630 stainless steel, also known as 17-4 PH (precipitation hardening), is a high-strength, corrosion-resistant alloy that combines good machinability with excellent mechanical properties. It is often used in aerospace, chemical, and other high-performance industries.
Carbon Content and Hardness
630 stainless steel has a carbon content of about 0.07%-0.15%. The hardness of 630 stainless steel is influenced by the precipitation hardening process, which involves aging the steel at a specific temperature to form fine precipitates that increase strength and hardness. In its annealed condition, 630 stainless steel typically has a Brinell Hardness (BHN) of 190-230 and a Rockwell B (HRB) hardness of 95-100.
Heat Treatment and Hardness
Through precipitation hardening, 630 stainless steel can achieve a hardness of 40-45 HRC (Rockwell C scale). The aging process significantly improves its mechanical properties, including hardness, tensile strength, and resistance to stress corrosion cracking.
Factors Affecting Hardness
- Carbon content: Low carbon content helps prevent carbide formation and improves weldability without compromising strength.
- Precipitation hardening: The precipitation hardening process enhances the strength and hardness of 630 stainless steel, making it suitable for high-stress applications.
- Grain structure: The microstructure after aging is key to achieving optimal hardness and strength.
Hardness in Applications
630 stainless steel is widely used in industries that require a combination of strength, hardness, and corrosion resistance, such as aerospace, chemical processing, and marine applications. It is often used in turbine blades, valve components, and other high-strength parts.