S32750 / 2507 Super Duplex Stainless Steel Good Resistance To General Corrosion

Super duplex stainless S32750 ( 2507) for oil and gas such as valves, fittings, shafts and pump parts etc

1 PRODUCT

Super duplex stainless steel S32750 ( 2507) for oil and gas production equipment such as valves, fittings, shafts and pump parts etc.

S32750 is available from us as round bar, flat bar, hexagonal bar, shaped bar, forging, forging block, plate, sheet, strip, wire, pipe and tubes, fasteners, bolts & nuts etc.

2 EQUIVALENT DESIGNATION

W.Nr. 1.4410, NAS 74N, F53, 00Cr25Ni7Mo4N

3 OVERVIEW

S32750 stainless is the most common super duplex stainless steel with a microstructure consisting of austenite and ferrite phases in approximately equal amounts. The chemical composition and microstructure of S32750 impart a good combination of strength, corrosion resistance and toughness.

The yield strength of annealed S32750 is twice that of typical austenitic stainless steels possessing comparable impact strength. This strength increase is accompanied by slightly reduced ductility or formability. S32750 exhibits good resistance to general corrosion in many acid environments with exceptional resistance to chloride stress corrosion cracking, pitting and crevice corrosion.

S32750 is subject to 885 embrittlement when exposed for extended periods of time at temperatures of approximately 600 to 1000°F (315 to 538°C).

The alloy is also subject to precipitation of sigma phase when exposed to temperatures of approximately 1250 to 1550°F (677 to 843°C) for an extended time. Sigma phase increases strength and hardness but decreases ductility and corrosion resistance.

4 APPLICATION

S32750 may be considered for use in oil and gas production equipment, such as valves, fittings, shafts and pump parts as well as equipment with exposure to a seawater environment.

5 CHEMICAL COMPOSITION

6 PHYSICAL PROPERTIES

Density: 7.82 g/cm³ (0.2817lb/in³)

Melting range: 1050°C (1858°F)

Poisson's Ratio: 0.300

Modulus of elasticity in tension: 29.0 x 10³ ksi

Electrical resistivity: 481.0 ohm-cir-mil/ft

Specific Heat at 68-212˚F (20-100˚C) 0.11 BTU/lb˚F

Magnetic permeability: Ferromagnetic

7 MECHANICAL PROPERTIES

Typical room & elevated temperature tensile properties

1.375"(34.90mm) round bar, Longitudinal specimens, annealed condition(2050°F-1 Hour-WQ)

8 CORROSION RESISTANCE

Due to S32750’s high chromium content (25%) the alloy has good resistance to oxidizing acid concentrations. Reducing acid concentrations that can be tolerated are not as high due to moderate and low levels of molybdenum (4%) and nickel (7%).

S32750 offers excellent resistance to uniform corrosion in various organic acids such as formic and acetic acids and inorganic acids containing chlorides. This alloy provides resistance in strong oxidizing media such as nitric acid and can be considered for use in dilute hydrochloric acid.

Austenitic stainless steels such as Type 304 and 316 can suffer stress corrosion in high-chloride, high-temperature conditions. S32750 provides improved resistance under these conditions and good intergranular corrosion resistance.

Typical corrosion properties

1.375"(34.90mm) round bar, annealed condition

Typical intergranular corrosion properties

1.375"(34.90mm) round bar, annealed condition

Typical pitting and critical crevice temperature

S32750 provides excellent resistance to chloride-induced localized corrosion. An indicator of excellent chloride pitting and crevice corrosion is its high Pitting Resistance Equivalent Number (PREN) determined by the following chemical equation: (Cr%) + 3.3(Mo%) + 16(N%). S32750 has a PREN greater than 40 compared to a PREN of 25 for Type 316.

1.375"(34.90mm) round bar, annealed condition

9 WORKING INSTRUCTION

Hot working

Heat uniformly to 2200-2300°F (1204-1260°C). Reheat as often as necessary, keeping the temperature above 1850°F (1010°C). Cool forgings in air.

Cold working

Cold working increases strength and hardness. The work hardening rate of S32750 is lower than Type 304, an austenitic stainless steel; however, the annealed strength of S32750 is significantly higher.

Machinability

The machinability of S32750 generally has been between that of conventional Type 316 stainless and Carpenter 22Cr-13Ni-5Mn stainless.

10 HEAT TREATMENT

Annealing

Heat to 1925-2050°F (1051-1121°C) and rapidly quench in water or air.

While the duplex alloys have rather high room temperature strength, they have surprisingly low strength at annealing temperatures. Relative to the common austenitic alloys the duplex alloys generally distort slightly more during annealing.

Hardening

Cannot be hardened by heat treatment. Can be hardened only by cold working. Typical hardness as-annealed is HRC 25.

Stress relieving or deliberate slow cooling is not recommended due to possible embrittlement, which can result from exposure in the range of 650-1830˚F. ASTM test method A923/A (metallographic technique) or A923/C (corrosion test technique) are often employed to verify appropriate heat treatment.

11 COMPETITIVE ADVANTAGE

(1) More than 50 years experience of research and develop in high temperature alloy, corrosion resistance alloy, precision alloy, refractory alloy, rare metal and precious metal material and products.
(2) 6 state key laboratories and calibration center.
(3) Patented technologies.
(4) Excellent performance

12 STANDARD SPECIFICATION

ASME section VIII, division I, code case 2047

NACE MR0175

Chemical composition: GB/T 20878

Welded tube and pipe: ASTM A789 / ASME SA789, ASTM A790 / ASME SA790

Bar and rod: ASTM A479, ASTM A276,

Plate, sheet and strip: ASTM A240 / ASME SA240

Fastener: GB/T5782 2507

13 BUSINESS TERM