Q:What kinds of stainless steel are magnetic?

Austenitic stainless steel (represented by 304) is non-magnetic, but can also be weakly magnetic, while ferritic stainless steel, such as grades 409, 430, 439, and martensitic (represented by 410) are generally magnetic.

Time：18/02/2025 14:13:56

Austenitic stainless steel is the most widely used stainless steel. It contains about 18% chromium and 8% nickel and belongs to chromium-nickel stainless steel. It has a low carbon content. Due to the addition of nickel, after solidification treatment, its microstructure is single-phase austenite at room temperature, which is usually non-magnetic. However, magnetism may also occur due to fluctuations in chemical composition or different processing conditions caused by smelting. For example, 304 stainless steel will have a small amount of martensite or ferrite structure due to component segregation or improper heat treatment during smelting. In this way, it will have weak magnetism.

Martensitic stainless steel belongs to chromium stainless steel. It has a high carbon content. After heat treatment, its mechanical properties can be significantly adjusted. Therefore, this type of steel is generally used after quenching and tempering. At room temperature, its microstructure is tempered martensite with strong ferromagnetism, such as 1Cr13, 2Cr13, 3Cr13, 4Cr13, 7Cr13, etc.

Ferritic stainless steel also belongs to chromium stainless steel. Its chromium content is generally greater than 11.5%. At room temperature, its microstructure is a single-phase ferrite structure. Even if the steel is heated from room temperature to high temperature (900~1100℃), its structure will not change significantly. This type of steel also has strong ferromagnetism, and representative grades include 430, etc.

Stainless steel can be divided into several categories according to its organizational structure at room temperature:
1. Austenite type: such as 304, 321, 316, 310, etc.;
2. Martensite or ferrite type: such as 430, 420, 410, etc.;
Austenite is non-magnetic or weakly magnetic, and martensite or ferrite is magnetic.

Time：17/02/2025 12:55:26