Basic Info.
Standard
ANSI, DIN, GOST, En1092-1
Manufacturing Way
Forging
Individual Drawing
Welcome
Transport Package
Pallet/Wooden Case
Product Description
Duplex stainless steel are extremely corrosion resistant, work hardenable alloys. Their microstructures consist of a mixture of austenite and ferrite phases. As a result, duplex stainless steels display properties characteristic of both austenitic and ferritic stainless steels.
This combination of properties can mean some compromise when compared with pure austenitic and pure ferritic grades. Duplex stainless steel are in most cases, tougher than ferritic stainless steel. Strengths of duplex stainless steels can in some cases be double that for austenitic stainless steels.
Whilst duplex stainless steel are considered resistant to stress corrosion cracking, they are not as resistant to this form of attack as ferritic stainless steel. However, the corrosion resistance of the least resistant Duplex stainless steel is greater than that for the most commonly used grades of stainless steel, i.e. 304 and 316.
Duplex stainless steel are also magnetic, a property that can be used to easily differentiate them from common austenitic grades of stainless.
Raw Material Specification
Duplex 31803(2205,F51)
What is duplex
Duplex is a stainless steel with a dual phase microstructure, compromising of approximately 50% of austenitic and 50% of ferrite. This gives the material an excellent combination of high strength and corrosion resistance. The resistance to pitting corrosion may be compared to other grades by using the pitting index (PREN). Higher PREN will give better the pitting resistance.
Delivery conditions
Duplex materials shall be solution annealed and liquid quenched. Duplex tubes are also capable of being cold worked to higher yield strength.
Specific alloys
There are several specific alloys within this category. Common alloys for oil and gas well applications are:
UNS S31803
This is a duplex in the ISO category 22-5-3. Typical yield strength in the solution annealed and water quenched condition is 450MPa and the tensile strength is 620MPa. Trade names are Sandvik SAF 2205, Zeron 25 and Sumitomo SM22CR. PREN for ISO category 22-5-3 shall be minimum 35 to be in accordance with ISO 13680.
UNS S31260
This is a duplex in the ISO category 25-7-3. This duplex is delivered with increased amount of Cr and Ni, but also some cupper (0.2 - 0.8%Cu) and tungsten (0.1 - 0.5%W). A trade name is DP-3 and Sumitomo SM25CR. Typical yield strength for this alloy is 515MPa. PREN for ISO category 25-7-3 shall be minimum 37.5 to be in accordance with ISO 13680.
Applications
Typical applications are pipes, coiled tubing and subsea equipment. Some operators do not recommend duplex stainless steel materials in oil and gas producing wells due to failure experience. The alloys have lower pitting resistance and H2S limit compared to superduplex.
Chemical composition
Table 1: Chemical composition, UNS S31803
| C | Si | Mn | P | S | Ni | Cr | Mo | Al | Ti |
Min | - | - | - | - | - | 4.5 | 21 | 2.5 | - | - |
Max | 0.03 | 1 | 2 | 0.03 | 0.02 | 6.5 | 23 | 3.5 | - | - |
| Nb(Cb) | Cu | Co | B | Fe | W | V | N | O | PREN |
Min | - | - | - | - | Bal | - | - | 0.08 | - | 31 |
Max | - | - | - | - | - | - | - | 0.2 | - | 38 |
Pitting index PREN = %Cr + 3.3 (%Mo +0.5%W) + 16%N |
Mechanical and physical properties An introduction to mechanical and physical properties follows. These properties are dependent on the alloy, heat treatment and cold working. Detailed data is available in material datasheets from suppliers and material property handbooks. Table 2: Mechanical properties, UNS S31803, grade 110ksi, cold worked Mechanical properties | -40ºC | 20ºC | 200ºC |
Tensile strength, yield (min.) | - | 758 MPa (110ksi) | - |
Tensile strength, yield (typical) | - | - | - |
Tensile strength, ultimate (min.) | - | 862 MPa (125ksi) | - |
Tensile strength, ultimate (typical) | - | - | - |
Tensile modulus (typical) | - | 198 MPa | 184 MPa |
Torsion modulus (typical) | - | - | - |
Yield point (Mpa)min | | 450 | |
Elongation (min.) | - | 12% | - |
Red. of area (min.) | - | - | - |
Charpy V-notch impact (typical) | - | - | - |
Fracture toughness KIC (typical) | - | - | - |
Hardness (ISO 15156-3 limit) | - | See below | - |
Hardness (typical) | - | See below | - |
Fatigue strength (% of T.S.U.) | - | - | - |
These alloys will have strength reduction with higher temperature. Available grades for tubes in accordance with ISO 13680 are 65, 110, 125 and 140ksi. Grade 65 is solution annealed (SA). The rest of the grades are cold worked (CW). Cold working will make a non-homogeneous material. Maximum hardness for each grade is: Table 3: Delivery conditions and hardness limitations Grade | Delivery condition | HRC (max) available | HRC (max) ISO 15156-3 |
65 | SA | 26 | 36 |
110 | CW | 36 | 36 |
125 | CW | 37 | 36 |
140 | CW | 38 | 36 |
Table 4: Physical properties, UNS S31803, grade 110ksi Physical properties | -40ºC | 20ºC | 200ºC |
Density | - | 7.85 g/cm3 | - |
Thermal expansion coefficient | - | 12.5 10-6K-1 | 12.5 10-6K-1 |
Thermal conductivity | - | 13.7 Wm-1K-1 | 18.1 Wm-1K-1 |
Specific heat | - | 468.2 JKg-1K-1 | 525.5 JKg-1K-1 |
Electrical resistivity | - | - | - |
Poisson's ratio | - | 0.25 | 0.23 |
Magnetic permeability | - | - | - |
Machining and welding properties Cold worked grades can be difficult to machine and is prone to distortion. Have this in mind for critical parts like landing nipples (tolerances). The operator must be trained and must follow guidelines from the suppliers. Duplex has good welding properties. Corrosion and mechanical properties of the welded zone similar to the parent material can be obtained following recommended procedures from the supplier. Failure mechanism resistance Table 5: Failure mechanism resistance Poor | Good | Excellent |
Chloride Stress Corrosion Cracking | Erosion corrosion | CO2 corrosion |
General corrosion at low pH | Pitting and crevice corrosion | - |
Sulphide Stress Cracking | - | - |
Surface treatments
NA
Processing problems
Cold worked grades of duplex will have residual stresses.
Shipped Flange Photos
Production Range
DN15-DN3000
Maximum weight 6tons
25,000tons production annual year
Manufacturing Standard
ANSI B16.5,ANSI B16.47 Series A&B,ANSI B16.48,ANSI B16.36
API 605,API 16D,API 17D
BS4504,BS3293
DIN
AS
EN1092-1
GOST
EEMUA145
Inspection Certificate
EN10204-3.1
EN10204-3.2 byTUV,BV,Lloyds,GL,DNV,SGS,ABS,RINA,Moody or other third parties
Address:
Building 9, No. 1558, Kangqiao Rd., Pudong, Shanghai, China
Business Type:
Manufacturer/Factory, Trading Company
Business Range:
Chemicals, Construction & Decoration, Industrial Equipment & Components, Manufacturing & Processing Machinery, Metallurgy, Mineral & Energy, Tools & Hardware
Management System Certification:
ISO 9001, ISO 14001, ASME
Company Introduction:
Dingxiang CHN Flange Forging Co., Ltd. is located in the State Dingxiang named"hometown of forging", founded in 2006 invested by TianYuan(HK) International Limited be specialized in manufacturing various kinds of high quality flange and other forging.
Being a designer and manufacturer of flange and forgings in the industry. We provide both standard and customized designs in a large range of different pipeline system. Our main products include Welding Neck, Slip-on, SocketWelding, Threaded, Binld according to ANSI, DIN, JIS, EN, made of ASTM A105, A350, A694, A182, ect. Our engineers are able to design the right products to fit your application and the best solution for your requirements. The products have been wildely used in the industries of petroleum, chemical, foodstuff, metallurgy, construction, electric power and so on.
We have a 4, 000tons Hydraulic Machine and 6300 Ring Rolling Machine operating flange&ring production, the maximum outside diameter is up to 6000mm, maximum gross weight up to 6tons. Our annual production capacity of Flange is 25000tons;
We do a whole set of chemical and mechanical performance test, metallurgical structure, hardness test, NDE test, salt-fog test, film thickness test, roughness test, and the lowest temperature of impact test can be -196 degree C.
We treat Quality, Customer, Market, Upgrade as the most important.