What are the medical applications of stainless steel?
Did you know that stainless steel sheets are widely used in the medical industry? In fact, you can find many products made of this metal in hospitals and clinics – do you know the reason for this?
To do so, you must first learn more about what 304 and 316 stainless steel are and the great advantages they bring.
Introduction
Grades of stainless steel for medical applications
The design and manufacture of medical products presents some of the industry’s most difficult problems to overcome. By their very nature, devices designed for medical use must meet extremely high design and manufacturing standards.
In a world increasingly concerned with litigation and medical malpractice claims, any item that comes into contact with the human body must function perfectly.
With such a wide range of applications, medical devices come in all shapes and sizes to do a multitude of jobs, so scientists and engineers use a variety of materials to meet the most stringent design specifications.
This is where stainless steel comes into play: it is one of the most commonly used materials for the manufacture of medical equipment, in particular austenitic stainless steel 304.
Grade 304 stainless steel
304 stainless steel is considered by the world to be one of the most suitable materials for the manufacture of medical equipment. In fact, it is the most commonly used stainless steel in the world today.
No other grade of stainless steel is available in so many shapes, finishes and for such a variety of applications. Because of its properties, it offers unique characteristics at a competitive price, making it a logical choice for medical equipment specifications.
Typical chemical composition of 304 stainless steel for medical equipment
Table 1. Typical chemical composition of 304 stainless steel
| Composition | C | Mn | Si | P | S | Cr | Ni | N |
| 0.07max | 2.0 max | 0.75 max | 0.045 max | 0.015 max | 18.0 – 19.5 | 8.0 – 10.5 | 0.10 max |
The guarantee that equipment will not react chemically with body tissues, the cleaning agents used for sterilisation and the heavy and repeated use they suffer from means that 304 stainless steel is the perfect material for hospitals, surgical and nursing staff.
Typical mechanical properties of 304 stainless steel for medical equipment
Table 2. Mechanical properties of 304 stainless steel
| Grade | Tensile | Flexibility criteria | Elongation | HRB Max | HB Max |
| 304 | 540 | 250 | 45 | 92 | 201 |
The hardness of 304 stainless steel is not its only advantage. This metal is also extremely machinable, capable of being formed without remelting. It is perfect for the manufacture of bowls, spouts, frying pans and other medical containers.
There are several variants of 304 stainless steel with enhanced properties for specific applications, such as 304L, a low carbon version, used in high specification situations requiring high strength welding.
Certain medical equipment may contain 304L, where the welds must withstand high impact, prolonged pressure, etc. This grade is also considered a low temperature steel, which means it can be used in applications where it must work at extremely low temperatures.
In corrosive environments, Grade 304L also offers a higher resistance to intergranular corrosion than other similar stainless steels. The combination of low yield strength and high elongation potential means that 304 stainless steel is suitable for forming into complex shapes without the need for baking.
If medical applications require a harder or stronger steel, this metal can be cold worked. In the annealed state, 304 and 304L can be very ductile and can be easily formed, bent, or fabricated. However, they harden quickly and may require additional heating to improve ductility.
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Medical uses of stainless steel 304
Stainless steel 304 is used in a wide range of different types of industrial and domestic applications. In the medical industry, 304 is the material of choice for its high corrosion resistance, malleability, strength, precision in manufacturing, reliability and hygiene.
The quality of 304 stainless steel offers many advantages.
The cost of the material is reduced because it can be used for all types of medical applications.
Rust resistance. The risk of infection due to rust and other surface defects is reduced.
·Highly resistant to corrosion
·Recyclable
·Highly resistant to bacteria
·Will not be contaminated. Can be cleaned and reused many times in the medical field.
·Non-magnetic. Ideal for handling implants in the body
·High heat resistance
·Once hardened, 304 stainless steel will retain its shape
·Surgical stainless steel
For surgical stainless steel, specific grades of stainless steel such as 316 and 316L are used. these alloys are formed from elements such as chromium, nickel and molybdenum and offer unique qualities to materials scientists and surgeons.
Chromium: increases the material’s resistance to scratching and corrosion. Perfect for resisting medical cleaning and sterilisation.
Nickel. Provides an extremely smooth and polishable surface, a detail required for precision machining. Also important for hygiene.
Molybdenum. Provides hardness after forming and is excellent for sharp edges (scalpels).
Note: In some cases, the immune system shows an adverse reaction to the nickel content in some stainless steels (both skin and systemic).
In these cases, titanium can be used instead of stainless steel; however, this is a more expensive solution. Typically, stainless steel is used for temporary implants, while titanium is used for permanent and more expensive implants.
The list below includes some possible medical uses for stainless steel.
Precision tubes
Orthopaedic implants (316 / 316L)
Artificial heart valves (316 / 316L)
Bone fixation
Mandrel presses
Chemical and hazardous waste containers
·Steel wire
·Steel wire spools
·Specialised guide wires
·Tweezers
·Screws/prostheses/plates
·Medical needles
·Medical syringes
·Sensor probes
·Catheters
·Ear, nose and throat masks
·Hand basins/bowls/surfaces/trays/knives
In conclusion, both 304 and 316 stainless steels are ideal for the medical industry as they have excellent characteristics that allow the hygiene sector to respect the standards of cleanliness and sterilisation.
At Tisco steel, you will find a range of stainless steel products in different grades. If you have any questions about our plates, tubes, fittings, bars and angles, please do not hesitate to contact us via our form.