ASTM F1537(UNS R31537) Cobalt Chrome Molybdenum Alloy

UNS R31537 is a low-carbon, non-magnetic, wrought cobalt-chromium-molybdenum (CoCrMo) alloy. It is classified as “Alloy 1″ under the ASTM F1537 standard and is a critical material in the field of surgical implant manufacturing.

This alloy is renowned for its high strength, excellent corrosion resistance, and superior wear resistance. Its performance is derived from a precise chemical composition design: Chromium (Cr) content of 26.0-30.0% primarily forms a passive film, which imparts corrosion resistance; Molybdenum (Mo) content of 5.0-7.0% refines the grain structure and enhances strength; the addition of low carbon (C ≤ 0.14%) and nitrogen (N ≤ 0.25%) further improves wear resistance through the formation of carbides and nitrides, while maintaining ductility. Cobalt (Co) serves as the balancing element, forming the matrix of the alloy. It can be produced via powder metallurgy , which yields a more uniform microstructure and finer carbide particles, thereby enhancing fatigue strength. The material is typically supplied in a hot-worked or warm-worked condition to achieve an optimal combination of mechanical properties.

Based on these characteristics, UNS R31537 is widely used in the manufacture of load-bearing orthopedic implants, such as hip, knee, and shoulder joint prostheses, as well as fracture fixation devices. Long-term clinical experience has confirmed its favorable biocompatibility and reliability within the human body.