UNS Alloy Designation S32750
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G ENERAL
S32750 is the most common super duplex alloy.Tubular production at Rath utilizes autogenous fusion welding of continuous strip. The weld is fully cold-worked for subquent bright solution annealing.
The 2507 generic-name results from a nominal 25% Chromium and 7% Nickel composition.Plea e the chemical composition table for more information.
Most duplex alloys are lected for rvice becau of their excellent stress corrosion cracking (SCC) resistance and room temperature yield strength relative to austenitic stainless steels, specifically austenitic stainless alloys 304,316, and 317.
It is the duplex austenite-ferrite structure, which enhances room temperature strength and SCC resistance relative to the common austenitic alloys 304, 316, and 317.
The ferrite pha imparts SCC resistance, while the austenite pha retains much of the excellent
ductility and formability of the fully austenitic stainless alloys. This micro-structural pha balance has been optimized by Rath’s strip
sleeperssuppliers and is normally maintained within a
30-50% ferrite range.
The room temperature yield strength of 2507 is typically double that of conventional austenitic stainless steels. This strength increa is accompanied by slightly reduced ductility or formability. When this significant strength increa is considered, designed ction thickness and resulting ction weight can often be reduced.This can often partially offt any cost increa for the alloy.
即刻出发英文版R AT H M A N U FA C T U R I N G C O., I N C .
2505 FOSTER AVENUE, JANESVILLE, WISCONSIN 53545 U.S.A.PHONE (608) 754-2222 FAX (608)
S TAINLESS , D UPLEX & N ICKEL
ALLOY ,
T UBING & P IPE
T ECHNICAL D ATA S HEET A LLOY 2507S UPER D UPLEX S TAINLESS ALLOY
S PECIFICATION C OVERAGE
Form ASTM ASME Welded Tubing A789SA789Welded Pipe A790SA790
Forms Below are available from other Producers
Bar
A479Sheet, Strip, Plate A240
ASME Section VIII, Division 1 Code Ca 2047
NACE MR-0175
Microstructure of 2205 tube. The ferrite pha is slightly darker due to the NaOH etch ud. Weld is on the lower right of photo.
Physical Properties1
Density: 0.285 lb/in3(7.79 g/cm3) Specific Heat at 68-212˚F (20-100˚C)
0.11 BTU/lb˚F
Thermal Conductivity: 8.2 BTU-ft/hr-˚F
Thermal Coefficient of Expansion Modulus of Elasticity in Tension
29 x 106psi
Electrical Resistivity: 33.5 x 10-6Ω-inch Magnetic Permeability
Ferromagnetic Mechanical Properties
Room Temperature Tensile and Harness Annealed 2507 requirements and typical tensile results are listed below:
I MPACT T ESTING
Becau of its significant ferrite content 2507 will likely undergo a transition from ductile fracture to brittle at lower temperatures (DBTT). For ba metal this transition generally occurs below -50˚C. Improper welding or heat treatment procedures can adverly affect impact values and also affect corrosion resistance.
To verify appropriate processing a Charpy V-Notch (CVN) minimum absorbed energy is sometimes specified (ASTM test method A923/B, plate and bar and heavy wall tubulars). However, impact testing of thin wall tubing and pipe is impractical due to specimen size limitations. If this is the ca ASTM test method A923/A or A923/C should be substituted. A923/C does not currently list a test temperature for 2507; Rath would suggest a temperature of 50 or 55˚C until a temperature is defined within A923. For comparison the alloy 2205 test temperature is 22˚C for welded products.
H EAT T REATMENT
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2507 should be annealed in the range of 1925-2060 ˚F (1052-1127 ˚C) and cooled as quickly as possible. 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.
说课技巧S32750
Element Limiting Nominal C0.0300.020
Mn 1.20.8
P0.0350.025
S0.0200.001
为您效劳Si0.80.025
Cr24.0-26.025.0
Ni 6.0-8.07.0
viber是什么Mo 3.0-5.0 4.0
N0.24-0.320.28
Fe Balance Balance Cu0.5-Values are Weight Percent
Single values are maximums Yield Strength 80 ksi110 ksi (0.2% Offt)(552 MPa)(759 MPa)
Ultimate 116 ksi136 ksi Strength(800 MPa)(938 MPa)
Elongationget out
15%30% (in 2 inch)损益表格式
Hardness32 Rc Max.26 Rc Tensile
ASTM &
ASME
Minimums
Typical
Tubing
English Metric
68-200˚F7.2 x10-6/˚F20-100˚F13.0 x10-6/˚C 68-400˚F7.5 x10-6/˚F20-200˚F13.5 x10-6/˚C 68-600˚F7.8 x10-6/˚F20-300˚F14.0 x10-6/˚C 68-800˚F8.0 x10-6/˚F20-400˚F14.5 x10-6/˚C C HEMICAL C OMPOSITION
proportionmoderate and low levels of molybdenum (≈4%) and nickel (≈7%).
SCC susceptibility of stainless steels as a function of temperature and chloride concentration. The 2507 data points did not crack2.
Pitting
Pitting and crevice corrosion resistance is generally a function of an alloy’s chromium, molybdenum and nitrogen contents. Calculated indexes have been devid to roughly predict and rank alloys for pitting resistance bad on the elements (in weight-%). The higher the index the higher the predic
ted pitting corrosion resistance. The most common index ud for duplex alloys is: Pitting Resistance Equivalence Number (PRE or PREN) = %Cr + (3.3 x %Mo) + (16 x %N)
Alloy PREN%Cr%Mo%N
25-646.520.5 6.90.2
250742.2254.25
2205352230.2
9043520 4.5–
3162417 2.10.06
ASTM G48A Ferric chloride pitting test results for R a t h’s tubular products are displayed below and are compared to alloy 2205. The results are for 72-hour tests, with specimens prepared as recommended in G48A. Various producers will adverti resistance at significantly higher temperatures. It has been Rath’s experience that such numbers are typically derived using abbreviated tests and occasionally pre-pickled specimens.
W ELDING
Matching filler metals are available. A maximum interpass temperature no higher than 300˚F (150˚C ) should be ud. Low heat input is suggested, under 38kJ/in (1.5kJ/mm) particularly if no post weld heat treatments are planned. Dissimilar autogenious welds to fully ferritic materials should be avoided as the weld may become nearly fully ferritic. Filler metals can be lected bad on the dissimilar alloy being joined to develop some but not excessive weld ferrite. R EFERENCES
1Avesta Sheffield Inc. SAF 2507, p2
2Sandvik SAF 2507: A High Performance Duplex Stainless Steel, Sandvik Steel, Sweden, March 1990
