Biodur 108 Cr-Mn-n Steel Round Bar

Product Description

BioDur 108 is a premium, nickel-free high-nitrogen austenitic stainless steel developed primarily for the medical industry. It was engineered to eliminate the risk of nickel-allergic reactions while providing mechanical properties that far exceed traditional stainless steels like 316LS.

1. Key Performance Characteristics

• Nickel-Free: The nickel content is maintained at a maximum of 0.05%, making it the gold standard for orthopedic implants and jewelry.

• Superior Strength: It offers approximately double the yield strength of annealed 316L.

• Non-Magnetic: It remains fully austenitic and non-magnetic even after heavy cold reduction ($ \mu < 1.01 $).

• Biocompatibility: It exhibits high resistance to pitting and crevice corrosion in synthetic body fluids, often outperforming 316L in PREN (Pitting Resistance Equivalent Number) calculations.

2. Chemical Composition

The alloy uses high levels of Manganese and Nitrogen to stabilize the austenite phase in the absence of Nickel.

3. Mechanical Properties (Annealed Round Bar)

The high Nitrogen content acts as a powerful solid-solution strengthener.

• Ultimate Tensile Strength: $\geq 896$ MPa ($130$ ksi)

• Yield Strength (0.2% Offset): $\geq 552$ MPa ($80$ ksi)

• Elongation: $\geq 40\%$

• Hardness: $\approx 25$ HRC (Higher than standard 300-series)

4. Primary Applications

BioDur 108 is most commonly supplied as round bars for precision machining in the following sectors:

• Orthopedic Implants: Bone screws, plates, marrow pins, and spinal fixation components where high fatigue strength is required.

• Medical Instruments: Surgical tools that must be non-magnetic and highly durable.

• Hearing Health: Components for cochlear implants or middle ear devices (where nickel sensitivity is a concern).

• High-End Jewelry: Piercing studs and watch components for consumers with hypersensitivity to nickel (Contact Dermatitis).

5. Machinability & Processing

Because of its high work-hardening rate and high nitrogen content, BioDur 108 is more challenging to machine than 316L.

• Tooling: Use of carbide tools and rigid setups is recommended.

• Speeds: Generally requires lower cutting speeds and higher feeds to prevent the tool from glazing over the work-hardened surface.

• Standards: Often meets ASTM F2229 (Standard Specification for Wrought Nitrogen Strengthened 21Cr–23Mn–1Mo Low Nickel Stainless Steel Bar and Wire for Surgical Implants).