LAUSR

Mold is an extremely important and special basic technological equipment in industrial production and plays a very important role. As the most widely used hot work die steel, H13 die steel has excellent high hardenability, strength, toughness and softening resistance, etc.1–4) Thus, it can be employed to produce operating tools, which are repeatedly subjected to high temperatures and loads.5,6) such as die casting molds, hot rolling, hot extrusion and hot forging.7,8) However, characteristics of carbides, especially type and size, have significant effects on the mechanical properties of H13 die steel, such as toughness, yield strength and fatigue cracks, etc.4,6,9) So refining the characteristics of carbides is crucial in the manufacture process of H13 die steel. Carbide precipitates easily during solidification process due to the high V, Mo, Cr and C content,4) including MC (M=V mainly), M2C (M=Mo mainly), M7C3 (M=Cr mainly) and M23C6 (M= Fe and Cr mainly).7,10,11) Large carbides are mainly MC and M2C in H13 die steel.2) There are some researches have been studied on refining carbides (MC and M2C) in H13 die steel. Toshio Okuno12) analyzed the Effect of Pressure on Dendrite Structure and Characteristics of Carbides during Solidification Process of H13 Die Steel Ingot