Duplex steel has a ductile or brittle transition at approximately 50 degrees. Classification and mechanical properties specification average hardness minimum tensile strength minimum yield strength minimum elongation astm a890 grade 1b 245 265 hbn 100,000 psi 689 mpa 70,000 psi 483 mpa 16%. The major problem in ferritic stainless steels is the tendency to embrittlement, aggravated by various causes. Welding metallurgy of duplex austeniticferritic stainless. This precipitation happens because the carbides are insoluble at these temperatures. There are three primary classifications within the highperformance stainless steels. While most have uns numbers, some are also referred to by their chromium and nickel contents. Stainless steel, a class of ferrous alloys, is wellknown for their resistance to corrosion, creep and high temperature applications. Stainless steels duplex stainless steels properties.
Practical guidelines for the fabrication of duplex stainless steels. The weld solidification of duplex stainless steel is entirely ferritic. Ironchromiumnickel grades corresponding to both standard aisi 300series alloys and modified versions of these alloys. Mcgraw hill 1977 tool steels roberts and cary, edition 4, asm, 1980 ferrous physical metallurgy a. People like this webinar because it provides a simple framework for understanding the differences between alloys. Such alloys, which are based on type 304 188 stainless steel, as shown in fig. There is a conference on the subject of duplex every 23 years where dozens of highly technical papers are presented.
In order for the carbide to precipitate, it must obtain chromium from the surrounding metal. It is a high strength, low cost alternative to standard austenitic grades such as astm 304l and 316l. Lean duplex, 2304 s32304, which contain little or free of mo fe23cr4ni0. Grains and grain size control, role of deformation and deformation processing 4. Duplex stainless steels are graded for their corrosion performance depending on their alloy content. Precipitationhardenable stainless steels are chromiumnickel alloys containing.
Duplex stainless steel castings these grades offer a combination of higher strengths and good corrosion resistance, especially in sea water applications. Good welding specifications usually detail requirements for processes, consumables, corrosion testing, etc, etc to a level that accounts for the absence of subsequent heat treatment. Super duplex stainless steel is known to have better stress corrosion, cracking resistance and mechanical properties than any other type of steel. However, 2507 can be used in dilute hydrochloric acid. Evaluation of the microstructure and localized corrosion. Duplex s tainless steel are also magnetic, a property. The term duplex steel is generally used to define steels with a twophase structure. Due to increasing demand of powder metallurgy compenents made. Pwht of duplex stainless steels metal and metallurgy. Introduction to stainless steels asm international. Super duplex stainless steels article pdf available in materials science and technology 88. Pitting need not be a risk in the zone below the borderline in this figure, but crevices must be avoided. Duplex stainless steel 2205 alloy offers extensive resistance to the local corrosion factors like intergranular, pitting and crevice corrosion. Chlorideinduced stress corrosion cracking of powder.
Effect of composition profiles on metallurgy and corrosion. Duplex stainless steel castings investment sand foundry. The physical metallurgy of duplex stainless steels english nilsson, j. Practical guidelines for the fabrication of duplex. Basing ourselves on these studies, we may outline the major steps as follows. These alloys also offer good toughness at lower temperatures and the higher strengths provide erosion resistance. During welding, control of heat input is essential and, in some cases, also a postweld heat treatment. Microstructure and properties of modern pm super duplex. It offers outstanding resistance to the chloride ion stress cracking at temperature ranges to 150oc. Lean duplex such as 2304, which contains no deliberate mo addition. Search on practical guidelines for the fabrication of duplex stainless steel. Chemical bonding, atom size, lattices, crystals and crystalline defects, solid solutions, alloying and microstructures 3.
It has been written primarily from a european perspective and may not fully reflect the practice in other regions. Stainless steel is the term used to describe an extremely versatile family of. Issf duplex stainless steels international stainless steel. Stainless steel metallurgy industrial metallurgists. In presented study duplex stainless steels were obtained through powder metallurgy starting from austenitic. They exhibit characteristics of both phases with higher strength and ductility. Introduction worldwide, in industry, in business and in the home, metals called stainless steels are used daily. Based primarily on microstructure, five stainless steel types are recognized. Standard 2205 s32205 for more than 80% of duplex use fe23cr5. Precipitation of intermetallic secondary phases in duplex stainless steels is a well. Sandvik saf 2304 is a lean duplex stainless steel containing no molybdenum and a low nickel content. Duplex stainless steels dss with austeniteferrite microstructure are high strength.
Properties of duplex stainless steels made by powder metallurgy. Wilfleys cd4mcun offers superior mechanical properties to 300 series stainless steels with similar corrosion properties. If less nickel is added to a chromium steel, about four or five percent, a duplex structure, a mixture of austenite. The welding metallurgy of duplex stainless steels, proc conf duplex stainless steels, vol. The duplex structure gives this family of stainless steels a combination of attractive properties. The stainless steels in each family have general similarities, but there is also a wide range of corrosion resistance and other characteristics. Handbook of stainless steels, peckner and bernstein eds. Properties of duplex stainless steels made by powder. Using its metallurgical expertise, sandvik is continu ing to achieve breakthroughs in duplex stainless steels, adding more specialized, higher performance. The stainless steel family a short description of the various grades of stainless steel and how they fit into distinct metallurgical families. Duplex stainless steels contain more chromium and less nickel than 300series and typically include nitrogen as an additional austenite stabilizer and molybdenum for corrosion resistance.
Due to the lower alloying content, duplex stainless steels can be lower in cost, especially in times of high alloy surcharges. Pdf duplex stainless steels microstructure properties and. Applications of duplex stainless steel duplex 2205 stainless steel tubeside and 304 ss shellside preheaters high pressure shell and tube heat exchanger titan gained its reputation in the precision welding of complex and difficult to handle corrosionresistant alloys. Selected grades of duplex stainless steel castings and their welds, in comparison with their wrought counterparts, were evaluated, regarding corrosion. General physical metallurgy concepts common to all alloy systems 2. The welding of stainless steels 2 1 general information on stainless steels 1. Welding metallurgy and weldability of stainless steels, the first book in over twenty years to address welding metallurgy and weldability issues associated with stainless steel, offers the most uptodate and comprehensive treatment of these topics currently available. In metallurgy, stainless steel, also known as inox steel or inox from french inoxydable inoxidizable, is a steel alloy, with a minimum of 11% chromium content by mass and a maximum of 1. This paper presents an overview of duplex stainless steels dss with particular emphasis on super dss, i.
Powder metallurgical duplex austeniticferritic stainless. Introduction to stainless steel industrial metallurgists. Duplex stainless steels are not covered by the standard aisi 200, 300, or 400 groups. Duplex stainless steel, markets and applications, chemistries, metallurgy, mechanical properties, corrosion resistance properties, weld ability. 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. An introduction to their metallurgy and corrosion resistance roger a.
In this webinar youll learn about the metallurgical differences between commonly used stainless steels and factors that influence stainless steel strength and corrosion resistance. In the present work the manufacture of this type of steel from prealloyed and mixed powders is studied together with the possibility of obtaining duplex compositions of other than 50% ferrite50% austenite. Sintered duplex stainless steel seems to be very promising in. They are the austenitic, ferritic, and duplex austeniticferritic families. Adding 8% nickel to a ferritic chromium stainless steel makes an austenitic chromiumnickel stainless steel, for example type 304 stainless steel. With stainless steels it is common usage to employ this term for austeniticferritic steels with a high delta ferrite content in the range of 3060%. Austenitic stainless steels have many advantages from a metallurgical point of view. They are being offered by all the major stainless steel mills for a number of reasons. There is a lot of marketing activity surrounding these grades. Super duplex is an austeniticferritic iron chromium nickel alloy with molybdenum addition. Sandvik duplex stainless steels sandvik materials technology. Metallurgy of duplex stainless steels university of indonesia department of metallurgy and materials engineering ui group of duplex stainless steel 1.
Stainless steels are most notable for their corrosion resistance, which increases with increasing chromium content. Phases, invariant reactions, equilibrium phase diagrams and. Effects of low temperature aging on the mechanical properties and. To date little work has been done on powder metallurgical duplex austeniticferritic stainless steels. 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. High performance stainless steels nickel institute. Properties of duplex stainless steels made by powder metallurgy article pdf available in archives of materials science and engineering 284 april 2007 with 1,219 reads how we measure reads. Fecrni mon the microstructure of duplex stainless steels consists of a mixture of austenite and ferrite. Pdf properties of duplex stainless steels made by powder. Today, modern duplex stainless steel can be divided into four groups. Duplex stainless steels are about twice as strong as regular austenitic or ferritic stainless steels. The authors emphasize fundamental metallurgical principles governing microstructure evolution and property development of. Effect of composition profiles on metallurgy and corrosion behavior of duplex stainless steel weld metals diluting the nitrogen content of the austenite with increased nickel appears to degrade the weld pitting corrosion property by t.
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