Astma789 790 Duplex Steel Seamless And Welded Tube - China

ASTMA789 790 Duplex steel seamless and welded tube

Introduction:

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.

Benefits:

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.

Uses:

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:

• Posted By: Ningbo Junfun International Trade Co.,Ltd

• Phone: 8605748200788

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

• Email:

• 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'
  
  requirements.
  
  
  
  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.