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What stainless steel is used in medical devices?
2026-04-15
The use of medical devices is a crucial aspect of medicine, making the selection of appropriate stainless steel materials paramount. Using the wrong material can lead to serious risks and equipment malfunctions, resulting in a series of safety issues, high repair costs, and jeopardizing patient safety. FRIMA is a precision CNC machining service provider, offering CNC machined parts and components. We have over ten years of experience machining medical-grade stainless steel. Below, I will guide you through common types of medical stainless steel machining to help you make safe and effective choices for your medical device components.
Which type of stainless steel is commonly used in medical devices?
There are many types of stainless steel commonly used, including 316L, 304, 420, 440, and 17-4 PH. For many medical devices, 316 or 316L stainless steel is often the best choice. It has excellent corrosion resistance and can withstand high-temperature sterilization. This makes it an ideal material for surgical instruments and implants.
Introduction to common medical stainless steel
Austenitic Stainless Steels
● 316 & 316L
Among the most commonly utilized austenitic stainless steels, the “L” designation signifies low carbon content, which effectively enhances corrosion resistance following welding operations. These grades deliver exceptional corrosion resistance, favorable formability, and reliable biocompatibility.
They are extensively applied in medical implants such as bone screws and plates meeting ASTM F138/F139 standards, surgical instruments including scalpels and forceps, as well as hypodermic needles. A key advantage is their strong resistance to bodily fluids and clinical cleaning agents. Based on practical experience, 316L is frequently selected by clients for components requiring superior corrosion resistance and biocompatibility.
● 304
Also widely employed and often referred to as 18-8 stainless steel, 304 provides decent corrosion resistance, though typically inferior to 316—particularly against chloride-induced pitting corrosion such as in saline environments.
It is commonly used for hospital apparatus, instrument trays, and certain non-critical surgical tools. As noted, it also enjoys widespread use in the food processing industry.
Martensitic Stainless Steels
● 420 & 440 Series (e.g., 440C)
These steels are heat-treatable for high hardening, resulting in excellent strength and wear resistance.
They are perfectly suited for cutting instruments including surgical blades, dental tools, and scissors that demand a sharp, long-lasting cutting edge. Corrosion resistance for this series is lower compared to 300-series austenitic stainless steels.
Precipitation-Hardening Stainless Steels
● 17-4 PH
This grade balances high strength, hardness, and reliable corrosion resistance effectively. It can be heat-treated to attain various strength grades, making it suitable for surgical instruments and devices that require high structural strength along with moderate corrosion resistance.
● 316 & 316L
Among the most commonly utilized austenitic stainless steels, the “L” designation signifies low carbon content, which effectively enhances corrosion resistance following welding operations. These grades deliver exceptional corrosion resistance, favorable formability, and reliable biocompatibility.
They are extensively applied in medical implants such as bone screws and plates meeting ASTM F138/F139 standards, surgical instruments including scalpels and forceps, as well as hypodermic needles. A key advantage is their strong resistance to bodily fluids and clinical cleaning agents. Based on practical experience, 316L is frequently selected by clients for components requiring superior corrosion resistance and biocompatibility.
● 304
Also widely employed and often referred to as 18-8 stainless steel, 304 provides decent corrosion resistance, though typically inferior to 316—particularly against chloride-induced pitting corrosion such as in saline environments.
It is commonly used for hospital apparatus, instrument trays, and certain non-critical surgical tools. As noted, it also enjoys widespread use in the food processing industry.
Martensitic Stainless Steels
● 420 & 440 Series (e.g., 440C)
These steels are heat-treatable for high hardening, resulting in excellent strength and wear resistance.
They are perfectly suited for cutting instruments including surgical blades, dental tools, and scissors that demand a sharp, long-lasting cutting edge. Corrosion resistance for this series is lower compared to 300-series austenitic stainless steels.
Precipitation-Hardening Stainless Steels
● 17-4 PH
This grade balances high strength, hardness, and reliable corrosion resistance effectively. It can be heat-treated to attain various strength grades, making it suitable for surgical instruments and devices that require high structural strength along with moderate corrosion resistance.
Which type of medical-grade stainless steel is the best?
In reality, there is no definitive "best" choice, as it largely depends on the specific application it will serve. However, 316 stainless steel, especially 316L stainless steel, is generally considered the preferred choice, particularly for implants and devices that come into contact with bodily fluids or tissues.
316L stainless steel has many advantages:
● Outstanding Biocompatibility: 316L boasts a well-established track record in medical device applications, demonstrating excellent tissue compatibility with the human body and effectively lowering the likelihood of adverse biological responses.
● Exceptional Corrosion Protection: Compared with 304 stainless steel, the inclusion of molybdenum greatly boosts its resistance to pitting and crevice corrosion, particularly in chloride-rich physiological environments inside the human body. This is vital for long-term implant performance and instruments subjected to frequent reuse.
● Reliable Sterilization Stability: This material maintains stable performance under routine medical sterilization processes such as autoclaving (high-temperature steam) and gamma irradiation, with no notable material degradation occurring.
● Balanced Mechanical Properties: 316L delivers an ideal combination of mechanical strength and formability, enabling it to be fabricated into intricate, complex components while retaining sufficient structural rigidity.
Special circumstances:
● If very high strength is the primary requirement, then 17-4 PH might be an option.
● If extremely high hardness and sharpness retention are needed (e.g., for surgical blades), then martensitic steel like 440C might be better.
● For less critical applications where cost is a major factor and corrosion resistance is less critical, 304 might be sufficient.
316L stainless steel has many advantages:
● Outstanding Biocompatibility: 316L boasts a well-established track record in medical device applications, demonstrating excellent tissue compatibility with the human body and effectively lowering the likelihood of adverse biological responses.
● Exceptional Corrosion Protection: Compared with 304 stainless steel, the inclusion of molybdenum greatly boosts its resistance to pitting and crevice corrosion, particularly in chloride-rich physiological environments inside the human body. This is vital for long-term implant performance and instruments subjected to frequent reuse.
● Reliable Sterilization Stability: This material maintains stable performance under routine medical sterilization processes such as autoclaving (high-temperature steam) and gamma irradiation, with no notable material degradation occurring.
● Balanced Mechanical Properties: 316L delivers an ideal combination of mechanical strength and formability, enabling it to be fabricated into intricate, complex components while retaining sufficient structural rigidity.
Special circumstances:
● If very high strength is the primary requirement, then 17-4 PH might be an option.
● If extremely high hardness and sharpness retention are needed (e.g., for surgical blades), then martensitic steel like 440C might be better.
● For less critical applications where cost is a major factor and corrosion resistance is less critical, 304 might be sufficient.
Is 316 stainless steel medical grade?
Yes, 316 stainless steel, especially the low-carbon version 316L, is widely recognized and used as a medical-grade material. It meets the stringent requirements of many medical and surgical applications, including implants.
Chemical Composition
316 stainless steel consists of chromium, which provides fundamental corrosion resistance, nickel to enhance formability and corrosion performance, and critically, molybdenum. This element greatly improves resistance to pitting and crevice corrosion, making the alloy highly suitable for exposure to chloride-containing bodily fluids.
The 'L' in 316L
The letter 'L' stands for low carbon, with a typical carbon content of less than 0.03%. Reducing carbon helps minimize harmful carbide precipitation during welding, a phenomenon that can weaken corrosion resistance along weld joints. Because many medical devices require welding and operate in corrosive environments, 316L is commonly preferred over conventional 316 for critical applications, especially surgical implants.
Biocompatibility
Decades of clinical application have proven that 316L is generally well-tolerated by the human body, rarely causing adverse reactions when implanted or in contact with biological tissues.
Compliance with Standards
Medical-grade 316L typically conforms to strict industry specifications such as ASTM F138, ASTM F139, and ISO 5832-1. These standards establish precise requirements for chemical composition, mechanical properties, and microstructure to ensure reliable performance in surgical applications.
Chemical Composition
316 stainless steel consists of chromium, which provides fundamental corrosion resistance, nickel to enhance formability and corrosion performance, and critically, molybdenum. This element greatly improves resistance to pitting and crevice corrosion, making the alloy highly suitable for exposure to chloride-containing bodily fluids.
The 'L' in 316L
The letter 'L' stands for low carbon, with a typical carbon content of less than 0.03%. Reducing carbon helps minimize harmful carbide precipitation during welding, a phenomenon that can weaken corrosion resistance along weld joints. Because many medical devices require welding and operate in corrosive environments, 316L is commonly preferred over conventional 316 for critical applications, especially surgical implants.
Biocompatibility
Decades of clinical application have proven that 316L is generally well-tolerated by the human body, rarely causing adverse reactions when implanted or in contact with biological tissues.
Compliance with Standards
Medical-grade 316L typically conforms to strict industry specifications such as ASTM F138, ASTM F139, and ISO 5832-1. These standards establish precise requirements for chemical composition, mechanical properties, and microstructure to ensure reliable performance in surgical applications.
Conclusion
As a leader in precision CNC machining and custom medical parts manufacturing, FRIMA specializes in CNC milling, CNC turning, and 5-axis machining of 316/316L stainless steel components. Combining advanced CNC manufacturing capabilities with strict adherence to ASTM F138 and ISO 5832-1 standards, we deliver high-precision, biocompatible parts for surgical implants, medical instruments, and critical healthcare applications. Our expertise in medical-grade CNC machining ensures superior corrosion resistance, mechanical performance, and consistent quality for global medical device OEMs. Contact us be free, our email: info@frimaparts.com.