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 ... oxide skin is small. In 500 tempering, it will appear secondary hardening peak. The peak value is around 55HRC with the ...