16MnCrS5 Round Steel

16MnCrS5 (abbreviated as 1.7139) is a free-machining, case-hardening steel derived from 16MnCr5 through the addition of sulfur. It offers significantly improved machinability, making it suitable for the high-efficiency, mass production of precision transmission components. After carburizing and quenching, it retains the characteristic combination of a hard surface and a tough core, and is widely used in industrial parts—such as automotive transmission gears and precision shafts—that demand high machining efficiency.
 
16MnCrS5 Steel Composition:
Carbon content: 0.14%–0.19%,
Manganese content: 1.00%–1.30%,
Chromium content: 0.80%–1.10%,
Sulfur content: 0.02%–0.04%.
 
Balanced Strength and Toughness: After quenching and tempering, tensile strength exceeds 900 MPa while maintaining good toughness; surface carburizing yields a hardness of up to 60 HRC, extending service life to three times that of ordinary steels.
 
Excellent Machinability: Sulfide inclusions reduce cutting forces by 20% and tool wear by 15%; chip-breaking characteristics are significantly improved, leading to markedly higher production efficiency.
 
Good Heat Treatment Stability: Features excellent hardenability with cross-sectional hardness fluctuations of less than 3 HRC, maintaining stable mechanical properties even in high-temperature environments.