304 stainless Steel Pipe classification There are many kinds, the first is seamless pipe and straight seam welded pipe, followed by the most basic classification is the structure of 304 stainless steel pipe and industrial fluid transport with 304 stainless steel pipe.
Hot rolled (extruded seamless steel tubes):
Round tube billet → heating → perforation → three-roll inclined rolling, continuous rolling or extrusion → de-tube → sizing (or reducing) → cooling → billet Tube → straightening → hydraulic test (or flaw detection) → mark → warehousing. Cold drawn (rolled) seamless steel tubes: round tube billet → heating → perforation → head → annealing → pickling → oiled (copper plating) → multi-Channel cold drawing (cold rolling) → billet Tube → heat treatment → straightening → hydraulic test (flaw detection) → mark → warehousing.
【Heat treatment Process】
304 stainless steel pipe solution treatment temperature of 1080-1100 ℃, cooling mode is water-cooled or air-cooled. Cold processing intermediate annealing temperature of more than 850-970 ℃, insulation for a certain time after water cooling. After solution treatment, the microstructure of Steel was austenite, and sometimes there were few ferrite.
304 stainless steel tubes suppress carbide precipitation during welding and can be welded using a common method. Manual arc welding, carbon 0.04%-0.06% thin section size of 304 stainless steel can be used 002 welding rod, welding can not produce intergranular corrosion tendency, for thick section ruler, to maintain the intergranular corrosion resistance after welding, need to be welded after heat treatment, if not heat treatment, Should be changed to 304L stainless steel or stable austenitic stainless steel.