All You Need to Know about Different Grades of Stainless Steel

Stainless Steel

Stainless steel is carbon steel that contains chromium which enables it to resist corrosion. This property can best be displayed by the stainless steel pipe which is corrosion resistant due to the presence of chromium. The chromium contained in the stainless steel leads to the formation of a film of chromium oxide on the surface of the steel.

The film is important because it protects the steel from chemical or mechanical damage. This can be discovered mostly when you take a look at the stainless steel pipe. The corrosion resistance of steel can be increased by involving additional elements that include nickel, nitrogen, and molybdenum.

Classification of Stainless Steel

Stainless steel can be classified into 5 groups that comprise of martensitic, ferritic, austenitic, duplex, and precipitation-Hardening.

Martensitic

Martensitic Stainless Steel is corrosion resistant as well as harden-able by exposing them to high heat temperatures. They are chromium steels that have no nickel present. These types of steel are commonly used in cases where strength, wear resistance, and hardness are required. Martensitic stainless steel is divided into several grades that include:

i. Type 410

This contains a lower content of the alloy. It is cheap and can be treated by exposure to heat. This grade type is commonly used in environments that are corrosion free or environments that do not experience too much corrosion. This product can be used in parts that need to be corrosion resistant and strong.

ii. Type 410S

This contains a lower content of carbon compared to Type 410. It helps in improving welding processes because it not very hard. It also can resist heat temperatures.

iii. Type 414

It contains a high content of Nickel to improve resistance to corrosion. It can be used in cutlery or springs.

iv. Type 416

It contains elements such as sulfur and phosphorus that improves machinability. It can be used in parts of the screw machine.

v. Type 420

Its increased content of carbon improves mechanical properties. This can be used in surgical instruments.

vi. Type 431

It contains an increased content of chromium that helps to increase resistance to corrosion. This can be used in pumps and valves that require strong equipment.

vii. Type 440

Has increased content of carbon and chromium for toughness and high resistance to corrosion. It can be used in surgical instruments.

2. Ferritic 

This group of stainless steel is useful in the resistance of oxidation, stress, cracking, and corrosion. They are magnetic and heat cannot be used to harden it. Also, they have high corrosion resistance properties. No nickel is present in this type of stainless steel. They are commonly used for decorating sinks and automotive systems like the exhaust. They are divided into the following grades:

i. Type 430

This grade type has a less corrosion property but high resistance property to corrosives such as sulfur gases, organic acids, and nitric acid.

ii. Type 405

This has a lower content of chromium but has an additional element of aluminum. It is commonly used in heat exchangers.

iii. Type 409

It is very cheap since it has a lower content of chromium. Commonly used in muffler stock.

iv. Type 434

It has an increased content of molybdenum that increases resistance to corrosion. This can be used in fasteners or automotive trims.

v. Type 436

This type has additional content of columbium that helps in the heat and corrosion resistance. It is commonly used in parts of deep-drawn.

vi. Type 446

Higher content of chromium has been added to improve resistance on scaling and corrosion.

3. Austenitic 

This group of stainless steel has a high content of nickel and chromium. These contents are good for mechanical properties and corrosion resistance. Heat treatment cannot be used in the hardening of this group of stainless steel. Divided into the following grades:

i. Type 406

It has a high content of nickel and chromium which makes it possible in the manufacture of processing equipment.

ii. Type 316

This grade type has a combination of nickel, molybdenum, and chromium. This helps in preventing corrosion.

4. Duplex

This group is a combination of ferritic and austenitic material. They are very tough and ductile. They are highly resistant to corrosion. They are divided into the following grades:

i. Type 2205

This type is essential in highly corrosive environments.

ii. Type 2304

This has a higher resistance to corrosion. It is commonly used in welding and very simple to fabricate.

5. Precipitation Hardening

This group can be hardened and strengthened by the use of heat. It provides designers with a distinctive combination of strength, corrosion resistance, and fabricability.

With all the discussed points above, you can conclude that stainless steel equipment is the best as it comes with unparalleled benefits in comparison to conventional steel.