• A manufacturer for special materials pipes, tubes,fittings,materials including nickel-based alloy, austenitic, ferritic, duplex stainless steel
  • stainless steel seamless pipe,duplex stainless steel seamless tubes, nickel alloy, nickel base alloy seamless tube and pipe,butt-welding fitting, elbow, tee, cross, flange,valve.
  • Zhongzhou Special Alloy Tube Co.,ltd is glable special alloy and stainless steel products company, which is international piping system material manufacturer and upplier, office located in Shanghai. In glable business, we have sucess to entrying North America, Europea, East Asia, Austrialia,Africa market.Our focus on natural gas transportation,offshore unit,chemical refining,nuclear power,shipbuilding,steel structure,machining and so on piping system engineering. We have strong resources integration, production and processing base are located in Shanghai and Jiangshu province, The factories in Shanghai and Jiangsu,which have vacuum smelting, non-vacuum smelting, horizontal continuous casting, forging, heat treatment and production lines advanced in the industry, and has international advanced technology and complete inspection means. Produces focus on : nickel base alloy,cobalt base alloy,iron base alloy,austenitic stainless steel,super austenitic stainless steel,duplex and super duplex stainless steel,high alloy material products; type are bars,pipes,tubes,fittings,flanges,which are widely used in metallurgy,cars,thermal power, nuclear power, petro-chemical, aviation and aerospace, rail transportation , paper industry,water industry and so on. Material and size as follows: Nickel based Alloy : ASTM SB163, SB165, SB444, SB622, SB407, SB535, SB677, SB668, SB729,Inconel 600,601,625,670,690,718,X-750;Inconel 800,800H/HT,825,840,901,926,330,20;Hastelloy C-276 Super stainless steel: 904L,254MO Duplex/Super Duplex UNS S31803,S32205,S32750,S32760, ASTM A/SA312, A/SA213, A/SA269, EN10216-5 Austenitic Pipe & Tube Standard:GOST9941-81, GOST5632-72 .ASTM/ASME A312/SA312, A269/SA269, ASTM A511, EN10216-5,DIN17458-85,DIN17456-85,JIS G3459,JISG3463,JISG3448,JISG3446,304,304L,316,316L,316Ti,310S,309S,321,321Ti,347 Oil and Gas Cement and Minerals Fertilizers and Petrochemicals Metallurgy and cars industry Mechanical industry Wastewater Treatment and other water industry paper industry, aviation and aerospace Transmission and rail transportation thermal power and other power Generation nuclear power Environmental and Safety our strong supporting layer and our sales’ professional skills will help customers to supply efficient and timely packaged supporting serivces. We have some stock bars ,pipes, fittings .Our quality is always satisfied by our clients, we are strictly controling the whole production and testing. We will always adhere to the policy of
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    Duplex steel and PRE value

    Duplex steel and PRE value


    To evaluate the ability of duplex stainless steel to resist pore  (point) corrosion in a chloride environment, the equivalent pitting  resistance (PRE) PRE =% Cr + 3.3% Mo + 16% N

    Super Duplex Stainless Steel: Duplex steel with PREN> 40, containing 25%  Cr and high molybdenum (> 3.5%) and high nitrogen (0.22% ~ 0.30%).  The main grades are UNS S32550 (UR52N +), S32750 2507) and S32760 (Zeron 100).

    Super  duplex stainless steel: refers to the further increase of chromium, molybdenum, nitrogen content in steel to obtain higher strength and more  excellent corrosion resistance, PRE value of nearly 50 super duplex  stainless steel. Such as SAF2707 HD and SAF 3207 HD.

    In the development of duplex and super duplex stainless steel, some  problems such as physical metallurgy encountered have drawn people's  attention.

    1,  the amount of Cr% + Mo% steel should be greater than or equal to 21%,  in order to prevent cold forming caused martensitic transformation  leading to the decline of steel (corrosion) performance. Domestic research to improve the 18-5 duplex stainless steel (Cr + Mo  content of 21%, N content of 0.07% and 0.10%) cold deformation on the  amount of martensite and steel corrosion resistance showed that.


    The formation and increase of the amount of martensite will reduce the  stress corrosion resistance and pitting corrosion resistance of this  steel.
     
    2.  In order to increase the corrosion resistance of duplex stainless  steel, the thermal stability of duplex stainless steel caused by Cr% +  Mo% greater than or equal to 35% should be decreased when the content of  chromium and molybdenum should be increased. The intermetallic phase  precipitates Resulting in plasticity, toughness, thermal processing and welding  process, and corrosion resistance deterioration to take the necessary  precautions.

    Nitrogen is a very useful and important element, but adding a large amount of nitrogen will cause chromium nitride
    And  the precipitation along the grain boundary, resulting in intergranular  corrosion and other corrosion damage and toughness decline in the amount  of nitrogen in steel exceeds the amount of solid solution in the steel  solidification process due to the release of nitrogen will cause a lot  of waste; if in order to improve Nitrogen  in steel solid solubility, adding a large amount of manganese, the  resulting damage caused by the formation of manganese sulfide should  also be assessed.


    Post time: Dec-07-2017