Duplex Stainless Steel

Transcription

1 North American Version Imperial Units Duplex Stainless Steel Steel grades Outokumpu EN ASTM LDX S S3234 LDX S Code.62 S3225/S383. S3275 Characteristic properties Good to very good resistance to uniform corrosion Good to very good resistance to pitting and crevice corrosion High resistance to stress corrosion cracking and corrosion fatigue High mechanical strength Good abrasion and erosion resistance Good fatigue resistance High energy absorption Low thermal expansion Good weldability Applications Heat exchangers Water heaters Pressure vessels Large storage tanks Rotors, impellers and shafts Components for structural design Rebar for concrete construction Firewalls and blast walls on offshore platforms Digesters and other equipment in the pulp and paper industry Cargo tanks and pipe systems in chemical tankers Desalination plants Flue-gas cleaning Seawater systems General properties Ferritic-austenitic stainless steel also referred to as duplex stainless steels, combine many of the beneficial properties of ferritic and austenitic steels. Due to the high content of chromium and nitrogen, and often also molybdenum, these steels offer good resistance to localized and uniform corrosion. The duplex microstructure contributes to the high strength and high resistance to stress corrosion cracking. Duplex steels have good weldability. Chemical composition Table Austenitic Duplex Outokumpu steelname International steel No Chemical composition, % by wt. Typical values UNS ASTM* EN ISO C N Cr Ni Mo Others LDX 2 S E Mn Cu 234*** S I Cu LDX 244 S X Mn Cu 225 Code S3225** I S E S343 34L I S3 L I L N894 94L I Cu S I Cu * common name as listed by ASTM, ** also available as S383, ***also available as EDX 234

2 Outokumpu produces a whole range of duplex grades from the lean alloyed LDX 2 up to the super duplex grade. This publication presents the properties of the most popular grades, namely LDX 2, 234, LDX 244, 225 Code and. Outokumpu offers additional duplex grades for which information can be given upon request or via dedicated datasheets available on our website. Chemical composition The typical chemical compositions of Outokumpu grades are shown in Table. The chemical composition of grade EDX 234 TM is balanced to achieve optimal corrosion resistance and mechanical strength, but it still corresponds to EN.4362/ UNS S3234 standards. The chemical composition of a specific steel grade may vary slightly between different national standards. The required standard will be fully met as specified on the order acknowledgement. Microstructure The chemical composition of duplex steels is balanced to give approximately equal amounts of ferrite and austenite in the solution-annealed condition. Higher annealing temperatures result in higher ferrite contents. Duplex steels are more prone to precipitation of sigma phase, nitrides and carbides than corresponding austenitic steels, causing embrittlement and reduced corrosion resistance. The formation of intermetallic phases such as sigma phase occurs in the temperature range -75 F and decomposition of ferrite occurs in the range F (885 F embrittlement). 2 - Duplex Stainless Steel Exposures at these temperatures should therefore be avoided. In proper welding and heat treatment operations the risk of embrittlement is low. However, certain risks exist, for example at heat treatment of thick sections, especially if the cooling is slow. Figure illustrates the relation between time and temperature that leads to a 5% reduction of the impact toughness. Due to the risk of embrittlement, the duplex steels should not be used at temperatures above F. The maximum temperature and strength value depends on the grade and the design rules being used. Methods for detecting undesirable phases in standard and super duplex stainless steels can be found in ASTM A923 and for lean duplex stainless steel in ASTM A84. Mechanical properties at F Table 2 Minimum values Typical values P H C P (.6 ) H (.6 ) C (.4 ) LDX 2 Yield strength YS ksi Tensile strength TS ksi 94-6 Elongation % Hardness (Brinell) HB max Yield strength YS ksi Tensile strength TS ksi Elongation % Hardness (Brinell) HB max LDX 244 Yield strength YS ksi Tensile strength TS ksi Elongation % Hardness (Brinell) HB max Yield strength YS ksi Tensile strength TS ksi Elongation % Hardness (Brinell) HB max P=Hot Rolled Plate, H=Hot Rolled Coil, C=Cold Rolled Coil and Sheet Code LDX (36 s) (6 min) Time (h) Fig. Curves for 5% reduction of impact toughness to 5% compared to solution annealed condition. Mechanical properties Tables 2 shows the mechanical properties for flat rolled products. Data according to ASTM A24 when applicable. Guidance data on specification and design values for various mechanical and physical properties of the duplex stainless steels are shown in tables 3-6. Actual specification LDX LDX Code Fatigue The high tensile strength of duplex steels also implies high fatigue strength. Table 5 shows the result of pulsating tensile fatigue tests (R= min / max =.) in air at room temperature. The fatigue strength has been evaluated at 2 million cycles Physical properties and design values may vary between product forms. Also, different numbers may be used in different design norms due to differences in the fundamental design principles between the norms. Impact toughness. Minimum value for plate up to 3mm, Charpy-V, ft-lbs Table 3 F -4 F -4 F LDX Tensile properties at elevated temperature. Minimum* values, ksi Table 4 YS TS YS TS YS TS YS TS YS TS 2 F F F F * values may differ between product forms and different standards. Listed numbers are representative for ASTM A24 strip/plate with thickness <.4 LDX Code L YS TS Fatigue strength Density lb/in 3.28 and a 5% probability of rupture. The test was made using round polished bars. As shown by the table the fatigue strength of the duplex steels corresponds approximately to the yield strength of the material. Fatigue, pulsating tensile test, ksi. Hot rolled plate, 2mm. Failure probability 5% at 2 million cycles Table 5 actual value for tested specimen 234 Typical values* Table 6 F 2 F 4 F 6 F Modulus of elasticity x 6 psi Poissons ratio.3 4 LDX 244 Linear expansion at (RT T) F x -6 in/in/ F Thermal conductivity Btu/ft/h F Thermal capacity Btu/lb. F Electric resistivity µωcm * values may differ slightly between the different duplex grades RT=Room temperature Code 4 4 Duplex Stainless Steel - 3

3 Corrosion resistance The duplex steels provide a wide range of corrosion resistance in various environments. For a more detailed description of their resistance, see the Outokumpu Corrosion Handbook. A brief description follows below regarding their resistance in different types of environments. Uniform corrosion Uniform corrosion is characterized by a uniform attack on the steel surface that has come into contact with a corrosive medium. The corrosion resistance is generally considered good if the corrosion rate is less than 4 mils/year. Due to their high chromium content, duplex steels offer excellent corrosion resistance in many media. LDX 2 has, in most cases, better resistance than 34 and in some cases similar to. 234 is in most cases equivalent to, while the other more highly-alloyed duplex steels show even better resistance. Sulphuric acid The isocorrosion diagram in sulphuric acid is shown in Figure 2. In sulphuric acid contaminated by chloride ions, 225 Code shows much better resistance than and a similar resistance to that of 94L, Figure LDX L 225 Code Fig. 2 Isocorrosion curves, 4 mils/year, in sulphuric acid H 2 SO 4, weight-% Code Plus Two Boiling Point Curve 225 Code Due to their different alloying levels, the duplex steels show considerable differences in the resistance to pitting and crevice corrosion. LDX 2 has a crevice corrosion resistance between 34 and, 234 is on a level with conventional molybdenum-alloyed steels like, while 225 Code and LDX 244 are similar or maybe even somewhat better than 94L. is generally similar to CPT, F span CPT min - CPT max = less than with 94L and with. CCT, F LDX LDX Code 34L = less than L 94L Hydrochloric acid Stainless steel grades such as 34 and have very limited use in hydrochloric acid because of the risk of uniform and localized corrosion. High-alloyed steels such as, and to some extent also 225 Code can be used in dilute hydrochloric acid, Figure 4. Pitting is normally not a problem in the area below the boundary line in the isocorrosion diagram but crevices should be avoided. Nitric acid In strongly oxidizing acids, e.g. nitric acid, non-molybdenum alloyed steels are often more resistant than the molybdenum alloyed steels. LDX 2 and 234 are good alternatives because of their high chromium content in combination with a low molybdenum content. Pitting and crevice corrosion The resistance to pitting and crevice corrosion increases with the content of chromium, molybdenum, and nitrogen in the steel. This is often illustrated by the pitting resistance equivalent (PRE) for the material, which can be calculated by using the formula: PRE = %Cr x %Mo + 6 x %N. PRE values given for different grades are presented in Table 7. The PRE value can be used to compare the corrosion resistance between different materials. A much more reliable way of ranking steels is according to the critical pitting temperature (CPT). There are several methods available to measure CPT. The electrochemical method, used by Outokumpu, makes it possible to measure the resistance to pitting without interference from crevice corrosion (ASTM G 5). The results are given as the critical pitting temperature, CPT, at which pitting is initiated. The pitting corrosion resistance of the steels in a ground (P32 mesh) condition is shown in Figure 5. The actual value of the as-delivered surface may differ between product forms. 4 94L H 2 SO 4, weight-%, + 2 ppm Cl - Fig. 3 Isocorrosion curves, 4 mils/year, in sulphuric acid containing 2 ppm chloride ions Code 234 Boiling Point Curve HCI, weight-% Fig. 4 Isocorrosion curves 4 mils/year, in hydrochloric acid. When ranking the resistance to crevice corrosion, it is common to measure a critical temperature at which corrosion is initiated in a well-defined solution. The typical critical crevice corrosion temperatures (CCT) measured in 6% FeCl3 + % HCl according to ASTM G 48 Method F, is presented in Figure 6. Different products and different surface finishes may show CCT values that differ from the values shown in the figure LDX 2 Fig. 5 Typical critical pitting corrosion temperatures (CPT) in M NaCl measured according to ASTM G 5 using the Avesta Cell. Test surfaces are wet ground to P32 mesh. CPT may vary with product form and surface finish. PRE values for some austenitic and duplex grades Table 7 Steel grade 234 LDX 244 Duplex 225 Code PRE 34L 8 L 24 LDX EDX LDX L Code L L Austenitic 94L Duplex Austenitic Fig. 6 Typical critical crevice corrosion temperature (CCT) according to ASTM G 48 Method F. Test surfaces dry ground to 2 mesh. CCT varies with product form and surface finish. Stress corrosion cracking Stainless steel can be affected by stress corrosion cracking (SCC) in a chloride containing environment at elevated temperatures. Conventional austenitic stainless steel is particularly vulnerable to stress corrosion cracking while duplex grades are less susceptible to this type of corrosion. Different methods are used to rank stainless steel grades with regard to their resistance to stress corrosion cracking and results may vary depending on the test method as well as the test environment. In Table 8 a comparison is given of the stress corrosion cracking resistance of conventional austenitic stainless steels and duplex stainless steels for a number of accelerated laboratory tests. These methods include immersion tests in several chloride solutions as well as the Wick test (ASTM C 692) which is performed under evaporative conditions. The results show that while duplex stainless steels are not immune under very harsh conditions, such as boiling concentrated magnesium chloride, they withstand stress corrosion cracking under many conditions where conventional austenitic grades are expected to fail. Further SCC results, including data for severe evaporative conditions, are published through our ACOM publications, which are available for download from our website. 4 - Duplex Stainless Steel Duplex Stainless Steel - 5

4 Comparative stress corrosion cracking resistance in accelerated laboratory tests Table 8 Test standard* Test solution Temperature** Load*** 6 - Duplex Stainless Steel ASTM G 36 45% MgCl 3 F (b.p.) 4% CaCl 2 (22 F) 4% CaCl 2 (22 F) YS ASTM G 23 25% NaCl, ph F (b.p.) 25% NaCl 223 F (b.p.) 34L SCC SCC SCC SCC SCC SCC L SCC SCC SCC Possible SCC SCC Possible SCC ASTM C ppm Cl- 22 F YS LDX 2 SCC No SCC No SCC No SCC No SCC No SCC 234 SCC No SCC No SCC No SCC No SCC No SCC LDX 244 SCC SCC Possible No SCC No SCC No SCC No SCC 225 Code Plus SCC No SCC No SCC No SCC No SCC SCC Possible Two SCC No SCC No SCC No SCC No SCC No SCC SCC No SCC No SCC No SCC No SCC No SCC * No standard test method listed, means that the test has been performed based on an Outokumpu internal standard procedure ** b.p. = boiling point *** YS = yield stress, ie indication of loading relative to the specimens measured yield stress. 4-PB = 4 point bend loading fixture SCC = SCC is expected to occur SCC Possible = SCC may occur No SCC = SCC is not expected to occur Sulphide induced stress corrosion cracking In the presence of hydrogen sulphide and chlorides the risk of stress corrosion cracking, at low temperatures, increases. Such environments can exist, for example, in oil and gas production and refining. Duplex grades, such as 225 Code and have demonstrated good resistance. However, caution should be observed regarding conditions with high partial pressure of hydrogen sulphide and where the steel is subjected to high internal stress. 225 Code and are both approved materials according to NACE MRO75/ISO 55 Petroleum and natural gas industries - Materials for use in H 2 S-containing environments in oil and gas production, and all duplex stainless steels have the potential to be used in the less aggressive refining environments following NACE MRO3 guidelines and limitations. Corrosion fatigue The combination of high mechanical strength and very good resistance to corrosion gives duplex steels a high corrosion fatigue strength. S-N curves for 225 Code Plus Two and in synthetic seawater are shown in Figure 7. The corrosion fatigue strength of 225 Code is considerably higher than that of. Intergranular corrosion Due to the duplex microstructure and low carbon content, the duplex steels have very good resistance to intergranular corrosion. The composition of the steel ensures that austenite is reformed in the heat-affected zone after welding. The risk of undesirable precipitation of carbides and nitrides in the grain boundaries is thus minimized. Erosion corrosion Stainless steel in general offers good resistance to erosion corrosion. Duplex grades are especially resistant due to their combination of high surface hardness and good corrosion resistance. Examples of applications where this is beneficial are systems subjected to particles causing abrasive wear, such as pipe systems containing water with sand or salt crystals. Stress amplitude, KSI Number of cycles to failure (N) Galvanic corrosion Galvanic corrosion can occur when two dissimilar metals are connected and one or both metals are in a non-passive state. The galvanic series is dependent not only on the metals involved, but also the environment. The noblest material is protected while the less noble material is more severely attacked. As long as the duplex stainless steels are passive and more noble than other metallic construction materials, meaning that the stainless steel is protected while the corrosion rate of carbon steel, for example, is increased. Galvanic corrosion does not occur between different grades of stainless steels as long as both grades are passive Code Plus Two Fig. 7 Corrosion fatigue of stainless steel in synthetic seawater. Rotating bending test, 5 r/min, with smooth specimens from.6 inch plate. 7 Fabrication Duplex stainless steel is suitable for all forming processes used for stainless steel. The high yield strength compared to austenitic and ferritic stainless steels can impose some differences in forming behavior depending on the forming technique, such as an increased tendency to springback. This point is particularly relevant to forming of any high strength steel. If the forming process is not already selected, it is certainly possible to choose the most suitable one for duplex grades. An excellent interplay between high yield strength, work hardening rate, and elongation promote the use of duplex grades for light weight and cost-efficient applications with complex shapes. The impact of the high strength varies for different forming techniques. Common for all is that the estimated forming forces will be higher than for the corresponding austenitic and ferritic stainless steel grades. This effect will usually be lower than expected since the choice of duplex stainless steel is often associated with thickness reduction. It is important to consider that duplex stainless steel may also be more demanding for the tool materials and the lubricant. Also in this case attention should be given to thickness reduction. Outokumpu, Avesta Research Centre, can support customers in detailed computer analyses of the impact on the forming process when stainless steel grades are to be selected. Cold forming The high strength of the duplex grades is clearly demonstrated when the stress-strain curves of Outokumpu duplex grades are compared with the corresponding austenitic grades, see Figures 8-9. The YS/TS (yield/tensile) ratio also demonstrates a lower deformation hardening rate for duplex grades at higher values of the plastic strain. A sheet material s ability to withstand thinning during forming is demonstrated by the r-value, anisotropic value, in different tensile directions, and the higher the r-value the better, see Figures -. The formability of duplex stainless steel can be characterized in several ways. Figure 3 shows a relative ranking of Outokumpu duplex grades in comparison to a selection of austenitic grades. The ranking resembles the most critical failure mode in sheet forming. In pure drawing, the duplex grades are comparable to austenitic grades as approximately the same limiting drawing ratio can be drawn. r-value Angle to rolling direction LDX Fig. r-values for duplex and austenitic grades with corresponding corrosion resistance. Engineering stress (ksi) Fig. 8 Stress-strain curves for duplex and austenitic grades with corresponding corrosion resistance. Engineering stress (ksi) Fig. 9 Stress-strain curves for duplex and austenitic grades with corresponding corrosion resistance. r-value R p.2 LDX 2 and Engineering Plastic Strain (%) 225 Code Plus Two and LDX 244 LDX Code 94L 94L Engineering Plastic Strain (%) Angle to rolling direction Fig. r-values for duplex and austenitic grades with corresponding corrosion resistance. R m Duplex Stainless Steel - 7

5 Hot forming Hot forming is performed at the temperatures shown in Table 9. It should, however, be observed that the strength of the duplex materials is low at high temperatures and components require support during fabrication. Hot forming should normally be followed by solution annealing and quenching. Heat treatment Temperatures suitable for heat treatment are presented in Table 9. The heat treatment should be followed by subsequent rapid cooling in water or air. This treatment applies for both solution annealing and stress relieving. The latter can in special cases be done at 93-2 F. Further information concerning these operations is available from Outokumpu. Machining Duplex steels are generally more demanding to machine than conventional austenitic stainless steel such as, due to the higher hardness. However LDX 2 has shown excellent machining properties. The machinability can be illustrated by a machinability index, as illustrated in Figure 2. This index, which increases with improved machinability, is based on a combination of test data from several different machining operations. It provides a good description of machinability in relation to. For further information see our Machining Guidelines available for all duplex grades, our dedicated bar product datasheets, or contact Outokumpu. Fig. 2 Machinability index for duplex and some other stainless steels. Characteristic temperatures for hot forming, F Table 9 LDX LDX Code.5.5 Relative machinability LDX 2 LDX Code Welding Duplex steels generally have good weldability and can be welded with methods used for austenitic stainless steel: Shielded metal arc welding (SMAW) Gas tungsten arc welding TIG (GTAW) Gas metal arc welding MIG (GMAW) Flux-cored arc welding (FCW) Plasma arc welding (PAW) Submerged arc welding (SAW) Laser welding Resistance welding High frequency welding Due to the balanced composition, the heat-affected zone obtains a sufficiently high content of austenite to maintain good resistance to localized corrosion. Specific duplex steel grades have slightly different welding parameters. For more detailed information regarding the welding of individual grades, see the Outokumpu Welding Handbook or contact Outokumpu. The following general instructions should be followed: The material should be welded without preheating. The material should be allowed to cool between passes, preferably to below 3 F. To obtain good optimal metal properties in as-welded condition, filler metal shall be used. For LDX 2 reasonably good properties can also be obtained without filler. The recommended arc energy should be kept within certain limits to achieve a good balance between ferrite and austenite in the weld. The heat input should be adapted to the steel grade and be adjusted in proportion to the thickness of the material to be welded. Post-weld annealing after welding with filler is not necessary. In cases where heat treatment is considered, it should be carried out in accordance with the temperatures stated in Table 9, but with the minimum temperature increased 75- F for full dissolution of intermetallic phases in the weld metal. To ensure optimum pitting resistance when using GTAW and PAW methods, an addition of nitrogen in the shielding/ purging gas is recommended. Further information concerning the welding of duplex steels is available in Outokumpu swelding Handbook and in the brochure s How to Weld 225 Code Duplex Stainless Steel. Post fabrication surface treatment In order to restore the stainless steel surface and achieve good corrosion resistance after fabrication, it is often necessary to perform a post fabrication surface treatment. There are different methods available, both mechanical methods (such as brushing, blasting, and grinding) and chemical methods, like pickling. The method applied depends on the particular fabrication surface requirements, i.e. what type of imperfections to be removed, but also on requirements with regard to corrosion resistance, hygienic demands, and aesthetic appearance. Hot forming Solution annealing Stress relief annealing See also Welding. Formability in plane strain LDX LDX Code 34 94L Welding consumables Table Steel grade Consumable Designation Typical composition, % by wt. C Cr Ni Mo N LDX 2 EN 23 7 NL AWS EN 23 7 NL AWS LDX 244 AWS Code AWS AWS also valid for EDX 234, however 2 filler is recommended to match the higher tensile strength and corrosion resistance of EDX 234 Fig. 3 Formability ranking of some duplex and austenitic grades in relation to grade Duplex Stainless Steel Duplex Stainless Steel - 9

6 Outokumpu Products Products LDX LDX Code Hot rolled plate Hot rolled coil and sheet Cold rolled coil and sheet Rod coil Bars Semifinished (bloom, billet, ingot, slab) Pipe DUPROF, high strength profiles See also outokumpu.com/us Table Material Standards Table 2 ISO 55 EN 28-7 Stainless steels - Chemical composition Flat products for pressure purposes - Stainless steels EAM-45-:22/ Pressure equipment Directive 97/23/EC. European approval for materials. EN.462 EN 88-2 EN 88-3 EN 88-4 EN 88-5 EN 272 EN 6-2 ASTM A82 / ASME SA-82 ASTM A24 / ASME SA-24 ASTM 276 ASTM A479 / ASME SA-479 ASTM A789 / ASME SA-789 ASTM A79 / ASME SA-79 ASTM A85 / ASME SA-85 ASTM A928 ASTM A955 ASTM A82 Stainless steels - Corrosion resisting sheet/plate/strip for general and construction purposes Stainless steels - Corrosion resisting semi-finished products/bars/rods/wire/sections for general and construction purposes Stainless steel flat products, technical delivery conditions, steels for construction Stainless steel long products, technical delivery conditions, steels for construction Stainless steel bars for pressure purposes Welded circular steel tubes for mechanical and general engineering purposes - Stainless steel tubes Forged or rolled alloy - steel pipe flanges, forged fittings etc for high temperature service Heat-resisting Cr and Cr-Ni stainless steel plate/sheet/strip for pressure purposes Stainless and heat-resisting steel bars/shapes Stainless steel, bars for boiler and other pressure vessels Seamless and welded duplex stainless steel tubing for general purposes Seamless and welded duplex stainless steel pipe Wrought ferritic, duplex, martensitic stainless steel piping fittings Duplex stainless steel pipe welded with addition of filler metal Deformed and plain stainless steel bars for concrete reinforcement High strength precipitation hardening and duplex stainless steel bolting for special purpose applications VdTÜV WB 48 Ferritisch-austenitischer Walz- und Schmiedestahl,.62 VdTÜV WB 496 Ferritisch-austenitischer Walz- und Schmiedestahl,.4362 VdTÜV WB 556 NACE MR3 / NACE MR75 / ISO 55 NORSOK M-CR 63, MDS 45, MDS D55 ASME Code Case 248- ASME Code Case 263- ASME Code Case 262- ASME Code Case 2637 ASME Code Case N-74 Austenitic-ferritic steel X2CrMnNi2-5-, Material No..462, manufacturer designation: LDX 2 Materials resistant to sulfide stress cracking in corrosive petroleum refining environments Petroleum and natural gas industries - Materials for use in H 2 S-containing environments in oil and gas production SA-82, SA-24, and SA-479 2Cr-5Mn-.5Ni-Cu-N (UNS S32) Austenitic-Ferritic Duplex Stainless Steel/Section VIII, Division Use of UNS S32 Ferritic/Austenitic Stainless Steel Plate, Sheet, Pipe, and Tube/Section IV Use of UNS S32 Ferritic/Austenitic Stainless Steel Plate, Sheet, Pipe, and Tube in the Manufacture of Part HLW Water Heaters and Storage Tanks/Section IV UNS S3225 Plates, Bars, Seamless and Welded Pipe and Tube, Forgings, and Fittings/Section VIII, Division Use of 22Cr-5Ni-3Mo-N (Alloy UNS S3225 Austenitic/Ferritic Duplex Stainless Steel) Forgings, Plate, Welded and Seamless Pipe and Tubing, and Fittings to SA-82, SA-24, SA-789, A79, and SA-85/Section III, Division Class 2 and 3 - Duplex Stainless Steel Duplex Stainless Steel -

7 Working towards forever. 88 EN, Itasca, USA October 24. We work with our customers and partners to create long lasting solutions for the tools of modern life and the world s most critical problems: clean energy, clean water and efficient infrastructure. Because we believe in a world that lasts forever. Information given in this brochure may be subject to alterations without notice. Care has been taken to ensure that the contents of this publication are accurate but Outokumpu and its affiliated companies do not accept responsibility for errors or for information which is found to be misleading. Suggestions for or descriptions of the end use or application of products or methods of working are for information only and Outokumpu and its affiliated companies accept no liability in respect thereof. Before using products supplied or manufactured by the company the customer should satisfy himself of their suitability. 225 Code Plus Two is a trademark of Outokumpu Stainless, Inc. LDX 2, LDX 244, and 254 SMO are trademarks of Outokumpu Stainless. 2 - Duplex Stainless Steel Outokumpu High Performance Stainless 549 West State Road 38, New Castle, IN USA Tel Fax outokumpu.com