What is Martensitic Stainless Steel?

Martensitic stainless steel is a kind of stainless steel, which has the characteristics of high strength, high hardness and wear resistance. It is named for the martensitic crystal structure that forms when steel is quenched from high temperatures. Martensitic stainless steel is a kind of stainless steel whose properties are adjusted by quenching and tempering through heat treatment process. The final body structure is mainly martensite. Martensitic stainless steel is a kind of hardenable stainless steel. This type of stainless steel has two Basic conditions, one is that there must be an austenite phase region in the equilibrium phase diagram, and the other is that the chromium content must be above 10.5%, so that the alloy forms a corrosion-resistant passivation film.

Passivation treatment of martensitic stainless steel

Martensitic stainless steel is also called stainless iron, and the common grades generally used for blade screws are SUS410, 420, 430, etc.

Standard 1Cr13, 2Cr13, 3Cr13, 1Cr17 and so on. Due to the chromium content of stainless iron materials is about 13%, it is more expensive than austenitic stainless steel Q

For example, 304 has a low chromium content of 18% and almost no nickel, so the anti-rust performance is much worse than that of 304 stainless steel. This leads to

As a result, stainless iron products are easy to rust without anti-rust treatment after processing, and they cannot pass corrosion resistance tests such as salt spray tests.

tried. Therefore, in general, after the stainless iron products are processed, passivation and anti-rust treatment is required, and the treatment process is relatively simple.

Passivation treatment process:

Pretreatment (degreasing and cleaning)→water washing→passivation treatment→water washing→passivation film strengthening treatment→water washing→drying treatment

Generally, after passivation treatment, the corrosion resistance can be greatly improved, and the salt spray test can be improved by at least 20 times;

There are tests for 48, 96, 168 hours, etc., and the corrosion resistance is slightly different mainly according to different materials and processing techniques.

What are the basic characteristics of martensitic stainless steel?

Martensitic stainless steel is a type of stainless steel known for its high strength, high hardness and corrosion resistance. It has a relatively high carbon content, so it can be heat treated to harden and strengthen the structure. The following are some basic properties of martensitic stainless steel:

High Strength: Martensitic stainless steel has high tensile and yield strengths, making it a strong and durable material for a variety of applications.

Hardness: Martensitic stainless steel can be heat-treated to achieve high hardness, which makes it suitable for applications requiring wear resistance and durability.

Corrosion resistance: Martensitic stainless steel has good corrosion resistance, especially in mild environments. However, it is not as corrosion resistant as austenitic stainless steel.

Magnetic: Martensitic stainless steel is magnetic, which allows it to be used in applications that require magnetism, such as electric motors and transformers.

Poor weldability: Due to the high carbon content of martensitic stainless steel, it is easy to crack during welding and has poor weldability.

Low formability: Martensitic stainless steels have low formability and are difficult to form into complex shapes and designs.

Martensitic stainless steel is a strong, hard and corrosion-resistant material used in a variety of applications requiring high strength and wear resistance. Its magnetic properties and poor weldability make it suitable for some specialized applications, while its low formability limits its use in other applications.

Can martensitic stainless steel be work hardened?

 Work hardening, also known as cold working, is the process by which a material undergoes plastic deformation at room temperature. Plastic deformation causes dislocations in the crystal structure of the material, increasing its hardness and strength.

Martensitic stainless steel is particularly suitable for work hardening because it has a high carbon content and can be heat treated to obtain a hardened structure. The process of work hardening can further increase its strength and hardness, making it suitable for applications requiring high wear resistance and durability.

However, it is important to note that excessive work hardening can cause the material to become brittle and prone to cracking. Therefore, it is important to carefully control the amount and rate of work hardening to avoid damage to the material. In addition, martensitic stainless steels have low formability and therefore may not be suitable for applications requiring complex forming or shaping.

Can martensitic stainless steel withstand high temperature?

Martensitic stainless steels are often heat treated to obtain a hardened and strengthened structure, which can make them more resistant to high temperatures. The high carbon content in martensitic stainless steels also contributes to its high-temperature strength.

However, martensitic stainless steels are not as heat resistant as austenitic stainless steels, which have a higher chromium content and are able to maintain their strength and corrosion resistance at higher temperatures. Martensitic stainless steels lose strength and toughness at elevated temperatures, especially above 800°C (1470°F), and may be prone to cracking under thermal stress.

Therefore, the use of martensitic stainless steels in high-temperature applications should be carefully evaluated, and alternative materials such as nickel-based alloys or austenitic stainless steels may be better suited for applications requiring high-temperature strength and corrosion resistance.

Are martensitic stainless steels magnetic?

Yes, martensitic stainless steels are generally magnetic. This is because martensitic stainless steels contain higher levels of carbon and lower levels of nickel than austenitic stainless steels, which makes them more susceptible to magnetism.

When the carbon content in martensitic stainless steel is high enough, the steel can form a magnetic body-centered tetragonal crystal structure. This structure is different from the face-centered cubic structure in non-magnetic austenitic stainless steels.

However, the magnetic properties of martensitic stainless steels vary depending on factors such as the specific alloy composition, level of cold working or heat treatment, and temperature. For example, if a martensitic stainless steel is heat treated above its critical temperature, it loses its magnetism and becomes nonmagnetic. Additionally, martensitic stainless steels can improve their magnetic properties if they are cold worked or strain hardened.

What are the uses of martensitic stainless steel?

Martensitic stainless steel has an obvious phase transition point, which is the rapid cooling transformation from high temperature austenite state to martensite structure. and it contains

High chromium, good hardenability, its strength and toughness can be adjusted in a wide range during tempering, therefore, martensitic stainless steel can be

It can be used as structural steel or tool steel, and is widely used in shipbuilding, industrial and medical industries.

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