Stainless steel tubes are hollow, elongated circular steel bars, primarily widely used in industrial pipelines for oil, chemical, light industry, and mechanical instruments, as well as for mechanical structural components. Moreover, due to their lighter weight with the same bending and torsional strength, they are also extensively utilized 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 welding properties. Higher wear resistance and fatigue strength than 304 stainless steel.
302-----Corrosion resistance similar to 304; higher carbon content results in better strength.
303——Add a small amount of sulfur and phosphorus to make it easier to machine than 304.
304 - Also known as 18/8 stainless steel. GB brand number is 0Cr18Ni9. 309 - Has better temperature resistance than 304.
316 - A widely used steel grade following 304, primarily used in industrial and equipment applications. The addition of molybdenum gives it a special corrosion-resistant structure. Due to its superior chloride corrosion resistance compared to 304 stainless steel pipes, it is also used as "shipboard steel." SS316 is typically used in nuclear fuel recovery units. 18/10 grade stainless steel pipes usually meet this application level as well.
Model 321—Similar to 304 in performance, except that the addition of titanium elements reduces the risk of material weld seam corrosion.
400 Series – Ferritic and Martensitic Stainless Steel.
Good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.
409—Inexpensive model (UK/US), commonly used for car 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" Martensitic steel, similar to early stainless steels like Beryllium Chrome steel. Also used for cutting tools, which can be highly polished.
430—Ferritic stainless steel, decorative, e.g., for automotive accessories. Good formability, but poor temperature resistance and corrosion resistance.
440—High-strength tool steel with a slightly higher carbon content. After proper heat treatment, it can achieve high yield strength, with hardness up to 58HRC, placing it in the category of hard stainless steels. 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 tubes.