Duplex stainless steels are graded for their corrosion performance depending on their alloy content. Today, modern duplex stainless steel can be divided into four groups. This paper describes 18 tensile tests performed on welded specimens made of 3 stainless steel grades. The alloy has outstanding resistance against chlorideinduced stress corrosion cracking and sulphidestress cracking in sourgas conditions. Duplex alloys were originally created to combat corrosion problems caused by chloridebearing cooling waters.
Duplex stainless steel uns s31803 and s32205 general properties ati 2205alloy uns s31803 andor s32205 is a nitrogenenhanced duplex stainless steel alloy. Use of duplex, super duplex and hyper duplex use of duplex, super duplex and hyper duplex stainless steel grades for environments with high content of chloride. The use of duplex stainless steels by the chemical industry has been more limited, but there are now numerous applications where their combination of properties has led to the selection of duplex stainless steels in chemical plants. Applications of duplex stainless steel titan fabricators. S32750 grade s32750 is a super duplex stainless steel containing 25% chromium, 7% nickel and 4% molybdenum. Alloy 32750 is a super duplex stainless steel supplied in the hot worked and solution annealed condition.
Ferralium 255 is a super duplex stainless steel supplied in the cold finished and annealed condition. Sandvik saf 2304 is a lean duplex stainless steel containing no molybdenum and a low nickel content. Duplex stainless steel, famous for its excellent combination of good mechanical properties and high corrosion resistance, is widely used in the industrial fields, such as the production of seawater heat exchangers and the chemical containers for use in the highconcentration chloride environments. Practical guidelines for the fabrication of duplex stainless steels. The duplex family covers a broad range of corrosion resistance, allowing the substitution of standard stainless grades from 304 with lean duplex ur 2202, 904l with ur 2205, up to 6mo with ur 2507 super duplex. The high alloy content and the presence of a ferritic matrix render dss susceptible to embrittlement and loss of mechanical properties, particularly toughness, through prolonged exposure at elevated temperatures. Practical guidelines for the fabrication of duplex stainless. Oil and gas industry equipment, offshore platforms, heat exchangers, process and service water systems, fire. Duplex ss higher nickel and molybdenum 2205, 2003, 2404. Aug 16, 2017 super duplex stainless steel is often employed in the oil and gas industry, heat exchangers, offshore platforms, chemical processing equipment, boilers, and pressure vessels.
When it comes to the fabrication of duplex and super duplex stainless steel, titan has the experience and knowledge to make sure it is engineered, built and inspected to the highest standards. Stainless steels duplex stainless steels properties. An introduction to super duplex stainless steels super duplex stainless steels and their characteristics the firstgeneration duplex stainless steels were developed more than 70 years ago in sweden for use in the sulfite paper industry. If grade 2507 becomes embrittled this can only be rectified by a full solution annealing treatment. Zeron 100 is a highly alloyed super duplex stainless steel for use in aggressive environments. Duplex stainless steel an overview sciencedirect topics. Super duplex stainless steels article pdf available in materials science and technology 88.
Super duplex stainless steel is often employed in the oil and gas industry, heat exchangers, offshore platforms, chemical processing equipment, boilers, and pressure vessels. Duplex grades penn stainless stainless steel plate, sheet. The ferritic and austenitic stainless steel grades have approximately equal proportions i. Historically 317l, 6% molybdenum stainless steels depending on chlorine dioxide residual super duper 7% moly stainless steel, 654smo, for more corrosion resistance 2205 or 2507 and cast equivalents now have wide applicability substitute duplex solid plate or sheet lining for tile lined towers, chests or washers. Duplex stainless steel limitations plate cost duplex stainless steel welding welding is seen as a disadvantage but is probably no more difficult to weld than the austenitics make sure material starts out in the right condition through composition and heat treatment use astm a923 standard and astm a1084 lean for. The increased strength, along with the advanced corrosion resistance of uns s32507 hex bolts over standard stainless steel allows this material to be used for jobs that require a larger load capacity. Stainless steel world november 200747 section sizes or heavy sections with very low heat input. Duplex stainless steels are unrivalled in a large number of applications in the temperature range 50 c to 250 c where a combination of corrosion resistance and mechanical strength is required. Super duplex steel also is known as saf 2507 or super duplex 2507 with uns s32750 and uns s32760 1. This can be attributed to the enhanced levels of chromium, molybdenum and nitrogen found in these materials. This is a duplex alloy stainless steel designed to feature high strength, resistance to pitting, stress corrosion cracking, erosion corrosion and corrosion fatigue, crevice corrosion and strong weldability. Pdf duplex stainless steels microstructure properties and.
The duplex structure gives this family of stainless steels a combination of attractive properties. The word duplex refers to the twophase microstructure of ferritic and austenitic steel grains. Pitting need not be a risk in the zone below the borderline in this figure, but crevices must be avoided. The higher chromium, molybdenum and nitrogen contents result in a pitting resistance equivalent number pren of 40. Sandvik is a key manufacturer and developer for materials used in our systems especially the corrosion resistant ones. Penn stainless inventory now includes duplex 2507, which is a super duplex stainless steel with 25% chromium, 4% molybdenum, and 7% nickel. There is a lot of marketing activity surrounding these grades. Nitrogen is added to the second generation duplex alloys and provides strength and improved weldability. The main difference is that super duplex has a higher molybdenum and chromium content which gives the material greater corrosion resistance than standard duplex grades. Although super duplex grades have good high temperature oxidation resistance, like other duplex stainless steels they suffer from embrittlement if held for even short times at temperatures above 300c.
Duplexsuper duplex stainless steel plate products sandmeyer. For example, customers who have benefited from the performance of sandvik saf 2507, a highly corrosion resistant superduplex steel, are likely to upgrade to. Duplex stainless steels with a pren higher than 40 are extremely resistant to pitting corrosion and are designated as super dss sdss 3. Sandvik saf 2507 superduplex stainless steel sandvik. Super duplex s32750 s32760 super duplex stainless steel. Pdf this paper presents an overview of duplex stainless steels dss with particular emphasis on super dss, i. Although there is a fairly long list of uns grades, only a few of them make the largest part. Duplex s tainless steel are also magnetic, a property. Fatigue and fatigue corrosion resistance of stainless steels are enhanced by the use of duplex grades higher mechanical properties, chromium content and duplex microstructure s32304 316l 317 ln 316l 2. Youll find more information about applications of duplex stainless steel and common grades in the technical resources section on this site. Sandvik duplex stainless steels sandvik materials technology.
For this reason, these alloys are sometimes called super duplex stainless steels. What is the family lean duplex ss lower nickel and no molybdenum 2101, 2102, 2202, 2304 duplex ss higher nickel and molybdenum 2205, 2003, 2404 super duplex 25chromium and higher nickel and molybdenum plus 2507, 255 and z100 hyper duplex more cr, ni, mo and n 2707. Duplex, super duplex, and super austenitic stainless steels for fisher valves high alloy stainless steels for many years, the 300 series stainless steels sst have been the workhorse alloys for corrosive applications. By stocking stainless and super duplex fittings and flanges, mrc global can provide the right product for your corrosive or high temperature application. Super duplex falls under the duplex stainless steel grouping. Penn stainless inventory now includes duplex 2304 uns s32304 in sheet, sheet coil, plate, round bar, processed flat bar and tubular products. Sandmeyer steel company has an extensive inventory of duplex ldx 2101.
The nitrogen serves to significantly improve the corrosion resistance of the alloy. Stainless steel super duplex 2507 hex bolts fasteners. Lean duplex such as 2304, which contains no deliberate mo addition. Super duplex s32750 and super duplex s32760 has 25% chromium 25cr duplex, 4% molybdenum, and 7% nickel also known as x2crnimon25 7 4. For harsher environments, super duplex stainless steels are recommended figure 3.
Practical guidelines for the fabrication of duplex. Super duplex 2507 hex bolts provide extreme strength and corrosion resistance for numerous types of indoor and outdoor applications that require a material that can withstand the elements. Duplex super duplex percent % minimum percent % minimum nitrogen 0. Super duplex grades have enhanced pitting and crevice corrosion resistance when compared with 300series austenitic stainless steels or conventional duplex alloys. Masteel supply a large range of different steels globally, including duplex and super duplex stainless steel. Duplex stainless steel is a type of stainless steel that is composed of grains of two types of stainless steel material, austenitic and ferritic. As a 25% chromium alloy, with significant additions of copper, it offers excellent corrosion resistance in a wide variety of corrosive chemicals including sulphuric, nitric and phosphoric acid. Duplex grades penn stainless stainless steel plate. Superduplex stainless steels sandvik additive manufacturing. Suitable for service in highly corrosive conditions and where high strength is required, the properties of sandvik saf 2507 are being widely used in offshore oil and gas exploration and production and in heat exchangers in petrochemical and chemical processing. The critical crevice corrosion temperature of 2507 and several other highperformance stainless steels are shown above. Duplex and super duplex stainless steels special piping.
They are being offered by all the major stainless steel mills for a number of reasons. Stainless steel super duplex 2507 hex bolts also provide twice the mechanical strength compared to standard. The corrosion of superduplex stainless steel in different types of seawater r francis, g byrne and g warburton. It is a high strength, low cost alternative to standard austenitic grades such as astm 304l and 316l. Duplex stainless steels contain a mixture of austenite and ferrite in their structure, and exhibit characteristics of both phases with higher strength and ductility. Super duplex stainless steel uns s32750 uns s32760. However, the corrosion resistance of the least resistant duplex s tainless steel is greater than that for the most commonly used grades of stainless steel, i. High performance stainless steels nickel institute. Super duplex is an austeniticferritic iron chromium nickel alloy with molybdenum addition. Duplex and super duplex stainless steel flanges 2205 and 2507. Duplex and super duplex stainless steel from masteel. The grade is characterized by very good chloride corrosion resistance, combined with very high mechanical strength. Superduplex falls under the duplex stainless steel grouping.
May 18, 2005 whilst duplex s tainless steel a re considered resistant to stress corrosion cracking, they are not as resistant to this form of attack as ferritic stainless steel. Super duplex stainless like s32750, is a mixed microstructure of austenite and ferrite 5050 which has improved strength over ferritic and austenitic steel grades. Products available from 12120 through our global network of branches. Product bulletin high alloy stainless steels september 2017. Stainless steel is a generic term for a group of corrosion resisting steels containing a minimum of 10. An introduction to superduplex stainless steels corrotherm. The corrosion of superduplex stainless steel in different types of seawater r francis, g byrne and g warburton rolled alloys technology group unit 16, walker industrial park walker road blackburn bb1 2qe uk abstract superduplex stainless steels have been used in seawater systems since 1986 as castings and since 1990 as wrought product. Duplex 2205 is a twophase, ferritic, austenitic 22% chromium, 3% molybdenum, 5 to 6% nickel alloyed stainless steel.
However, due to the introduction of tungsten to some grades of superduplex stainless steel, an element which also improves pitting resistance, a modified form. Issf duplex stainless steels 5 2 standards and chemical compositions applicable standards duplex stainless steel grades are covered by major standards, such as en, iso, astm for a number of products andor applications see appendix 1. Duplex stainless steel super duplex 2507 fine tubes. Duplex steel has a ductile or brittle transition at approximately 50 degrees. Pdf use of duplex, super duplex and hyper duplex use of. There is a conference on the subject of duplex every 23 years where dozens of highly technical papers are presented. Duplex stainless steel grades have a range of corrosion resistance, similar to the range for austenitic stainless steels, i.
Super duplex stainless steel is known to have better stress corrosion, cracking resistance and mechanical properties than any other type of steel. Its combination of properties makes the alloy the optimum choice in many markets. It has the highest resistance to pitting and crevice corrosion of the duplex grades, with high resistance to stress corrosion cracking and very high strength. Whilst duplex s tainless steel a re considered resistant to stress corrosion cracking, they are not as resistant to this form of attack as ferritic stainless steel. Issf duplex stainless steels international stainless steel.
Duplex stainless steel ss 329, uns s32900 plates carbon 0. This stainless steel alloy at least 25% chromium, 7% nickel and 4% molybdenum and can withstand some of the toughest environmental conditions on the planet that produce defects such as corrosion, cracking, erosion, pitting and more. Duplex stainless steel limitations plate cost duplex stainless steel welding welding is seen as a disadvantage but is probably no more difficult to weld than the austenitics make sure material starts out in the right condition through composition and heat treatment. As a super duplex stainless steel, it combines the desirable aspects of both austenitic and ferritic grades. Product bulletin high alloy stainless steels september. Duplex stainless steels have significantly better toughness and ductility than ferritic grades. However, 2507 can be used in dilute hydrochloric acid. Duplex stainless steels are about twice as strong as regular austenitic or ferritic stainless steels. For specific media, lab tests and industrial experience are necessary to refine the relative performance of grades. Austenitic grades are nonmagnetic and in addition to chromium, typically at the 18% level contain nickel which eases the fabrication process and corrosion resistance and are the most widely used group of stainless steels. An introduction to superduplex stainless steels superduplex stainless steels and their characteristics the firstgeneration duplex stainless steels were developed more than 70 years ago in sweden for use in the sulfite paper industry. It is the most widely used duplex stainless steel grade and is characterized by high yield strength, double that of the standard austenitic stainless steel grades.
Lean duplex ss lower nickel and no molybdenum 2101, 2102, 2202, 2304. Nitronic 19d is an example of a duplex stainless steel grade with good. Stainless steel super duplex 2507 hex bolts fastener solutions. The results show that only z100 and 6%mo austenitic alloys.
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