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1.4501, F55, UNS S32760 Super Duplex Stainless Steel has enhanced pitting and crevice corrosion resistance compared with the ordinaryaustenitic or duplex stainless steel types. This is due to the further additions of chromium, molybdenum, and nitrogen to these grades. 1.4501, F55, UNS S32760 Super Duplex Stainless Steel combines high strength and good ductility with outstanding corrosion resistance. With 1.4501, F55, UNS S32760 Super Duplex Stainless Steel having these attribute it is used in a wide range of marine, oil and gas environments. 1.4501, F55, UNS S32760 Super Duplex Stainless Steel is the most common super duplex grade. 1.4501, F55, UNS S32760 Super Duplex Stainless Steel has excellent corrosion resistance to a wide variety of media, with outstanding resistance to pitting and crevice corrosion in seawater and other chloride containing environments, with Critical Pitting Temperature exceeding 50°C. 1.4501, F55, UNS S32760 Super Duplex Stainless Steel has enhanced pitting and crevice corrosion resistance compared with the ordinary austenitic or duplex types. This is due to the further additions of chromium, molybdenum, and nitrogen to these grades. 1.4501, F55, UNS S32760 Super Duplex Stainless Steel combines high strength and good ductility with outstanding corrosion resistance. Providing higher strength than both austenitic and 22% Cr Super Duplex Stainless Steel UNS S32760 (F55) is suited to a variety of applications in industries such as Chemical Processing, Oil & Gas, and Marine environments. Super Duplex Stainless Steel UNS S32760 (F55 / 1.4501) has excellent corrosion resistance to a wide variety of media, with outstanding resistance to pitting and crevice corrosion in seawater and other chloride containing environments, with Critical Pitting Temperature exceeding 50°C. Chemical Composition  C.Cr.Cu.Mn.Mo.N.Ni.P.S.Si.W.0.03%24.00-0.50-1.00%3.00-0.20-6.00-0.035%0.015%1.00%0.50-max26.00%1.00%max4.00%0.30%8.00%maxmaxmax1.00% Minimum Mechanical Properties at Room Temperature (EN10088-3 1.4501, F55, UNS S32760 Super Duplex Stainless Steel 160mm dia max – solution treated) Tensile (UTS)730 – 930 N/mm² 0.2% Proof Stress 530 N/mm² Min Elongation  25% minHardness 290HB Max Impact 100J Super Duplex Stainless Steel Specifications  EN10088-3 UNS S32760 F55 1.4501 Grade X2CrNiMoCuWN25-7-4  ASTM A182 F55 NACE MR01-75 ISI 15156ASTM A276 A314 SAE J405 Norsok MDS D51 D55 D57 D58 Super Duplex stainless steel – with a microstructure of 50:50 austenite and ferrite, the steel has improved strength over ferritic and austenitic steel grades. With a higher than average Molybdenum and Chromium content, the material has greater heat and corrosion resistant qualities.  With reduced production costs when compared with equivalent austenitic and ferritic grades and with greater yield and tensile strength, SuperDuplex is a cost effective solution for the consumer. It is conceivable that material thicknesses for a project may be reduced if SuperDuplex is used, thus reducing cost without compromising quality. Benefits of 1.4501, F55, UNS S32760 Super Duplex Stainless Steel Increased tensile & yield strength Good ductility and toughness SCC resistance Corrosion resistance is better than Duplex Cost effective Applications UNS S32760 is used in the oil and gas industry, on offshore platforms, in heat exchanger, chemical processing equipment, pressure vessels and boilers. Oil and gas industry equipment, Offshore platforms, heat exchangers, process and service water systems, fire-fighting systems, injection and ballast water systems, Chemical process industries, heat exchanger, vessels, and piping, Desalination plants, high pressure RO-plants and seawater piping, Mechanical and structural components, high strength, corrosion-resistant parts, Power industry FGD systems, utility and industrial scrubber systems, absorber towers, ducting, and piping. 1.4501, F55, UNS S32760 Super Duplex Stainless Steel Corrosion Resistance The high chromium and molybdenum content of 1.4501, F55, UNS S32760 Super Duplex Stainless Steel makes it extremely resistant to uniform corrosion by organic acids like formic and acetic acid. 1.4501, F55, UNS S32760 Super Duplex Stainless Steel also provides excellent resistance to inorganic acids, especially those containing chlorides. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

2507 S32750 Super Duplex Stainless Steel is super duplex stainless steel with 25% chromium, 4% molybdenum, and 7% nickel designed for demanding applications which require exceptional strength and corrosion resistance, such as chemical process, petrochemical, and seawater equipment. The steel has excellent resistance to chloride stress corrosion cracking, highthermal conductivity, and a low coefficient of thermal expansion.  Super duplex stainless steel grades have enhanced pitting and crevice corrosion resistance when compared with 300-series austeniticstainless steel or conventional duplex alloys. This can be attributed to the enhanced levels of chromium, molybdenum and nitrogen found in these materials. Alloy 2507 is the most common “super” duplex grade. Usage of Super Duplex 2507 should be limited to applications below 6000 F (3160 C). Extended elevated temperature exposure can reduce both the toughness and corrosion resistance of alloy 2507.The high chromium, molybdenum, and nitrogen levels provide excellent resistance to pitting, crevice, and general corrosion.the duplex structure provides 2507 with exceptional resistance to chloride stress corrosion cracking.  Super Duplex 2507 possesses excellent mechanical properties. Often a light gauge of 2507 material can be used to achieve the same design strength of a thicker nickel alloy. The resulting saving in weight can reduce the overall cost of fabrication. Super Duplex Stainless Steel Corrosion Resistance, The high chromium and molybdenum content of Super Duplex Stainless Steelmakes it extremely resistant to uniform corrosion by organic acids like formic and acetic acid. Super Duplex also provides excellent resistance to inorganic acids, especially those containing chlorides. High resistance to chloride stress corrosion cracking •High Strength •Superior resistance to chloride pitting and crevice corrosion  •Good general corrosion resistance •Suggested for applications up to 6000 F •Low rate of thermal expansion •Combination of properties given by austenitic and ferritic structure •Good weldability and workability 2507 S32750 Super Duplex Stainless Steel Applications: 2507 S32750 Super Duplex Stainless Steel tubes and 2507 S32750 Super Duplex Stainless Steel pipes for production and handling of gas and oil, 2507 S32750 Super Duplex Stainless Steel Pipes in desalination plants, Mechanical and structural components, Power industry FGD systems, 2507 S32750 Super Duplex Stainless Steel Pipes in process industries handling solutions containing chlorides, Utility and industrial systems, rotors, fans, shafts and press rolls where the high corrosion fatigue strength can be utilized, Cargo tanks, vessels, piping and welding consumables for chemical tankers. High-strength, highly resistant wiring. Super Duplex Stainless Steels and their characteristics (1.4410) UNS S32750 2507 Super Duplex Stainless Steel Elbow 90 Degree S32205 S31803(1.4462) Duplex Stainless Steel Pipes S32304 (1.4362) Duplex Stainless Steel Pipes Product Information for 2507 S32750 Super Duplex Stainless Steel PipesSizesStandard TolerancesProductsODWallLengths and/or coilsGradesODWallLengthsPressure &Corrosion Tubing Meets or exceeds requirements forwelded Specification: ASTM-A7891/16″ (1.59 mm) to 4″ (101.6 mm) Metric sizes available0.010″ (0.25 mm) to 0.220″ (5.59 mm)Random or cut lengths up to 40′ (12.2 m) Coils to 1-1/2″ ODSuper Duplex 2507 <1-1/2" (38.1 mm) ±0.005" (0.13 mm) 1-1/2″ (38.1 mm) to 3″ (76.2 mm) ±0.010″ (0.25 mm) 3-1/2″ (88.9 mm) to 4″ (101.6 mm) ±0.015″ (0.38 mm)±10%Randoms up to +2″ (50.8 mm) Cuts +1/8″ (3 mm) -0″ Coils to 80,000′ (24,384 m)Subsea Umbilical Tubing Specifications: ASTM-A789 and ASTM-A7903/8″ (9.53 mm) to 1-1/2″ (38.1 mm)0.039″ (0.99 mm) to 0.125″ (3.18 mm)Cut lengths to 60′ (18.3 m) Coils to 1-1/2″ OD*Super Duplex 2507±0.005″ (0.127 mm)±10%Coils to 80,000′ (24,384 m) Physical Properties of 2507 S32750 Super Duplex Stainless Steel Pipes in the Annealed Condition at -20°F to +100°F Tensile StrengthYield Strength AlloyUNSSpec.psiMPaksipsiMPaksiElongation in 2 in. (min.) %Grain Size Req.Max. HardnessModulus of Elasticity (x106 psi)Mean Coefficient of Thermal Expansion (IN./IN./°F x 10-6)Thermal Conductivity (BTU-in/ ft2-h-°F)Super Duplex 2507S32950A789,A790100,00069010070,0004857020—30.5 Rc———Super Duplex 2507S32750A789, A790116,00080011680,0005508015—32 Rc27.57.298 Composition of 2507 S32750 Super Duplex Stainless Steel PipesGradeSuper Duplex 2507UNS DesignationS32750Carbon (C) Max.0.030Manganese (Mn) Max.1.20Phosphorous (P) Max.0.035Sulphur (S) Max.0.020Silicon (Si) Max.0.80Chromium (Cr)24.0–26.0Nickel (Ni)6.0–8.0Molybdenum (Mo)3.0–5.0Nitrogen (N)0.24–0.32Iron (Fe)Bal.Copper (Cu)0.50Other Elements— Super Duplex 2507 Product RangeAlloyUNS DesignationWerkstoff NR.Specifications*Super Duplex 2507S327501.4410A/SA789, A/SA790 *Note: The specifications noted including ASTM, ASME, or other applicable authorities are correct at the time of publication. Other specifications may apply for use of these materials in different applications. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Duplex Stainless Steel 2304 UNS S32304 is a 23% chromium, 4% nickel, molybdenum-free duplex stainless steel. The Alloy 2304 has corrosion resistance properties similar to 316L. Furthermore, its mechanical properties, i.e., yield strength, are twice those of304L/316L austenitic grades. This allows the designer to save weight, particularly for properly designed pressure vessel applications. Duplex Stainless Steel 2304 UNS S32304, is a lean duplex steel, similar to other duplex steels with it’s high strength and resistance to chlorides stress corrosion cracking, however, due to its lower alloying content it has a lower level of pitting and crevice corrosion resistance (PREN approximately 26). As it contains very little Molybdenum, 2304 is a good economical alternative to 316L in some applications although 2304 is not recommended for use above 300°C. Also known by the the Uranus 35N and SAF2304. The Duplex Stainless Steel 2304 UNS S32304 is particularly suitable for applications covering the -50°C/+300°C (-58°F/572°F) temperature range. Lower temperatures may also be considered, but need some restrictions, particularly for welded structures. With its duplex microstructure, low nickel and high chromium contents, the alloy has improved stress corrosion resistance properties compared to 304 and 316 austenitic grades. With its duplex microstructure and low nickel and high chromium contents, the alloy has improved stress corrosion resistance properties compared to 304 and 316 austenitic grades. uplex stainless steel 2304 successfully passes most of the standard IC test procedures such as ASTM, A262E, and C tests. Its corrosion rate in boiling nitric acid (65%) is higher than that of Alloy 316L. Due to its high yield strength, the alloy performs well in abrasion/corrosion applications. Applications Generally where 304 and 316L are used  Pulp and paper industry (chip storage tanks, white and black liquor tanks, digestors)  Caustic solutions, organic acids (SCC resistance)  Food industry  Pressure vessels (weight savings) Mining (abrasion/corrosion) UNS 32304 Seamless Duplex Stainless Steel Pipe Standards ASTM/ASME………. A240 – UNS S32304 EURONORM………..1.4362 – X2 Cr Ni 23.4 AFNOR……………….Z3 CN 23.04 Az DIN…………………….W. Nr 1.4362  Corrosion Resistance General Corrosion Because of its high chromium content (23%) the corrosion resistance properties of 2304 are almost equivalent to those of 316L. Localized Corrosion Resistance The 23% chromium and 0.1% nitrogen additions explain why 2304 duplex stainless steel behaves much better than Alloy 316L when considering pitting and crevice corrosion resistance. Stress Corrosion Resistance Stress corrosion resistance test results in chloride containing aqueous solutions ((8ppm 02) PH =7, >1000 h, applied stresses higher than the yield strength) show that Alloy 2304 outperforms Alloys 304L and 316L, due to its high chromium additions and low nickel contents.This is a typical feature of duplex stainless steels. Alloy 2205 performs still better than 2304 in similar conditions. Duplex Stainless Steel 1.4362 Composition % according to EN-10216-5:CSiMnPSCrMoNiNCumax. 0,03max. 1,00max. 2,00max. 0,035max. 0,01522,00 – 24,000,10 – 0,603,50 – 5,500,05-0,200,10-0,60 Duplex Stainless Steel S32304 Composition % according to ASTM A789,ASTM A790:CSiMnPSCrMoNiNCumax. 0,03max. 1,00max. 250max. 0,040max. 0,04021,50 – 24,500,50 – 0,603,00 – 5,500,05-0,200,50-0,60 Solution annealing : 950 – 1050 °C (water)  Density 7800kg/m3  Hardness Brinell 290 Max  Tensile Strength @ Break 600 Mpa / 87000psi Min  Tensile Strength @ Yield 400 Mpa / 58000 psi 0.2% offsett  Elongation in 2″ 25% Min  Modulus of Elasticity in tension 200Gpa 28500 ksi Product Information for UNS 32304 Seamless Duplex Stainless Steel Pipe and tubing SizesStandard TolerancesProductsODWallLengths and/or coilsGradesODWallLengthsWelded Heat Exchangers &Condensers Specifications:ASTM-A789 and ASME-SA7890.5″ (12.7 mm) to 4″ (101.6 mm) Metric sizes available0.020″ (0.51 mm) to 0.150″ (3.81 mm)Cut lengths to 60′ (18.3 m)LeanDuplex2304 <0.50" (12.7 mm)  +/-0.005″ (0.13 mm) 0.50″ (12.7 mm) to <1.50" (38.1 mm)  +/-0.005″ (0.13 mm) 1.50″ (38.1 mm) to <3.50" (88.9 mm)  +/-0.010″ (0.25 mm) >3.50″ (88.9 mm) to 4.00″ (101.6 mm)  +/-0.015″ (0.38 mm)+/-15% +/-10%+1/8″  (3 mm) /-0″ Physical Properties of Duplex Stainless Steel 2304 in the Annealed Condition at -20°F to +100°F Tensile StrengthYield Strength AlloyUNSSpec.psiMPaksipsiMPaksiElongation in 2 in. (min.) %Grain Size Req.Max.HardnessModulus of Elasticity (x106 psi)Mean Coefficient of Thermal Expansion (IN./IN./°F x 10-6)Thermal Conductivity (BTU-in/ ft2-h-°F)Lean Duplex 2304 OD=1″ & underS32304A789, A790100,000690100*65,00045058*25—28 Rc, 30* Rc27.57.6180Lean Duplex 2304 OD>1″S32304A789, A79087,000600101*58,00040058*25—28 Rc, 30* Rc27.57.6180 *OD over 1.0″TS>87, YS>58, no hardness requirement 1.0″ OD and under Duplex Stainless Steel 2304 Product Range Alloy UNS Designation Werkstoff NR. Specifications* Lean Duplex 2304 S32304 1.4362 A/SA789, A/SA790 *Note: The specifications noted including ASTM, ASME, or other applicable authorities are correct at the time of publication. Other specifications may apply for use of these materials in different applications Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Ferritic Stainless Steels are, in principle, ferrite at all temperatures. This is achieved by a low content of austenitic forming elements, mainly nickel, and a high content of ferrite forming elements, mainly chromium. Ferritic types, such as 4003 and 4016, are mainly used for household utensils, catering equipment and other purposes where corrosion conditions are not particularly demanding. Steel with high chromium content, such as 4762 with 24% chromium, are used at high temperature where their resistance to sulphurous flue gages is an advantage. However, the risk of 475 °C embrittlement and precipitation of brittle sigma phase in high-chromium steel must always be taken into consideration. Ferritic stainless steel, such as 4521 with extremely low carbon and nitrogen contents, find greatest use where there is a risk of stress-corrosion cracking. Ferritic stainless steels have slightly higher yield strength (Rp 0.2) than austenitic stainless steels, but they have less elongation at fracture. Another characteristic that distinguishes ferritic stainless steel from austenitic material is that ferritic stainless steels have much lower strain hardening.  Ferritic Stainless Steel grades have been developed to provide a group of stainless steel to resist corrosion and oxidation, while being highly resistant to stress corrosion cracking. These steels are magnetic but cannot be hardened or strengthened by heat treatment. They can be cold worked and softened by annealing. As a group, they are more corrosive resistant than the martensitic grades, but generally inferior to the austenitic grades. Like martensitic grades, these are straight chromium steels with no nickel. They are used for decorative trim, sinks, and automotive applications, particularly exhaust systems. Type 430 The basic ferritic stainless steel grade, with a little less corrosion resistance than Type 304. This type combines high resistance to such corrosives as nitric acid, sulfur gases, and many organic and food acids. Type 405 Has lower chromium and added aluminum to prevent hardening when cooled from high temperatures. Typical applications include heat exchangers. Type 409 Contains the lowest chromium content of all stainless steels and is also the least expensive. Originally designed for muffler stock and also used for exterior parts in non-critical corrosive environments. Type 434 Has molybdenum added for improved corrosion resistance. Typical applications include automotive trim and fasteners. Type 436 Type 436 has columbium added for corrosion and heat resistance. Typical applications include deep-drawn parts. Type 442 Has increased chromium to improve scaling resistance. Typical applications include furnace and heater parts. Type 446 Contains even more chromium added to further improve corrosion and scaling resistance at high temperatures. Especially good for oxidation resistance in sulfuric atmospheres. Ferritic Stainless Steels, which are part of the 400 series of stainless alloys, have chromium as their major alloying element and are typically low in carbon content. Ductility and formability are less than that of the austenitic grades. The corrosion resistance is comparable to that of the austenitic grades in certain applications. Thermal conductivity is about half that of carbon steels. Ferritic stainless steel are magnetic, they generally have good ductility and can be welded or fabricated without difficulty. These grades can be processed to develop an aesthetically pleasing, bright finish and, hence, are sometimes used for automotive trim and appliance molding. They also find use in functional applications where cost is a major factor, e.g., automotive exhaust systems, catalytic converters, radiator caps, and chimney liners. These grades can be hardened by cold rolling, but cannot be hardened as much as the austenitic alloys. Stainless Steel – FerriticAlloy (UNS Designation) End UseComposition nominal wt%SpecificationsDensity lb/in3 (g/cm3)Tensile Strength ksi. (MPa)0.2% Yield Strength ksi. (MPa)Elong- ation %Hardness Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

ASTM A789 covers standard requirements for grades of nominal wall thickness, stainless steel tubes for services requiring general corrosion resistance, with particular emphasis on resistance to stress corrosion cracking. These steels are susceptible to embrittlement if used for prolonged periods at elevated temperatures. Heat and product analyses shall be performed wherein the steel shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, nitrogen, copper, and others. All stainless steel tubes shall be furnished in the heat-treated condition in accordance with the specified temperature and quenching conditions. ​ When the final heat treatment is in a continuous furnace, or when heat treated condition is obtained directly by quenching after hot forming, the number of stainless steel tubes of the same size and from the same heat in a lot shall be determined from the prescribed sizes of the stainless steel tubes. The material shall conform to the prescribed tensile and hardness properties. Mechanical tests such as tension tensile strength test, flaring test for seamless stainless steel tubes, stainless steel flanges test for welded stainless steel tubes, hardness test, and reverse flattening test shall be performed on the stainless steel tubes. Each tube shall also be subjected to the nondestructive electric test or the hydrostatic test. This covers grades of nominal wall thickness, stainless steel tubes for services requiring general corrosion resistance, with particular emphasis on resistance to stress corrosion cracking. These steels are susceptible to embrittlement if used for prolonged periods at elevated temperatures. The values stated in either inch-pound units or SI units are to be regarded separately as standard. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. Within the text, the SI units are shown in brackets. The inch-pound units shall apply unless the M designation of this specification is specified in the order. 2. Referenced Documents A1016/A1016M Specification for General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel Tubes. A480/A480M Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plates, Sheets, and Bars. E527 Practice for Numbering Metals and Alloys in the Unified Numbering System (UNS). SAE J1086 Practice for Numbering Metals and Alloys (UNS). Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Super ferritic Stainless Steel has a structure and properties similar to the common ferritic alloys, but they contain enhanced levels of chromium and molybdenum to increase their resistance to high temperature and corrosive environments such as seawater.Stainless Steel – SuperferriticAlloy (UNS Designation) End UseComposition nominal wt%SpecificationsDensity lb/in3 (g/cm3)Tensile Strength ksi. (MPa)0.2%Yield Strength ksi. (MPa)Elong- ation %HardnessS44735 Welded stainless steel tubing used in seawater and other applications requiring extreme resistance to chloride pitting, crevice corrosion and stress corrosion crackingC 0.03 max, Mn 1.0 max, P 0.04 max, S 0.03 max, Si 1.0 max, Cr 28.0-30.0, Ni 1.0 max, Mo 3.6-4.2, N 0.045 max, (Ti+Cb) 0.2-1.0, (Ti+Cb) 6x(C+N) min, Fe BalanceASTM A2400.277 (7.67)80 min (550 min)60 min (415 min)18 min25 Rockwell C maxS44627 Solenoid valves, Pressure vessels, Coker components, Heat exchanger stainless steel tubing, Air preheaters, Heat recuperatorsC 0.01 max, Mn 0.4 max, Si 0.4 max, Cr 25.0-27.5, Ni 0.5 max, Mo 0.75-1.5, N 0.015 max, Cu 0.2 max, Cb 0.05-0.2, (Ni+Cu) 0.5 max, Fe BalanceASTM A-240 ASME SA-2400.280 (7.76)65 min (450 min)40 min (275 min)22 min Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

ASTM A790 covers seamless and straight-seam welded duplex stainless steel pipe for general corrosive service, with particular emphasis on resistance to stress corrosion cracking. The duplex stainless steel pipe shall be made by the seamless or an automatic welding process, with no addition of filler metal in the welding operation. Heat analysis shall be made to determine the percentages of the elements specified. Tension tests, hardening tests, flattening tests, hydrostatic test and nondestructive electric tests shall be made to conform to the specified requirements. This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. This specification covers seamless and straight-seam welded ferritic/austenitic stainless steel pipe intended for general corrosive service, with particular emphasis on resistance to stress corrosion cracking. These steel are susceptible to embrittlement if used for prolonged periods at elevated temperatures. Optional supplementary requirements are provided for welded ferritic/austenitic stainless steel pipe when a greater degree of testing is desired. These supplementary requirements call for additional tests to be made and, when desired, one or more of these may be specified in the order. Appendix X1 of this specification lists the dimensions of welded and seamless stainless steel pipe complies with all other requirements of this specification. The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. The inch-pound units shall apply unless the M designation of this specification is specified in the order. The dimensionless designator NPS (nominal duplex stainless steel pipe size) has been substituted in this standard for such traditional terms as nominal diameter, size, and nominal size. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The surface of a metallographic stainless steel tubes are prepared by polishing, grinding,and etching. After preparation, it is often analyzed using optical or electron microscopy. Using only metallographic techniques, a skilled technician can identify stainless steel material properties. Mechanical preparation is the most common preparation method. In a series of steps, successively finer abrasive particles are used to remove material from the sample surface until the desired surface quality is achieved. Many different machines are available for doing this grinding and polishing, able to meet different demands for quality, capacity, and reproducibility. A systematic preparation method is easiest way to achieve the true structure. Sample preparation must therefore pursue rules which are suitable for most materials. Different materials with similar properties (hardness and ductility) will respond alike and thus require the same consumables during preparation. Metallographic stainless steels are typically “mounted” using a hot compression thermosetting resin. In the past, phenolic thermosetting resins have been used, but modern epoxy is becoming more popular because reduced shrinkage during curing results in a better mount with superior edge retention. A typical mounting cycle will compress the specimen and mounting media to 4,000 psi (28 MPa) and heat to a temperature of 350 °F (177 °C). When specimens are very sensitive to temperature, “cold mounts” may be made with a two-part epoxy resin. Mounting a specimen provides a safe, standardized, and ergonomic way by which to hold a sample during the grinding and polishing operations. macro etched copper discard, After mounting, the specimen is wet ground to reveal the surface of the metal. The specimen is successively ground with finer and finer abrasive media. Silicon carbide abrasive paper was the first method of grinding and is still used today. Many metallographers, however, prefer to use a diamond grit suspension which is dosed onto a reusable fabric pad throughout the polishing process. Diamond grit in suspension might start at 9 micrometres and finish at one micrometre. Generally, polishing with diamond suspension gives finer results than using silicon carbide papers (SiC papers), especially with revealing porosity, which silicon carbide paper sometimes “smear” over. After grinding the specimen, polishing is performed. Typically, a specimen is polished with a slurry of alumina, silica, or diamond on a napless cloth to produce a scratch-free mirror finish, free from smear, drag, or pull-outs and with minimal deformation remaining from the preparation process. After polishing, certain microstructural constituents can be seen with the microscope, e.g., inclusions and nitrides. If the crystal structure is non-cubic (e.g., a metal with a hexagonal-closed packed crystal structure, such as Ti or Zr) the microstructure can be revealed without etching using crossed polarized light (light microscopy). Otherwise, the microstructural constituents of the specimen are revealed by using a suitable chemical or electrolytic etchant. A great many etchants have been developed to reveal the structure of metals and alloys, ceramics, carbides, nitrides, and so forth. While a number of etchants may work for a given metal or alloy, they generally produce different results, in that some etchants may reveal the general structure, while others may be selective to certain phases or constituents. Macro Examination Macroetching is the procedure in which a specimen is etched and evaluated macro structurally at low magnifications. It is a frequently used technique for evaluating steel products such as stainless steel tubes, billets, bars, flanges, and pipe fittings. There are several procedures for rating a steel specimen by a graded series of photographs showing the incidence of certain conditions and is applicable to carbon and low alloy steels. A number of different etching reagents may be used depending upon the type of examination to be made. Steels react differently to etching reagents because of variations in chemical composition, method of manufacturing, heat treatment and many other variables.  Macro-Examinations are also performed on a polished and etched cross-section of a welded material. During the examination, a number of features can be determined including weld run sequence, important for weld procedure qualifications tests. As well as this, any defects on the sample will be assessed for compliance with relevant specifications. Slag, porosity, lack of weld penetration, lack of sidewall fusion and poor weld profile are among the features observed in such examinations. It is normal to look for such defects either by standard visual examination or at magnifications of up to 50X. It is also routine to photograph the section to provide a permanent record. This is known as a photomacrograph. Micro Examination This is performed on samples either cut to size or mounted in a resin mold. The samples are polished to a fine finish, normally one micron diamond paste, and usually etched in an appropriate chemical solution prior to examination on a metallurgical microscope. Micro-examination is performed for a number of purposes, the most obvious of which is to assess the structure of the material. It is also common to examine for metallurgical anomalies such as third phase precipitates, excessive grain growth, etc. Many routine tests such as phase counting or grain size determinations are performed in conjunction with micro-examinations. Weld Examination Metallographic weld evaluations can take many forms. In its most simple form, a weld deposit can be visually examined for large scale defects such as porosity or lack of fusion defects. On a micro scale, the examination can take the form of phase balance assessments from weld cap to weld root or a check for non-metallic or third phase precipitates. Examination of weld growth patterns is also used to determine reasons for poor mechanical test results. For example, an extensive central columnar grain pattern can cause a plane of weakness giving poor charpy results. Case Depth Case hardening may be defined as a process for hardening a ferrous materials in such a manner that the surface layer (known as the case), is substantially harder than the remaining materials (known as the core). This process is controlled through carburizing, nitriding, carbonitriding, cyaniding, induction and flame hardening. The chemical composition, mechanical properties, or both, are effected by these practices. Methods for determining case depth are either chemical, mechanical or visual and should be selected on the basis of specific requirements. Decarburization Measurement This method is designed to detect changes in the microstructure, hardness, or carbon content at the surface of the steel sections due to carburization. The depth is determined as the depth where a uniform microstructure, hardness, or carbon content, typical of the interior of the specimen is observed. This method will detect surface losses in carbon content due to heating at elevated temperatures, as in hot working or heat treatment. Coating / Plating Evaluation (ASTM B487, ASTM B748) A coating or plating application is used primarily for protection of the substrate. The thickness is an important factor in the performance of the coating or plating. A portion of the specimen is cut, mounted transversely, a prepared in accordance with acceptable or suitable techniques. The thickness of the cross section is measured with an optical microscope. When the coating or plating is thinner than .00020″, the measurement should be taken with the aid of the scanning electron microscope. Cross-sectioned metallographic examinations of substrates with platings, surface evaluations, thickness measurements, weight per volume, and even salt spray testing can aid in the evaluation of platings. Surface Evaluation Surface inspection includes the detection of surface flaws and he measurement of surface defects and roughness. One method includes the use of a laser light. When the scattered light is reflected off the surface of a sample, it can be analyzed and measure. Another method is the use of a motorized stylus (profilometer). The stylus is placed on the surface and the texture of the material is measured in micro-inches or millimeters. Grain Size Determination In order to establish a scale for grain size, ASTM E112 shows charts with outline grain structures at various dimensions. This has led to a universally accepted standard by which grain sized range form 1 (very coarse) to 10 (very fine). A material’s grain size is important as it affects its mechanical properties. In most materials, a refined grain structure gives enhanced toughness properties and alloying elements are deliberately added during the stainless steel making process to assist in grain refinement. Grain size is determined from a polished and etched sample using optical microscopy at a magnification of 100X. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The Ferritic Stainless Steel Grades Comparison Table is intended to relate former BS, EN, German and Swedish grade designations to the current EN steel numbers, AISI grades and UNS numbers. The table is based on the ‘wrought’ ie long products (stainless steel bars etc), pipe products (stainless steel pipes etc) stainless steel numbers published in EN 10088 and related standards.  Casting products use different composition and so have their own stainless steel numbers in EN 10283. The related castings grades in both EN 10283 and BS 3100 are included in the table. The Chemical ‘Composition’ is intended to represent the composition only. This does not show the specified or typical compositions of commercially available steel. Specified ranges for the wrought European grades can be found in either the EN 10088-2 or EN 10088-3 tables. Most of the specified ranges for the ‘BS’ grades can be found in the BS 1449 or BS 970 tables. The castings grades specified ranges can be found in the EN 10283 or BS 3100 tables. These are comparisons only and cannot be assumed to be direct equivalent grades. The data given is not intended to replace that shown in inpidual standards to which reference should always be made. Ferritic Stainless Steel Grades Comparison Table EN 10088Common NamesBS WroughtAISIUNSENGerman DINSSEN 10283BS CastingChemical Composition..........CCrNiMoOthers1.4000–403S17410SS41008–X6Cr132301––0.08x12–––1.4002–405S17405S40500–X6CrAl13–––0.08x12––0.2 Al1.40033Cr12––S41050–X2Cr11–––0.03x110.5––1.4016–430S17430S4300060X6Cr172320––0.08x17–––1.4113–434S17434S43400–X6CrMo17-1–––0.08x17–1–1.450918CrCb–441S44100–––––0.015x18––NbandTi1.4510430Ti–439S43035–X6CrTi17–––0.05x17––0.6 Ti1.4511––430Nb––X6CrNb17–––0.05x17––0.6 Nb1.4512–409S19409S40900–X6CrTi12–––0.03x11––0.5 Ti1.4520–––––X2CrTi17–––0.025x17––0.5 Ti:0.015N1.4521––444S44400–X2CrMoTi18-2–––0.025x17–20.6 Ti1.4526––436S43600–X2CrMoNb17-1–––0.08x17–1.20.6 Nb1.4592–––––X2CrMoTi2-4–––0.025x28–4.00.6 Ti1.4605–––––X2CrAlTi18-2–––0.03x17––0.6 Ti:2.0 Al Note Chemical composition figures are intended to be representative of the grade, not typical. ‘x’ indicates a maximum Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Pitting resistance equivalent numbers (PREN) are a theoretical way of comparing the pitting corrosion resistance of various types of stainless steel, based on their chemical composition. The PREN (or PRE) numbers are useful for ranking and comparing the different grades, but cannot be used to predict whether a particular grade will be suitable for a given application, where pitting corrosion may be a hazard. Actual or specified range composition can be used and usually involve chromium, molybdenum and nitrogen in the calculations. Tungsten also appears in some versions of the calculation. In some industries, notably the oil and gas sector, specifications may place tighter restrictions on the PREN for specific grades than that implied by the minimum composition of the grade defined in EN or ASTM Standard. Affect of alloying elements on pitting resistance These are ‘linear’ formulas, where the molybdenum and nitrogen levels are ‘weighted’ to take account of their strong influence on pitting corrosion resistance. They typically take the form: PREN = Cr + m Mo + n N where ‘m’ and ‘n’ are the factors for molybdenum and nitrogen. The most commonly used version of the formula is: PREN = Cr + 3.3Mo + 16N Some formulas weight nitrogen more, with factors of 27 or 30, but as the actual nitrogen levels are quite modest in most stainless steel, this does not have a dramatic effect on ranking. Tungsten is also included in the molybdenum-rating factor to acknowledge its affect on pitting resistance in the tungsten bearing super duplex stainless steel types, for example 1.4501. A modified formula is then used: PREN = Cr + 3.3(Mo +0.5W) + 16N Calculated pitting resistance numbers Nitrogen ranges are not specified in standards such as EN 10088-1 for all but specific grades, such as 1.4311 (304LN), 1.4406 (316LN) austenitic stainless steel. In contrast all the duplex stainless steel grades have specified nitrogen ranges. It can then be misleading to use just specified ranges as the residual nitrogen in commercially produced austenitic will benefit the pitting resistance. The table below shows a range of calculated PREN values for comparison. A full theoretical range is shown, using a combination of the lowest and highest specified values for a selection of ferritic, austenitic and duplex stainless steel grades. The values are rounded for convenience of display. The PREN values for commercially available grades will of course lie somewhere between these minimum and maximum values and so commercially available steels in grades S32750 1.4410, 1.4501 and 1.4507 are often stipulated to have actual PREN values over 40. Grades with a PREN of 40 or more are known as ‘super’ austenitic or ‘super’ duplex stainless steel types, depending to which basic family they belong. PREN = Cr + 3.3Mo + 16N Tungsten (W) is known to have an effect on the pitting resistance and for some grades a modified formula is used: PREN = Cr + 3.3(Mo +0.5W) + 16N GradeTypeCrMoNPRENFerritics Stainless Steel1.4003–10.5-12.5NS0.030 max10.5-13.01.401643016.0-18.0NSNS16.01.411343416.0-18.00.9-1.4NS19.0-22.61.450944117.5-18.5NSNS17.5-18.51.452144417.0-20.01.8-2.50.030max23.0-28.7Austenitics Stainless Steel1.430130417.0-19.5NS0.11max17.0-20.81.4311304LN17.0-19.5NS0.12-0.2218.9-23.01.4401/4316/316L16.5-18.52.0-2.50.11max23.1-28.51.4435316L (2.5% min Mo)17.0-19.02.5-3.00.11max25.3-30.71.4406316LN16.5-18.52.0-2.50.12-0.2225.0-30.31.4539904L19.0-21.04.0-5.00.15max32.2-39.91.4563Sanicro 2824.0-26.03.0-4.00.11max35.9-43.01.4547254SMO19.5-20.56.0-7.00.18-0.2542.2-47.61.45291925hMo19.0-21.06.0-7.00.15-0.2541.2-48.11.45654565S24.0-26.04.0-5.00.30-0.6042.0-52.1Duplex Stainless Steel1.40621220222.00.40.2026.51.41622101LDX21.0-22.00.1-0.80.20-0.2524.5-28.61.4362SAF 230422.0-24.00.1-0.60.05-0.2023.1-29.21.4462SAF 220521.0-23.02.5-3.50.10-0.2230.8-38.11.4410SAF 250724.0-26.03.0-4.00.24-0.35> 4021.45012Zeron 100224.0-26.03.0-4.00.20-0.30> 4021.45072Ferrinox 255224.0-26.03.0-4.00.20-0.30> 402 The nearest AISI grade is shown, where appropriate, otherwise a typical trade name used by some of manufacturers is shown. NS – Not specified 1 Typical composition only available 2 The “super duplex” stainless steels in particular are subject to tighter restrictions on PREN than that implied by the minimum composition of the EN grade. For example, the equivalent ASTM grade or the specifications of the oil and gas industry e.g. NORSOK or NACE typically require a minimum of PREN =40. K03ArcelorMittal Stainless UK Ltd2101LDXOutokumpu Ltd904LOutokumpu Ltd254SMO 4565SOutokumpu LtdSAF 2304, SAF 2205, SAF 2507, Sanicro 28Sandvik Steel UKZeron 100Rolled Alloys Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

High content of alloying elements, the price is relatively high, generally free of nickel ferrite. In summary, you can generally see the use of DSS performance and process performance of the general picture that, with its superior mechanical and corrosion-resistant comprehensive performance to win the favor of users, both to save weight, it has become an excellent resistance to save investment Corrosion Engineering. ​ 1. yield strength than conventional austenitic stainless steel more than twice as high, and has a plastic molding needs adequate toughness. Use of duplex stainless stee tank or pressure vessel wall thickness less than the usual 30-50% austenite is beneficial to reduce costs. 2. has excellent resistance to stress corrosion ability to break even with the lowest amount of duplex stainless steel alloy has a higher resistance than the austenitic stainless steel Stress Corrosion Cracking of capacities, particularly in chloride ion environments. Austenitic stainless steel stress corrosion is a common problem difficult to resolve outstanding. 3. In many applications the most common medium of 2205 duplex stainless steel corrosion resistance than the average of316L stainless steel, and super Duplex stainless steel with high corrosion resistance, then a number of media, such as acetic acid, formic acid, etc. can even replace the high-alloy austenitic stainless steel, and even corrosion resistant alloy. 4. has a good resistance to localized corrosion, with the austenitic stainless steel alloy content rather than its resistance to corrosion and fatigue corrosion and wear better than the austenitic stainless steel. 5. than the linear expansion coefficient of austenitic stainless steel is low, and carbon steel close fit with the carbon steel connections, has important engineering significance, such as the production of composite boards or lining and so on.  6. in terms of dynamic load or static load conditions, than the austenitic stainless steel has a higher energy absorption capacity, which structural parts cope with unexpected incidents such as collisions, explosions, etc., have obvious advantages of duplex stainless steel, are of practical value. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Why have stainless steel rust? When the stainless steel surface of brown rust (points), people is not great surprise of stainless steel, and steel may be a problem. In fact, this is a lack of understanding of stainless steel. Stainless steel Kind of one-sided view of the error. Stainless steel under certain conditions will be rusty. Stainless steel has had in acid, alkali and salt corrosion medium capacity — that is corrosion resistance. However, the size of its corrosion resistance is the steelitself, with its chemical composition, plus each state, using the conditions and dry cleaning of the atmosphere, there is absolutely excellent anti-corrosion ability, but will move it to the waterfront, in the presence of a large number of salt sea mist, steel is good. So it is not any kind of stainless steel capability in any environment not rust corrosion. Stainless steel is formed by the surface layer of very thin and fine for the continued infiltration of strong and continue tooxidation, and access to anti-corrosion ability. If there is some reason, this film was the constant destruction, infiltration of air or liquid or metal will continue to keep in isolation of the iron atom out of the formation of oxygen continuously loose rust. A kind of stainless steel in a number of media have good corrosion resistance, but in some other medium, but may occur due to low chemical stability and corrosion. So, a stainless steel corrosion can not have all media. Metal corrosion, according to management mechanism can be pided into special corrosion, chemical corrosion and electrochemical corrosion of metal corrosion in engineering practice, most belong to electrochemical corrosion. The main form of corrosion of stainless steel corrosion (surface corrosion), pitting corrosion, crevice corrosion and stress corrosion. Corrosion Corrosion is galvanic corrosion of metal surfaces all media phenomenon of corrosion. According to different requirements resorted to different indicators, generally pided into two main categories: 1. Stainless steel refers to the atmosphere and weak corrosion of steel corrosion medium. Corrosion rate of less than 0.01mm is “totally corrosion”; corrosion rate of less than 0.1mm / year, considered “corrosion” of.  2. Corrosion of steel refers to a variety of strong corrosive medium to corrosion of steel. Pitting corrosion Pitting corrosion is the metal surface in the most non-corrosive or highly corrosion of mild and scattered occurrence of localized corrosion, corrosion point of common size is less than 1.00mm, the depth is often greater than the surface aperture, light shallow pits those who have serious even the formation of perforation. Crevice corrosion Crevice corrosion is occurring in the metal component crevice corrosion pits dot-like view, this is a localized corrosion. Intergranular corrosion Intergranular corrosion is a selective corrosion damage, it is with the Department, is the microscopic scale localized corrosion, while the macro is not necessarily local. Stress corrosion cracking (SCC) Stress corrosion cracking is to bear the stress of the alloy in the corrosive environment because of strong expansion of the alternate failure pattern of a generic term. General corrosion General corrosion is used to describe the alloy surface are spoon way to compare the corrosion occurred in the terminology. In case of general corrosion, the village gradually thinner material because of corrosion, corrosion or failure. Stainless steel in strong acid and alkali corrosion may be present round. Comprehensive failure caused by corrosion of the problem is not how worrying, because, this corrosion can often be a simple soak test or inspection Fushi’s literature information predict it. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)