Although hot mill rolls and cold mill rolls are both core components of rolling mills, they form two distinct technical systems in terms of materials, performance, and manufacturing due to differences in their working environments. Hot mill rolls focus on heat resistance and thermal fatigue resistance, while cold mill rolls emphasize high hardness, high wear resistance, and high precision. Together, they support the entire production process of the modern steel industry from rough rolling to finish rolling.
1. Materials and Treatment for Hot Mill Rolls
Common materials: High-chromium cast iron, semi-steel, forged steel (e.g., 55CrNiMoV, 60CrMoV, etc.), requiring high heat resistance, thermal fatigue resistance, and high-temperature strength.Heat treatment: Quenching and tempering + surface hardening, hardness HS 35–55; the core must have good toughness to withstand impact loads.Key requirements: Maintain stability in a working environment of 700–800°C, resist thermal cracking and wear, and allow a certain amount of diameter wear.
2. Materials and Treatment for Cold Mill Rolls
Common materials: High-carbon chromium alloy steels (e.g., 9Cr2Mo, 9Cr3Mo, 8CrMoV, etc.), requiring high hardness, high wear resistance, and dimensional stability.Heat treatment: Surface hardening + low-temperature tempering, hardness HS 45–105 (work rolls can reach HS 90–105); some require chrome plating to enhance corrosion resistance.
Key requirements: Withstand high rolling forces, contact fatigue, and wear, while maintaining precise roll profile and mirror surface finish.
