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  • Astma789 790 Duplex Steel Seamless And Welded Tube - China

    price: contact company for price

    ASTMA789 790 Duplex steel seamless and welded tube


    Called Duplex Pipe because of its mixed microstructure with

    about equal proportions of ferrite and austenite, duplex

    stainless steels are a family of grades, which range in

    corrosion performance depending on their alloy content. The

    chemical composition based on high contents of Cr and Mo,

    improves intergranular and pitting corrosion resistance,

    respectively. Additions of nitrogen can promote structural

    hardening by interstitial solid solution mechanism, which

    raises the yield strength and ultimate strength values

    without impairing toughness. Moreover, the two- phase

    microstructure guarantees higher resistance to pitting and

    stress corrosion cracking in comparison with conventional

    stainless steels.

    Duplex is a stainless steel made from a mixture of austenite

    and ferrite phases. Like most austenitic stainless steels,

    duplex has a strong resistance to corrosion, similar to

    those of a Type 304 and 316.

    Unlike similar steels, duplex also displays an improved

    resistance to localized corrosion, particularly pitting,

    crevice corrosion and stress corrosion cracking. And because

    duplex has a lower nickel and molybdenum content than other

    austenitic stainless steels, it can prove a more cost

    effective option due to a lower alloying content.

    Due to its Ferritic qualities, duplex steel also shows very

    good resistance to stress corrosion cracking when compared

    to standard austenitic. In some cases, the strength of

    duplex steel can be up to double that of the most commonly

    used grades of stainless steel.

    Duplex becomes brittle at extreme temperatures so its use is

    normally restricted to a maximum temperature of 300 degrees.

    Duplex also shows signs of embrittlement at - 50 degrees.


    Stronger than 300 series stainless steel which also brings

    weight advantages.

    Cheaper than some stainless steels.

    High resistance to pitting, crevice corrosion and stress

    corrosion cracking.

    Higher heat conductivity and lower thermal expansion than

    austenitic steels.


    Pipes for production and transportation of oil and gas

    Structural and mechanical components

    Heat exchangers

    Cooling pipes

    Cargo vessels and containers

    High strength wiring

    Standard of ASTMA789

    1. Scope*

    1.1 This specification2 covers grades of nominal wall

    thickness, stainless steel tubing for services requiring

    general corrosion resistance, with particular emphasis on

    resistance to stress corrosion cracking. These steels are

    susceptible to embrittlement if used for prolonged periods

    at elevated temperatures.

    1.2 The values stated in either inch- pound units or SI units

    are to be regarded separately as standard. Within the text,

    the SI units are shown in brackets. The values stated in

    each system are not exact equivalents; therefore, each

    system must be used independently of the other. Combining

    values from the two systems may result in nonconformance

    with the specification. The inch- pound units shall apply

    unless the M designation of this specification is specified

    in the order.

    2. Referenced Documents

    2.1 ASTM Standards: 3

    A 480/ A 480M Specification for General Requirements for

    Flat- Rolled Stainless and Heat- Resisting Steel Plate, Sheet,

    and Strip

    A 1016/ A 1016M Specification for General Requirements for

    Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless

    Steel Tubes

    E 527 Practice for Numbering Metals and Alloys ( UNS)

    2.2 SAE Standard: 4

    SAE J 1086 Practice for Numbering Metals and Alloys( UNS)

    Company Contact:

    • Phone: 8605748200788

    • Address: B-2320, ShiJi Plaza,Daliang Street No.118,Haishu D, Ningbo, China

    • Email: Email

    Published date: September 14, 2015 -

    • Business Description: Junfun is an available Chinese supplier located in Ningbo city. We focus

      on steelfiled, under the brand name of "Junfun", including seamless

      steel pipe,welded steel pipe, ball valve, butterfly valve, flange,

      elbow, tee,etc., which are used in industries like petrol,

      chemical,pharmaceuticals, environmental protection, food&water,

      conservancy,shipbuilding, automobile, aerospace, pressure vessels,

      mechanical processing, etc. Professional and experienced workers, strict

      supply chain management ensures the fulfillment of clients'


      From the raw material to finished products, we insist on recording each

      step of production situation and test, which can track the quality

      problem. Welcome inquiry, welcome cooperation.

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