The hardness of SUS630 is determined by both solution treatment and aging treatment. Aging temperature plays a key role, and hardness varies significantly with different heat treatment states.
1. Hardness after Solution Treatment
After solution treatment (heating at 1040–1060℃ followed by rapid cooling), the material has low hardness, typically 28–32 HRB (approximately 25–30 HRC lower limit). At this stage, the material exhibits excellent plasticity, making it suitable for subsequent machining processes such as cutting and stamping.

2. Hardness after Aging Treatment (standard process: hold 4 hours + air cooling)
The higher the aging temperature, the lower the hardness:
* 480℃ aging: hardness 39–45 HRC, commonly used for high-strength applications with significant strengthening effect.
* 550℃ aging: hardness 36–42 HRC, balances strength and toughness, widely applied in industry.
* 590℃ aging: hardness 33–38 HRC, improved toughness, moderate strength.
* 620℃ aging: hardness 30–32 HRC, good toughness, suitable for low-temperature, impact-resistant applications.