Stainless steel is popularly known for its strength and corrosion resistance properties which make it suitable for use in numerous industrial, manufacturing, and construction applications. If you are new to the stainless steel fabrication industry, you may have heard that there is a diverse range of stainless steel grades which fall under the following groups:
- Austenitic stainless steels
- Ferritic stainless steels
- Duplex stainless steels
- Martensitic stainless steels
Before going for a particular grade, it is essential to analyze various factors regarding the intended application to ensure that you choose the most suitable stainless steel grade. Here are some of the key factors that you should have in mind.
Not all grades of stainless steel are weldable. Some grades experience hot cracking, intergranular corrosion, and stress corrosion cracking. If your application requires stainless steel to be welded, you need to choose grades that are weldable. They include stainless steels in the austenitic, ferritic, and duplex groups. Also, any stainless steel grades with low carbon levels are readily weldable. Note that extra care should be taken when welding stainless steel to ensure that the mechanical properties of the metal are not compromised during the welding process.
Some stainless steel applications require heat treatment to harden the metal. However, not all grades of stainless steel harden with heat treatment. For example, austenitic steels don't harden with heat treatment, but martensitic and ferritic stainless steels harden with heat treatment. You should consider choosing these grades you intend to subject the steel to heat treatment during fabrication.
Corrosion resistance levels
The various grades of stainless steel have varying levels of corrosion resistance. Austenitic stainless steels have the highest levels of corrosion resistance as they contain high levels of chromium in their composition. They are suitable when corrosion resistance is paramount in the intended application. However, they can be costlier than martensitic and ferritic stainless steels that have less nickel or chromium, which translates in reduced corrosion resistance. They are suitable for applications that involve the indoor use of stainless steel as this limits exposure to weather and other corrosive elements.
Strength and ductility requirements
Stainless steel grades vary in strength and ductility with austenitic and duplex stainless steel offering greater toughness and ductility compared to ferritic and martensitic steels. Stainless steel grades with high levels of nickel have greater strengths and are suitable for applications in the pipeline, construction, and manufacturing industries where high strength is paramount in the resultant structures.
Stainless steel has numerous grades, all of which have different properties and are suitable for varying applications. Understanding these factors as pertains to your intended application can guide you to choose the ideal grade for the best stainless steel structures and equipment.