What are the materials of stainless steel round pipes?

Stainless steel round pipe is a welded pipe made of alloy material and is widely used; however, various industries have different material properties, processing performance, and price budgets, so a variety of material classifications are derived. What materials are stainless steel round pipes made of? They are mainly divided into austenite, ferrite, and martensite. Let’s take a look at their characteristics.

Stainless steel round pipes can be divided into decorative stainless steel round pipes, industrial stainless steel round pipes, and sanitary stainless steel round pipes according to their uses.
Stainless steel round pipes can be divided into seamless pipes and welded pipes according to the production technology process. Seamless steel pipes can be divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes and extruded pipes. Cold-drawing and cold-rolling are secondary processing of steel pipes; welded pipes are divided into straight seam welded pipes and spiral welded pipes.
Stainless steel material round pipes can be divided into: 201 stainless steel or round pipes, 304 stainless steel round pipes, 316L stainless steel round pipes, etc. according to different materials.
How are stainless steel round pipes processed?
Stainless steel welded pipe production process: raw materials--slitting--welding pipe making--heat treatment--rectification--straightening--end trimming--pickling--hydraulic test--inspection (printing)-packaging--output goods
Cold drawn (rolled) seamless steel pipe: round tube blank → heating → perforation → heading → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → billet tube → heat treatment → straightening → Hydrostatic test (flaw detection)→marking→warehousing.
Hot rolling (extruded seamless steel pipe): round tube blank → heating → perforation → three-roll cross rolling, continuous rolling or extrusion → detubing → sizing (or diameter reduction) → cooling → billet tube → straightening → hydraulic pressure Test (or flaw detection)→mark→warehouse.
1. Austenitic stainless steel
At normal temperature, the stainless steel round tube contains about 18% Cr, 8%~10% Ni, and about 0.1% C, and has a stable austenite structure. Including the famous 18Cr-8Ni steel and the high Cr-Ni series steel developed by increasing the Cr and Ni content and adding Mo, Cu, Si, Nb, Ti and other elements. It is non-magnetic, has high toughness and plasticity, but its strength is low. It cannot be strengthened through phase change and can only be strengthened through cold working.
If elements such as S, Ca, Se, and Te are added, it will have good machinability. In addition to being resistant to corrosion by oxidizing acid media, this type of steel can also be resistant to sulfuric acid, phosphoric acid, formic acid, acetic acid, and urea if it contains elements such as Mo and Cu. etc. corrosion.
If the carbon content of this stainless steel welded pipe is less than 0.03% or contains Ti or Ni, its resistance to intergranular corrosion can be significantly improved. High-silicon austenitic stainless steel has good corrosion resistance to nitric acid.
2. Ferritic stainless steel
Stainless steel round pipes with a mainly ferrite structure under use, contain 11%-30% chromium, and have a body-centered cubic crystal structure. Generally does not contain nickel, and sometimes contains a small amount of elements such as Mo, Ti, Nb, etc. This type of steel has the characteristics of large thermal conductivity, small expansion coefficient, good oxidation resistance, and excellent stress corrosion resistance. It is mostly used to manufacture materials that are resistant to the atmosphere and water vapor. , parts corroded by water and oxidizing acids.
However, it has shortcomings such as poor plasticity, significantly reduced plasticity and corrosion resistance after welding, which limits its application. The application of outside-furnace refining technology (AOD or VOD) can greatly reduce interstitial elements such as carbon and nitrogen.
3. Martensitic stainless steel
Stainless steel round pipes whose mechanical properties can be adjusted through heat treatment are, in layman's terms, a type of hardenable metal; typical grades are Cr13, such as 20Cr13, 30Cr13, 40Cr13, etc. The hardness after quenching is high, and different tempering temperatures have different strength and toughness combinations. It is mainly used in instrument accessories.
According to the difference in chemical composition, martensite can be divided into two categories: martensitic chromium steel and martensitic chromium-nickel steel. According to different structures and strengthening mechanisms, it can also be divided into martensitic stainless steel, martensite and semi-austenitic (or semi-martensite) precipitation hardening stainless steel, and maraging stainless steel.
What materials are stainless steel round pipes made of? Austenitic, ferrite, and martensitic stainless steel round pipes are synthesized from elements such as Cr, Ni, C, Mo, Cu, Si, Nb, Ti, Ca, Se, etc. with different contents. Its corrosion resistance, toughness, plasticity, hardness, and strength are all different, and it is used in various industries.