Stainless steel is carbon steel containing chromium, enabling it to resist corrosion. The chromium contained in the stainless steel leads to the formation of a chromium oxide film on the steel’s surface. This property can best be displayed by the stainless steel pipe, which is corrosion-resistant due to the presence of chromium.
The film is important because it protects the steel from chemical or mechanical damage. This can be discovered chiefly when looking at the stainless steel pipe. The corrosion resistance of steel can be increased by involving elements such as Nickel, nitrogen, and molybdenum.
Table of Contents
Classification of Stainless Steel
Stainless steel can be classified into five groups: martensitic, ferritic, austenitic, duplex, and precipitation-Hardening.
Martensitic
Martensitic Stainless Steel is corrosion resistant and hardenable 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 corrosion-free environments or settings that do not experience too much pollution. This product can be used in parts that need to be corrosion-resistant and robust.
ii. Type 410S
This contains a lower content of carbon compared to Type 410. It helps in improving welding processes because it is not very hard. It also can resist heat temperatures.
iii. Type 414
It contains a high content of Nickel to improve corrosion resistance. 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 a high chromium content that helps increase corrosion resistance. This can be used in pumps and valves that require robust equipment.
vii. Type 440
It has an increased carbon and chromium content for toughness and high corrosion resistance. It can be used in surgical instruments.
2. Ferritic
This group of stainless steel helps resist oxidation, stress, cracking, and corrosion. They are magnetic, and heat cannot be used to harden them. 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 exhaust. They are divided into the following grades:
i. Type 430
This grade type has less corrosion but high resistance to corrosives such as sulfur gases, organic acids, and nitric acid.
ii. Type 405
This has a lower chromium content but an additional aluminium element. 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 corrosion resistance. This can be used in fasteners or automotive trims.
v. Type 436
This type has additional columbium content that helps heat and corrosion resistance. It is commonly used in parts of deep-drawn.
vi. Type 446
Higher chromium content has been added to improve resistance to scaling and corrosion.
3. Austenitic
This group of stainless steel has a high content of Nickel and chromium. These contents are suitable 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 nickel and chromium content, making it possible to manufacture 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 materials. They are adamant 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 higher corrosion resistance. 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 points discussed above, you can conclude that stainless steel equipment is the best as it has unparalleled benefits compared to conventional steel.