Stainless Steel Pipe Material Classification

00 Series - Ferritic and martensitic stainless steel.
408 - Good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.
409 - Cheapest model (Anglo-American), commonly used as an automobile exhaust pipe, ferritic stainless steel (chromium steel).
410 - Martensite (high strength chromium steel), good wear resistance, poor corrosion resistance.
416 - The addition of sulfur improves the processing properties of the material.
420 - "cutting tool grade" martensitic steel, similar to Brinell high chromium steel this earliest stainless steel. Also used in surgical knives, can be made very bright.
430 - Ferritic stainless steel, for decorative purposes, e.g. for car accessories. Good formability, but poor temperature resistance and corrosion resistance.
440 - high strength cutting tool steel, slightly higher carbon content, after appropriate heat treatment can obtain high yield strength, hardness can reach 58HRC, is one of the hardest stainless steel. The most common example is the "razor blade". There are three common models: 440A, 440B, 440C, and 440F (easy to process).
500 Series - Heat-resistant chrome alloy steel.
600 Series - Martensitic precipitation-hardened stainless steel pipe.