Complaint
The duplex stainless steels have a microstructure, when heat treated properly, of nearly equal proportions of austenite and ferrite. This microstructure ensures that the duplexes are much more resistant to stress corrosion cracking (SCC) than austenitic stainless steels. The specification 0.2% Proof Stress of the duplexes is more than double that of austenitic stainless steels such as the 304 types andu316L types. This often allows down gauging in the design, depending on Young's Modulus and buckling limitations.
The microstructures inside duplex stainless steels are approximately 50 per cent austenite and 50 per cent ferrite, and consequently duplex products share the physical properties of both ferritic and austenitic grades. Duplex stainless steels are resistant to the cracking caused by chloride stress corrosion in austenitic grades, and have improved resistance to localised corrosion. This family of stainless steels has roughly twice the yield strength of their counterpart austenitic grades which means we can use it to design thinner gauge tubing. Higher hardness values provide better wear resistance for high precision tubes.
Duplex steels are easily welded and formed, similar to austenitic grades. Depending on chromium, nickel and molybdenum content, duplex stainless steels are divided into four main categories: lean duplex, duplex, super duplex and hyper duplex. This family of alloys has great advantages in both material and engineered fabrication costs.
Typical applications for this alloy group include heat exchanger tubes, umbilicals, structural tanks, pulp and paper making equipment, pipes and fittings, and seawater handling systems.
Stainless Steel Pipes Material classification |
Stainless steel pipes can be divided into Cr series (400 series), Cr-Ni series (300 series), Cr-Mn-Ni (200 series) and precipitation hardening series (600 series) according to their components. |
200 Series - Chromium-Nickel-Manganese Austenitic Stainless Steels |
300 Series - Chromium-Nickel Austenitic Stainless Steels. |
301-----good ductility, used for molding products. It can also be hardened by mechanical processing. Good weldability. Wear resistance and fatigue strength are better than 304 stainless steel. |
302-----corrosion resistance is the same as 304, because the carbon content is relatively high, so the strength is better. |
303-----it is easier to cut than 304 by adding a small amount of sulfur and phosphorus. |
304-----that is, 18/8 stainless steel. GB grade is 0Cr18Ni9. 309-has better temperature resistance than 304. |
316-----After 304, the second most widely used steel grade, mainly used in the food industry, pharmaceutical industry and surgical equipment, adding molybdenum element to obtain a special anti-corrosion structure. Because of its better resistance to chloride corrosion than 304 stainless steel, it is also used as "marine steel". SS316 is usually used in nuclear fuel recovery units. Grade 18/10 stainless steel pipe generally also meets this application level. |
Model 321-Similar to 304 except that the addition of titanium reduces the risk of corrosion in material welds. |
400 series-ferritic and martensitic stainless steels. |
408-Good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni. |
409 - The cheapest model (British and American), usually used as a car exhaust pipe, is a ferritic stainless steel (chromium steel). |
410-Martensitic (high-strength chromium steel), with good wear resistance and poor corrosion resistance. |
416 - The addition of sulfur improves the processing properties of the material. |
420 - "cutting grade" martensitic steel, the earliest stainless steel similar to Brinell high chromium steel. Also used in surgical knives, can do very bright. |
430-ferritic stainless steel, used for decoration, such as for car accessories. Good formability, but poor temperature and corrosion resistance. |
440-High-strength cutting tool steel, with slightly higher carbon content, high yield strength can be obtained after proper heat treatment, and the hardness can reach 58HRC, which is one of the hardest stainless steels. The most common application example is "razor blades". There are three commonly used models: 440A, 440B, 440C, and 440F (easy processing type). |
500 Series - Heat Resistant Chromium Alloy Steel. |
600 Series-Martensitic precipitation hardened stainless steel pipe. |
| Standard: | ASTM EN DIN GB ISO JIS | Certification: | SGS,ISO,ROHS |
| Length: | 6000-25000mm,etc | Surface: | 2B,2D,BA,NO.1,NO.4,NO.8,8K,Pickling,Bright;mirror,checkered,embossed,hair line, sand blast, Brush, etching, etc |
| Diameter: | 3mm--1000mm, etc | Production Process: | Cold Drawn,Cold Rolled,Bright Anneal etc |
| Thickness: | 0.5-40mm | Surface Treatment: | Standard export package, suit for all kinds of transport, as required. |
| Export Packing: | Waterproof Paper, Steel Strip Packed and other Standard Export Seaworthy Package, or customized package | Loading Port: | Pickled,Passivation,Inside & Outside Mechanical Polishing, BA, Electropolishing (EP) |
| Heat Treatment Condition: | Solution Annealing and water rapid quenched, Bright Annealing,Stess Relieving Heat Treatment for U tubes | Trade Terms: | FOB, CNF,CIF |
| Grade: | 201,202,304,304L,309,309S,310S,316,316L,316Ti,317L,321,347H,409,409L,410,410S,420(420J1,420J2),430,436,439,441,444,446 etc1.4301, 1.4307, 1.4541, 1.4401, 1.4404 ,1.4571, 1.4438, 1.4539, 1.4547, 1.4529, 1.4562, 1.4410, 1.4878, 1.4845, 1.4828, 1.4876, 2.4858, 2.4819 | ||
| Advantage: | 1. high quality surface, clean finished2. corrosion & oxidation resistance, more durable3. high ductility and good toughness4. high strength and to deform5. the use to diversity | ||
| Container Size: | 20ft GP:5898mm(Length)x2352mm(Width)x2393mm(High)40ft GP:12032mm(Length)x2352mm(Width)x2393mm(High)40ft HC:12032mm(Length)x2352mm(Width)x2698mm(High) | ||
