Stainless steel tubes are hollow, long, circular steel bars, primarily widely used in industrial pipelines for oil, chemical, light industry, and mechanical instruments, as well as in mechanical structural components. Additionally, with equal bending and torsional strength, they are lighter in weight, thus extensively used in the manufacturing of mechanical parts and engineering structures.
Stainless steel tubes can be categorized by composition into Cr series (400 series), Cr-Ni series (300 series), Cr-Mn-Ni series (200 series), and precipitation-hardening series (600 series). 200 Series — Chromium-Nickel-Manganese Austenitic Stainless Steel. 300 Series — Chromium-Nickel Austenitic Stainless Steel.
301 - Excellent formability for molding products. Also rapidly hardens through mechanical processing. Good weldability. Higher wear resistance and fatigue strength than 304 stainless steel.
302-----Corrosion resistance similar to 304; due to higher carbon content, it has better strength.
303 - Added small amounts of sulfur and phosphorus for easier machining than 304.
304——Also known as 18/8 stainless steel. The GB grade number is 0Cr18Ni9. 309——Has better temperature resistance than 304.
316 - A widely used steel grade after 304, primarily used in industrial and equipment applications. The addition of molybdenum gives it a unique corrosion-resistant structure. Due to its superior chloride corrosion resistance compared to 304 stainless steel tubes, it is also used as "shipboard steel." SS316 is typically used in nuclear fuel recovery systems. 18/10 grade stainless steel tubes usually meet this application level as well.
Model 321 — Similar to 304 in all other performance aspects, except for the addition of titanium, which reduces the risk of weld seam rust.
400 Series - Ferritic and Martensitic Stainless Steel
408 - Good heat resistance, mild corrosion resistance, 11% Cr, 8% Ni.
409—Economical grade (US/UK), commonly used for automotive exhaust systems, belongs to ferritic stainless steel (chrome steel).
410—Martensitic (high-strength chromium steel), good wear resistance, poor corrosion resistance.
416—Added sulfur to improve the material's processing properties.
420 "Tool Steel" Martensite, similar to early stainless steel like high-chromium Böhler steel. Also used for cutlery, it can be polished to a very high shine.
430—Ferritic stainless steel, decorative, e.g., for automotive accessories. Good formability, but lower temperature resistance and corrosion resistance.
440—High carbon, high strength tool steel, with higher carbon content. After proper heat treatment, it can achieve higher yield strength, with hardness up to 58HRC, and falls into the category of hard stainless steel. Common applications include razor blades. There are three common types: 440A, 440B, and 440C, as well as 440F (easier to machine).
500 Series — Heat Resistant Chromium Alloy Steel.
600 Series - Martensitic precipitation-hardening stainless steel tube.
