THINGS TO CONSIDER WHEN CHOOSING A STAINLESS-STEEL GRADE Stainless steel is a commonly used material in applications ranging from medical instruments or chemical storage to transport or power generation because of its high corrosion resistance, hygiene, and strength. Stainless steel is available in a diverse range of grades that let it accommodate different applications across a lot of industries. But, because there are many grades available, you need to have some knowledge of how to choose the appropriate one. •
Formability of the Stainless Steel
If you want to use stainless steel for applications that require good formability, steer clear of the martensitic group of stainless steels. Instead, choose an austenitic grade like 304 or a ferritic grade like a 430. Often, stainless steel is the right choice in terms of formable stainless steels. •
Prioritize Strength, Ductility, and Toughness
Stainless steel contains 10–30% chromium as its alloying element, which is what helps it resist corrosion. The nickel addition in austenitic grades provides the highest toughness and ductility among stainless grades. Grades high in chromium, and nickel are the most resistant to corrosion. While the hardness of carbon steels can be increased by heat treatment, austenitic stainless is hardened by cold working operations like rolling, bending, swaging, or drawing at temperatures below the recrystallization temperature. •
Weldability
Welding stainless steel can result in issues like hot cracking, intergranular corrosion, and stress corrosion cracking. Typically, the stainless steels are the most weldable type. Make sure you to use grades like 304L or 347 when welding this type of stainless steels. This is because 304L tends to have lower carbon while 347 has niobium stabilizers added to it to help in deterring intergranular corrosion. •
Machinability
Although the majority of stainless-steel grades can be machined, the metal is quite susceptible to work hardening. It is important to optimize the machining process to work at a rate which helps alleviate this problem. Also, use machining tools that are kept in good working condition. To increase the machinability of steel, sulfur can be added such as in the case of grade 303. •
Ability to be Heat-Treated
Heat treating the stainless steel, you should be aware of how this process can impact the different stainless-steel grades. Usually, stainless steel and ferritic steels are non-hardenable when treated with heat. Typically, the heat treatable stainless steels are martensitic or precipitation hardened.