Standard Cr-Ni-Mo Stainless Steels
Which Include 1.4401 316 | 1.4404 316L | 1.4571 316T
The grades referred to are molybdenum-containing austenitic stainless steels which aim to provide improved corrosion resistance compared to the standard Cr-Ni steel grades used in corrosive process environments.
The addition of molybdenum provides improved resistance to pitting and crevice corrosion in environments containing chlorides or other halides.
The grades quoted here are used in applications handling a wide range of chemicals used by process industries. These include food and beversges, medical,pharmaceutical, as well as other potentially corrosive environments or fluids use.
Modern stainless steels are today easily produced with a low carbon content, therefore the risk of chromium carbide precipitation has significantly decreased.
Intergranular corrosion caused by chromium carbides is therfore rarely an issue nowdays, but stabilised grades, often type 1.4571, are still specified. Non-titanium-stabilised grades generally have a better surface finish than titanium-stabilised grades.Given their fully austenitic structure, all these grades are
non-magnetic in the annealed condition but may become slightly magnetic as a result of phase transformation due to cold working or welding. The high nitrogen grades, i.e. 1.4406 and 1.4429 apart from an increased mechanical strength also have a more stable austenitic structure leading to a lower permeability in comparison to the other standard Cr-Ni-Mo stainless steel grades.