Duplex Steel Flange Per S31803 /A182 F51

China Duplex Steel Flange Per S31803/A182 F51, Find details about China F51 Flange, S31803 Flange from Duplex Steel Flange Per S31803/A182 F51

Basic Info.

Model NO.

Flange

HS Code

73072100

Model NO.

Flange

HS Code

73072100

Product Desciption

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.

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	-	-