Is Surgical Steel Magnetic?


Surgical steel is a type of stainless steel used in biomedical applications. There is no formal definition of what constitutes surgical steel, so manufacturers usually apply the term to any grade of corrosion-resistant steel. 

Have you ever wondered if surgical steel is magnetic? In this article, we are going to discuss just that. We will look at the properties of surgical steel. Then we will talk about its different types and their magnetism. We will also discuss their resistance and potentially allergic nature.

Read: Is Carbon Steel Magnetic? (Yes. It is)

What is Surgical Steel?

Surgical steel is a type of steel commonly used in medical equipment, such as surgical instruments and implants. There are various types of surgical steel, and they are made up of different elements, such as chromium, nickel, molybdenum, etc.

Surgical steel is typically composed of iron, carbon, chromium, and nickel, with smaller amounts of other metals such as molybdenum, vanadium, etc. Hygiene and sterility are critical for medical settings, so it is necessary to use corrosion-resistant products. 

Since stainless steel is highly resistant to corrosion and rust, it is ideal for this purpose. Surgical steel is also durable. Besides being strong, it can withstand repeated sterilizations without getting damaged or losing its properties. 

Another key feature of surgical steel is its biocompatibility: it is well-tolerated by the body and does not cause adverse reactions. This is particularly important for medical implants, as the release of particles can cause local tissue damage, inflammation, or systemic toxicity.

The most common surgical steels are austenitic SAE 316 stainless and martensitic SAE 440  & 420 stainless steels.

Is Surgical Stainless Steel Magnetic?

Yes, surgical stainless steel can be magnetic depending on its composition. The term surgical steel is not a specific type of steel but a general word used to refer to commonly used medical instruments, and these may or may not be magnetic.

Let us first understand what magnetism is. Magnetism is a force caused by the motion of electric charges. Every substance is made up of atoms. These atoms have electrons (particles that carry an electric charge) that circle the atom’s center, called the nucleus.

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In most substances, equal numbers of electrons spin in opposite directions. This cancels out their magnetism, and they are not attracted to a magnetic field. These include things like cloth, wood, paper, etc., and are called diamagnetic.

However, in some substances like iron, the electrons spin in the same direction. This allows their magnetic fields to combine, and it produces a magnetic field extending beyond the atoms. These objects are strongly attracted to magnets and are called ferromagnetic. 

Now, most types of stainless steel are non-magnetic because they contain a high percentage of chromium and nickel, which are non-magnetic metals. However, some stainless steels contain a high level of iron in their composition, which is a ferromagnetic material and can make the steel magnetic.

In the case of surgical steels also, the magnetism will depend on the composition. Some surgical steels are magnetic while others are not, as will discuss below.

What Types of Surgical Stainless Steel are Magnetic?

Surgical stainless steel may or may not be magnetic depending on its composition. There are various types of surgical steel: ferritic and martensitic surgical steels are magnetic while austenitic surgical steels are non-magnetic.

Ferritic and martensitic surgical steels have a body-centered cubic crystal structure. This causes their electrons to align in a way that produces a magnetic field. Moreover, the presence of iron, carbon, and other magnetic elements in them also contributes to their magnetism.

Therefore, ferritic and martensitic are magnetic. On the other hand, austenitic steels have a face-centered cubic crystal structure, which doesn’t allow for the alignment of their electrons. Moreover, they also contain higher levels of chromium and nickel, which are non-magnetic.

So, austenitic steels surgical steels are non-magnetic. 


Does Surgical Steel Rust?

No. Surgical steel is a type of stainless steel that is highly resistant to rust and corrosion. This is because of its high levels of chromium and nickel, which act as a protective barrier for the steel. However, even surgical steel is not completely immune to nature.

Surgical steel contains a high percentage of chromium and nickel. These form a passive oxide layer on the surface of the steel, which acts as a protective barrier. It does not let the underlying steel get exposed and therefore protects it from rust and corrosion.

The corrosion resistance of stainless steel is crucial for making medical equipment because hygiene and cleanliness are critical in such settings. Because of its resistance, surgical steel can also resist getting sterilized repeatedly without getting damaged and last longer.

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However, even surgical steel is not completely immune to corrosive processes. If exposed to extremely harsh environments and not maintained properly, it can still get damaged over time. Therefore, it is necessary to properly care for medical instruments to ensure their longevity. 

Is Surgical Steel Hypoallergenic?

Yes, surgical steel is hypoallergenic, meaning that it is unlikely to cause an allergic reaction in most people. This is because surgical steel is developed with elements that make it biocompatible and non-reactive to the human body.

Chromium and nickel, the major constituents of surgical steel, are non-toxic and non-reactive elements. So, surgical steel also does not cause a negative reaction in most people. This (along with other reasons like resistance) is why it is widely used in medical and surgical instruments. 

However, some individuals may still be sensitive to some of the components of the steel, say nickel. In such cases, they can use steel products that are designed with low nickel content or go for alternative materials. 

Read: Is Galvanized Steel Magnetic? (Yes. It is)

Difference Between Stainless Steel and Surgical Steel

Stainless steel and surgical steel are both types of steel that are highly resistant to corrosion. However, there are differences between the two. Stainless steel is a general term used for steels having a certain level of chromium, while surgical steel is a type of stainless steel.

Stainless steel is an alloy of iron that contains at least 11% chromium. Carbon, metals, and non-metals are also included to obtain the desired properties. The chromium forms a protective oxide layer on the surface of the steel, which prevents it from rusting and corrosion.

Surgical steel, in contrast, is a type of stainless steel. Besides being corrosion-resistant, is also designed to be non-reactive and biocompatible with the human body. It usually includes high levels of nickel and chromium, which are non-toxic and non-reactive.

Stainless steel is used in a wide variety of applications, such as kitchen appliances, industrial machinery, architecture, etc. On the other hand, surgical steel is mainly used for medical equipment and implants, thanks to its biocompatibility.

Properties of Surgical Steel

  1. Biocompatible: Biocompatibility refers to the ability of a material to interact with living tissue without causing any adverse effects. Surgical steel is highly biocompatible, so it is well-tolerated by the body and does not cause any negative reactions. It is biocompatible for three reasons. First, it is inert, meaning that it does not react with the body’s tissues or fluids. Second, it is hypoallergenic, so it does not cause an allergy. Finally, surgical steel is also corrosion-resistant, so it is unlikely to degrade & release harmful chemicals. 
  1. Durable: Surgical steel is known for its durability and resistance to damage. It is a relatively hard material, which makes it less susceptible to scratches, dents, or other forms of damage. For medical devices, this is a crucial feature as they must maintain their shape and function over time. Medical equipment is also repeatedly sterilized, and surgical steel can withstand them without becoming damaged or losing its properties.
  2. Corrosion-Resistance: In medical settings, instruments and implants must face harsh environments and repeated sterilization, so it is necessary for them to be resistant. The high level of chromium content in surgical steel achieves just this. It forms a protective layer on the surface of the steel when exposed to oxygen, thereby preventing it from further oxidation & rusting. This property of surgical steel is crucial for medical implants.
  3. Cleanability: When metals come in contact with substances such as blood, saline solutions, or cleaning agents, they tend to get discolored or stained. However, this does not happen with surgical steel, thanks to its smooth, non-porous surface. This surface does not have any cracks (that can trap contaminants), which is why surgical steel is quite easy to clean and sterilize. The ease of cleanability helps in preventing infection and ensuring the safety of patients as well as medical workers.
  1. Cost & Workability: Surgical steel is usually preferred over other metals such as titanium or ceramics because it is less expensive. It is also readily available. Moreover, surgical steel is a relatively easy material to work with, so it can be shaped and formed into various forms and sizes. This makes it ideal for a wide range of medical applications, from surgical instruments to implants.
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In this article, we have discussed the magnetism of surgical steel. We looked at the properties of surgical steel, such as its corrosion resistance and biocompatibility, which make it ideal for medical equipment and implants. We also discussed the different types of surgical steel, whose composition determines their magnetism. 

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