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JIS G4052 SCM415H Case Hardening Steel
SCM415H is a case-hardening steel in the Japanese JIS G4052 standard. The suffix "H" stands for Hardenability Band, meaning that in addition to meeting the basic chemical composition range of SCM415, this grade must pass a jominy test to ensure that its hardenability falls within the specified band, guaranteeing consistency in core hardness and hardened layer depth across different batches of material after heat treatment.
SCM415H is a low-carbon Cr-Mo alloy steel with a carbon content of approximately 0.12%~0.18%. Chromium (Cr≈0.85%~1.25%) and molybdenum (Mo≈0.15%~0.30%) are added to improve hardenability and resistance to tempering softening.
SCM415H steel is almost never used directly in the annealed state. Instead, it undergoes a carburizing (or carbonitriding) + quenching + low-temperature tempering process to achieve high surface hardness and high wear resistance, while maintaining good toughness and high yield strength in the core, thus realizing the typical "hard outside, tough inside" performance of carburized parts.
SCM415H is widely used in automotive transmission gears, differential gears, drive shafts, piston pins, and various heavy-duty carburized parts. It is one of the most mainstream carburized gear steels in Japanese and JIS-standard mechanical equipment.
SCM415H is typically delivered in hot-rolled, annealed, or normalized condition (hardness ≤179~217 HB). This condition is primarily for ease of machining. Typical mechanical properties for the annealed condition are: tensile strength Rm≈440~600 MPa, yield strength ReL≥295 MPa, elongation after fracture A≥22%, and reduction of area Z≥50%~60%.
SCM415H is a low-carbon Cr-Mo alloy steel with a carbon content of approximately 0.12%~0.18%. Chromium (Cr≈0.85%~1.25%) and molybdenum (Mo≈0.15%~0.30%) are added to improve hardenability and resistance to tempering softening.
SCM415H steel is almost never used directly in the annealed state. Instead, it undergoes a carburizing (or carbonitriding) + quenching + low-temperature tempering process to achieve high surface hardness and high wear resistance, while maintaining good toughness and high yield strength in the core, thus realizing the typical "hard outside, tough inside" performance of carburized parts.
SCM415H is widely used in automotive transmission gears, differential gears, drive shafts, piston pins, and various heavy-duty carburized parts. It is one of the most mainstream carburized gear steels in Japanese and JIS-standard mechanical equipment.
SCM415H is typically delivered in hot-rolled, annealed, or normalized condition (hardness ≤179~217 HB). This condition is primarily for ease of machining. Typical mechanical properties for the annealed condition are: tensile strength Rm≈440~600 MPa, yield strength ReL≥295 MPa, elongation after fracture A≥22%, and reduction of area Z≥50%~60%.
