What is Stainless Steel?
Many of us are already familiar with stainless steel as we can find it anywhere near us. Stainless steel is used in various industries, including construction, healthcare, and food processing. Its resistance to corrosion is the key reason for its massive use.
We may be familiar with stainless steel but lack of knowledge what it really is. In order to understand it, let’s take a look at the definition, characteristics, and classification of stainless steel.
Definition
Stainless steel is steel alloy that consists of a certain amount of chromium and carbon. It is most notable for its resistance to rust, staining, and corrosion than regular steel. Due to its resistance to corrosion, stainless steel is often found as materials in construction, surgical tools, cutlery, cookware, and many more.
Classification
In general, there are five types of stainless steels which are differentiated by grades, including:
- Austenitic Stainless Steel – Stainless steel grade 200 and 300 series. Its main characteristics are resistant to corrosion, non-magnetic, formable, and can only be hardened by cold working. There are three subtypes of austenitic stainless steel: straight, L, and H.
- Ferritic Stainless Steel – Stainless steel grade 400 series with the main characteristics of low resistant to corrosion, magnetic, and can be hardened by cold working.
- Martensitic Stainless Steel – Stainless steel grade 400 and 500 series with the characteristics of resistant to hot temperature, magnetic, strong, and has a medium resistant to corrosion.
- Precipitation Hardening Grade – Stainless steel grade PH with the characteristics of highly resistant to corrosion and hot temperature, magnetic, and solid.
- Duplex – A mixture of austenitic and ferritic stainless steel with the characteristics of highly resistant to corrosion, strong, and solid.
Characteristics
As one of the metal products, stainless steel has certain characteristics, such as:
- Resistant to corrosion
The amount of chromium in stainless steel affects its resistance. The more the amount is the more resistant it is to corrosion, rust, and stain. Normally, the minimum percentage of chromium in stainless steel is 10.5%, playing the role as the main protector. On the other hand, the other element, carbon, is resistant to O2 and has self-healing characteristic, making it undamaged once it gets cut.
- Resistant to hot temperature
Stainless steel is resistant to hot temperature, especially the austenitic one. The high amount of chromium causing it able to protect itself from the hot temperature that leaves it undamaged. The higher the percentage of chromium is, the more resistant it is to the elevated temperature.
- Resistant to low temperature
Stainless steel, especially the austenitic one is resistant to both high and low temperature. It has higher cryogenic resistance at low temperature unlike the other stainless steels, such as martensitic, ferritic, and precipitation hardening steels.
- Magnetic and non-magnetic
Some stainless steels are magnetic and some not, depending on the content. Some stainless steels is made magnetic with the help of cold working and it works. However, it’s not always working for all types of stainless steels, especially nickel grades 310 and 316.