Fine-grained high-quality hot alloy steel,4Cr5MoSiV,high hardenability, high toughness, and fine-grained. Fine-grained high-quality hot alloy steel,4Cr5MoSiV,high hardenability, high toughness, and fine-grained. Smelting ... tempering. Tempering Hardness47-49HRCHardness53~55 HRCAir-quenching should be at a low austenitized temperature, small heat deformation, and in air-quenching ...