal analysis were Introduced into this experiment.
In the case of Fe-5% (Cr, V, Mo, W, each)-4-5% C irons, four types of carbides, MC, M2C, M7C3 and M3C were found to exist in the matrix.
In the iron with 4% C, MC carbide precipitates as a primary phase, and austenite as a quasi-primary phase. After the precipitation of the two different primary phases, L→γ+MC eutectic reaction takes place, followed by L→γ+M7C3 eutectic reaction. Next, L→γ+M3C eutectic reaction continues and solidification completes with L→γ+M2C eutectic reaction.
The solidification sequence of the iron with 5% C is as follows : L0→Primary MC+L1, L1→quasi-primary M7C3+L2, L2→(γ+M7C3) eutectic+L3, L3→(γ+M3C)eutectic+L4, and finally L5→(γ+M2C) eutectic.
In the case of Fe-5% (Cr, V, each)-2% (Mo, W, each)-4% C iron, γ, MC, M7C3 and M3C exist in the matrix. The following solidification sequence was revealed :
L0→Primary MC L1, L1→(γ+MC) utectic+L2, L2→(γ+M7C3) eutectic+L3and finally L3→ (γ+M3C) eutectic.
