The Difference between Stainless Iron and Stainless Steel—Part One

How to identify stainless steel and "stainless iron" articles? It can be identified from the marks that many stainless steel products such as stainless steel pipes are stamped with steel seals, such as 13-0, 18-8, etc. The number in front of the short line indicates the chromium content of the product, and the number behind the short line indicates the nickel content of the product. Like 13-0, it only contains chromium and no nickel, commonly known as "stainless iron"; and 18-8 means that the product contains chromium and nickel, which is exactly the stainless steel.

Identify by sound:
Knocking on stainless steel or "stainless iron" products can also be used as a method. Using permanent magnets to attract: real stainless steel is not attracted by magnets, while "stainless iron" can be attracted by magnets. Although there are differences in properties between stainless steel and stainless iron, their corrosion resistance is obviously superior to forged iron and cast iron cookware.

Austenitic stainless steel:
Austenitic stainless steel is stainless steel with austenitic structure at normal temperature. When the steel contains about 18% Cr, 8%-10% Ni and 0.1% C, it has stable austenite structure. Austenitic Cr-Ni stainless steel includes famous 18Cr-8Ni steel and high Cr-Ni series steel developed by adding elements such as Mo, Cu, Si, Nb and Ti.

Austenitic stainless steel is non-magnetic and has high toughness and plasticity, but its strength is low, so it can not be strengthened by phase transformation, but can only be strengthened by cold working. If S, Ca, Se, Te and other elements are added, it has good free cutting property. This kind of steel can resist the corrosion of sulfuric acid, phosphoric acid, formic acid, acetic acid and urea if it contains Mo, Cu and other elements. If the carbon content in this kind of steel is less than 0.03% or contains Ti and Ni, its intergranular corrosion resistance can be significantly improved.

Austenitic stainless steel with high silicon content has good corrosion resistance with concentrated nitric acid. Austenitic stainless steel has been widely used in all walks of life for its comprehensive and good properties.