Which Stainless Steel Alloys are Nickel-Free and Cobalt-Free?

For certain applications, traditional alloys containing nickel and cobalt can present challenges. For example, when used in medical devices, these elements can trigger allergic reactions in some patients. This is where a new generation of stainless steel comes in—nickel-free and cobalt-free alloys.

This innovative material offers a winning combination of biocompatibility and exceptional performance. Below, we explore the advantages of these alloys, specifically Carpenter Technology’s BioDur® 108.

BioDur® 108: Superior Tensile Strength, Advanced Performance

BioDur® 108 is an essentially nickel-free austenitic stainless steel that utilizes a high nitrogen content to maintain its austenitic structure. Its unique composition offers several advantages over traditional nickel-containing alloys.

BioDur® 108 is:

• FDA-approved & EU MDR compliant 
• Essentially, nickel-free stainless steel alloy
• Strong and corrosion-resistant
• Developed in response to patient allergies

Superior Tensile and Fatigue Strength

BioDur® 108 boasts higher tensile and fatigue strength compared to popular nickel-containing alloys like 316L (ASTM F138), 22Cr-13Ni-5Mn (ASTM F1314), and 734 (ASTM F1586). Enhanced strength translates to greater durability and reliability in demanding applications.

High Toughness and Work Hardening

The high nitrogen content in BioDur® 108 contributes to its exceptional toughness and high work hardening rate, meaning it can withstand significant impact and deformation without compromising its integrity.

Exceptional Corrosion Resistance

BioDur® 108 delivers outstanding resistance to pitting and crevice corrosion, surpassing 316L and matching the performance of 22Cr-13Ni-5Mn and 734 alloys. 

Biocompatibility

BioDur® 108 is essentially free of nickel and cobalt, minimizing the risk of allergic reactions in patients. Nickel is one of the most common allergens worldwide. In fact, studies suggest that around 10% of the population may have a nickel allergy. 

When a nickel-containing implant is placed in the body, the immune system can misinterpret nickel ions released from the implant as a threat, which triggers an inflammatory response, leading to symptoms like redness, itching, swelling, and even implant loosening in severe cases.

While less common than nickel allergies, concerns are rising regarding potential health risks associated with cobalt, particularly with long-term exposure. Regulatory bodies are increasingly scrutinizing the use of cobalt in medical implants due to potential links to genotoxicity (cellular damage) and carcinogenicity (cancer development).

Non-Magnetic Properties

Traditional stainless steel with a ferrite phase can be magnetic, posing a problem for medical implants because some medical procedures require MRI scans. Magnetic implants can distort the scan image, making it difficult for doctors to diagnose issues. In severe cases, magnetic implants can even move or heat up during an MRI scan, potentially causing harm to the patient. BioDur® 108's lack of ferrite phase ensures it's essentially non-magnetic, making it MRI-compatible and avoiding these complications.

Microstructurally Consistent

BioDur® 108 is produced using the Electro-Slag Remelting (ESR) process, a process that ensures microstructural integrity and cleanness, further enhancing the material's performance and reliability.

Medical Applications

BioDur® 108's biocompatibility and exceptional performance make it a valuable material for various medical applications. Here's a closer look at some of its key uses:

• Orthopedics: BioDur® 108 excels in orthopedic implants due to its strength, durability, and corrosion resistance. Traditional stainless steel implants can sometimes fail due to a phenomenon called stress shielding, which occurs when the implant takes on too much of the stress that would normally be borne by the bone, weakening the bone around the implant. BioDur® 108's elasticity helps to mimic the natural properties of bone, reducing stress shielding and promoting long-term bone health. Additionally, its biocompatibility makes it suitable for components in joint replacements like hips and knees, promoting long-term implant success and reducing the risk of implant rejection due to allergies.
• 3D Printing: 3D printing with BioDur® 108 opens exciting possibilities for creating customized orthopedic implants. This technology allows for the creation of patient-specific implants with intricate designs that perfectly match individual anatomy, leading to improved implant fit, function, and long-term outcomes.
• Spine Surgery:  Spinal fixation devices require a delicate balance of strength, flexibility, and biocompatibility. BioDur® 108 delivers on all these fronts. It can be used in rods, screws, and plates to stabilize the spine during procedures like spinal fusions and deformity corrections.
• Dentistry:  BioDur® 108's biocompatibility and formability make it a valuable material in dentistry. It can be used in orthodontic appliances like braces and retainers, offering a safe and effective option for patients with nickel allergies.
• Surgical Instrumentation: The high strength and corrosion resistance of BioDur® 108 make it suitable for various surgical instruments. Scalpels, forceps, and other tools can be crafted from this material, ensuring exceptional durability and performance throughout demanding surgical procedures.

Industrial Applications

Beyond the medical field, BioDur® 108's unique properties offer advantages in various industrial applications. For example:

• Food Processing Equipment: Food processing equipment needs to be resistant to corrosion and maintain a high level of hygiene. BioDur® 108's exceptional corrosion resistance and smooth surface properties make it ideal for various components that come into contact with food, reducing the risk of contamination and ensuring food safety.
• Chemical Processing: BioDur® 108's excellent corrosion resistance allows it to withstand exposure to a wide range of chemicals, extending the lifespan of equipment and reducing maintenance costs.
• Hypoallergenic Jewelry: Wearing traditional jewelry can cause skin irritation for individuals with nickel allergies. BioDur® 108 offers a hypoallergenic alternative for jewelry, ensuring comfortable wear for everyone.

Explore BioDur® 108 Today

BioDur® 108 represents a significant advancement in stainless steel technology.  Its unique combination of properties makes it a compelling choice for a variety of applications, but especially so for the medical industry. If you're looking for a nickel-free and cobalt-free stainless steel solution for your next project, we invite you to explore more information below or reach out to our team with any questions.