Does Stainless Steel Bolt Have Magnetic Nature?

Stainless steel is a steel comprises of several chemical substances or also called alloy. Those substances are chromium, nickel, ferrum, mangan, silicon, carbon, sulfur, molybdenum, fosfor, and others. The proportion of each chemical element differs depending on the grade of stainless steel. For example, stainless steel grade 304 has a Nickel content of at least 8%, while stainless steel grade 316 has a Nickel content of at least 10%.

There are several common grades of stainless steel, namely:

Why is stainless steel anti-corrosion?

Stainless steel at least contains 10.5% chromium which results in the anti-corrosion. Anti-corrosion can be enhanced by mixing other substances such as nickel, molybdenum, and titanium.

Can stainless steel be corrosive or rusty?

Stainless steel can be still rusty as it is not 100% anti-corrosion. This can be caused by incorrect installation, flawed products, or unsuitable environment for a certain grade of stainless steel.

Does stainless steel have magnetic nature?

Table 1 suggests that there are many types of stainless steel which are ferritic, austenitic, martensitic, and others. The most common grades of stainless steel are grade 304 (SUS304) and 316 (SUS316) classified as austenitic. This type of austenitic material does not have magnetic nature. However, after undergoing the process of becoming bolts, nuts, and the like, a slightly magnetic property can emerge. Cold forming processes such as striking during bolt head formation, thread forming, and cutting can trigger magnetic nature despite not as much as iron. Therefore, it is normal for SUS304 and SUS316 bolts to have a slight magnetic nature.

However, in case you are uncertain about SUS304 and SUS316, as explained, it is chromium and nickel compositions on stainless steel to emerge the magnetic nature. These substances set a vital role in determining the grade of stainless steel. Therefore, magnetic nature is not the basis for determining whether a material is stainless steel or not. This is because there are stainless steels that do not have magnetic nature, but their anti-corrosions are below that of SUS304/SUS316.

The following table explains the elemental composition of each grade of stainless steel based on international standards.

According to the table, it can be observed that Stainless Steel 304 must have a Nickel (Ni) composition above 8% and Chrome (Cr) composition above 18%, while grade 201 only has a Nickel composition of 3.5% and a Chrome composition of 16%. Therefore, grade 201 of stainless steel has lower anti-corrosion compared to grade 304. Multi Baja does not provide grades that are lower than grade 304. Please beware as there are grade 201/202 of stainless steel with relatively cheaper price than grade 304 in the market.

Multi Baja provides Mill certificate to elaborate chemical composition of bolts and it comprises of other details such as tensile strength and physical properties. The mill certificate is the outcome of laboratory tests performed on samples taken from each production batch, to ensure that the products at Multi Baja meet international standards in terms of chemical composition, tensile strength, and dimensions.

In the displayed image, it can be seen that the production batch contains 10.09% Nickel and 18.21% Chromium. These figures meet international standards, as stated in Table 2. This is the key factor to consider when determining if a material is stainless steel.

The instrument used in the manufacturer’s laboratory is called an X-Ray Fluorescence Spectrometer, as shown in Figure 2 below. This device is directed at the item to be tested for its chemical composition, and the material’s chemical content is then immediately displayed.

Multi Baja is an official distributor of THE brand for stainless steel bolts and nuts. CONTACT US for inquiries.