Austenitic stainless steels are classified in the 200 and 300 series, with 16% to 30% chromium and 2% to 20% nickel for enhanced surface quality, formability, increased corrosion and wear resistance. Lean duplex stainless steel 2101 uns s32101 possesses high strength coupled with corrosion resistance comparable to austenitic grades like 316l. Grades stainless steel duplex grade astm a815 s31803, 2205, en 1. Sandvik duplex stainless steels sandvik materials technology. Duplex 2205 is a twophase, ferritic, austenitic 22% chromium, 3% molybdenum, 5 to 6% nickel alloyed stainless steel. Stainless steel world october 2015 3 alloying lean duplex grades present lower pitting corrosion resistance than the 304 austenitic grades. Duplex stainless steels are about twice as strong as regular austenitic or ferritic stainless steels. Ferritic stainless steels means 400 series contain 10% to 30% chromium content martensitic stainless steels. In view of the continuous improvement of their properties and their growing availability, duplex stainless steels will remain an attractive solution to the future needs of designers and users in mechanical engineering. Duplex stainless steel plate contains relatively high levels of chromium between 18% and 28% and low to moderate amounts of nickel between 1. Product bulletin high alloy stainless steels september. Figure 1 provides a useful summary of some of the compositional and property linkages in the stainless steel family.
The society of automotive engineers sae designates sae steel grades. Elongation, toughness and work hardening rates are lower than austenitic grades, but higher than those of ferritic grades. Stainless steel grade chart atlas steels specialty steels product reference manual section 9. Austenitic stainless steels are nonhardenable by heat treating. Family of grades lean standard super hyper 329 one of the oldest grades 3re60, alloy 86 for suction rolls duplex stainless steel improved corrosion and more importantly, stress corrosion cracking resistance higher strength and hardness. S32750 grade s32750 is a super duplex stainless steel containing 25% chromium, 7% nickel and 4% molybdenum.
Duplex s tainless steel are also magnetic, a property. Stainless steel in metallurgy, stainless steel, also known as inox steel or inox from french inoxydable, is defined as a steel alloy with a minimum of 10. Thanks to its unique properties such as durability, lowmaintenance and resistance to corrosion, stainless steel is not only the strongest, but also the most economically sustainable choice. 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.
Duplex stainless steels have a twophase microstructure of austenite and ferrite grains. Pdf duplex stainless steelsan overview researchgate. Pdf this paper presents an overview of duplex stainless steels dss with. The newest fast growing family of stainless steels is duplex alloys. Duplex stainless steel is a type of stainless steel that is composed of grains of two types of stainless steel material, austenitic and ferritic. Duplex stainless steels 1 developments, grades and specifications 1. Its popularity also means there are seemingly a million different types of stainless steel grades. The word duplex refers to the twophase microstructure of ferritic and austenitic steel grains. When considering duplex stainless steel for heat exchangers, often there is even more benefit. Unlike carbon steels, forta range duplex products with their superior corrosion. Issf duplex stainless steels international stainless steel. S31803 is commonly called 2205 and is the most widely used duplex stainless steel. Practical guidelines for the fabrication of duplex stainless steels. Appendices printed november 2000 1 s9 chemical analysis % speci.
As a general rule, stainless deserves consideration if your engineering project requires at least one of these qualities. S31803, cd3mn duplex s31803 contains approximately 22% chromium, 5% nickel, and 3% molybdenum. Types of stainless steel duplex and super duplex grades. The second main conclusion is that mn additions appear to be detrimental for corrosion. Duplex stainless steels are graded for their corrosion performance depending on their alloy content.
Stainless steel is the term used to describe an extremely versatile family of. J2101 uns s32101 en 1 indias largest stainless steel. To compete with the 316 grades only 2202 and 2304 dss should be considered. While soft and ductile in the solution annealed condition, it is capable of high properties with a single precipitation or aging.
Duplex stainless steel grades have a range of corrosion resistance, similar to the range for austenitic stainless steels. High strength martensitic and precipitation hardening grades. The a790 specification covers seamless duplex and super duplex pipes uns s3220531803 and uns s3275032760 special ss grade with a mixed ferritic. Duplex grades match austenitic grades in corrosion resistance and have higher strength in the annealed condition but present the designer with challenges with regard to embrittling phases that can form with prolonged exposure to elevated temperatures and only moderate ductility like the ferritic alloys. The duplex structure gives this family of stainless steels a combination of attractive properties. 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. This page has links to various data sheets of jindal stainless ltd. What the differences and advantages are, will be explained in the following. Duplex stainless steels offer several advantages over the common austenitic stainless steels.
Lambert, in sustainability of construction materials, 2009. The firstgeneration duplex grades and the most common austenitic stain less steels are included for comparison. Production of stainless steels with specific restrictions in certain types, the stainless steels can be shaped and fabricated in conventional ways. These are four digit numbers which represent chemical composition standards for steel specifications.
They are being offered by all the major stainless steel mills for a number of reasons. Sandvik saf 2304 is a lean duplex stainless steel containing no molybdenum and a low nickel content. Super duplex falls under the duplex stainless steel grouping. Duplex stainless steel grades are covered by major standards, such as en, iso.
These steels have approximately two times the yield strength of austenitic grades and require greater loads during cold forming. There is a lot of marketing activity surrounding these grades. The table shows nominal chemical compositions of the hyper duplex stainless steel grades uns s32707 sandvik saf 2707 hd and uns s33207 sandvik saf 3207 hd as well as super duplex stainless steel grade uns s32750 sandvik saf 2507. Pren is useful for comparing and ranking the grades of duplex stainless steels, but it can rarely be useful as a prediction for a suitable.
It is a high strength, low cost alternative to standard austenitic grades such as astm 304l and 316l. The high corrosion resistance and excellent mechanical properties of duplex stainless steels can be attributed to their chemical composition and. Atlas steels metal distribution stainless steel grade chart atlas steels specialty steels product reference manual section 9. Today, modern duplex stainless steel can be divided into four groups.
The ferritic austenitic grades have a ferrite matrix intermix with austenite and in other words. Duplex stainless steels have structures that combine aspects of ferritic and austenitic or martensitic grades. Stainless steels duplex stainless steels properties. Most common grades which accounts for 70% of all stainless steel. The resultant alloys are designed to display a favourable combination of the parent grades. There is a conference on the subject of duplex every 23 years where dozens of highly technical papers are presented. Practical guidelines for the fabrication of duplex. Duplex stainless steels table 5 have an annealed structure which is typically about equal parts of austenite and ferrite. 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. Alloy 32750 is a super duplex stainless steel supplied in the hot worked and solution annealed condition. The following data sheets can be used as a reference to have better understanding about different stainless steel grades. The higher chromium, molybdenum and nitrogen contents result in a pitting resistance equivalent number pren of 40.
Duplex austenitic ferritic duplex stainless steels were born and have been actively developed by european companies since 1935. Duplex stainless steels have significantly better toughness and ductility than ferritic grades. Duplex grades penn stainless stainless steel plate. Stainless steel is the universal name for a number of different steels used primarily for their anticorrosive element. The duplex grades are not heat treatable and have a low response to cold work,so are used in the annealed condition. 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. The firstgeneration duplex grades and the common austenitic stainless steels are included for comparison. The designation duplex comes from the biphasic structural constitution of a ferritic and an austenitic phase, both to almost. Sandvik saf 3207 hd contains the highest amounts of the alloying elements. Stainless steel properties, grades and price per kg. Duplex stainless steel is a popular material in many industries.
It has been written primarily from a european perspective and may not fully reflect the practice in other regions. 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. Many duplex stainless steel grades are offered today, partly as a result of patents, partly because new grades are needed to meet new requirements, particularly for use in the oil and gas industry. Lean duplex such as 2304, which contains no deliberate mo addition. The relatively new austeniticferritic duplex stainless steel grades will be compared to the standard austenitic grades 1. Duplex and highstrength stainless steels outokumpu is the global. Although there is a fairly long list of uns grades, only a few of them make the largest part. They are easy to weld and fabricate, although not as easy as the austenitic grades. It is well established that nitrogen, in combination with molybdenum, greatly improves resistance to pitting corrosion.
A list of duplex grades is provided in appendix 2 and the correspondence between standards is given in appendix 3. Introduction to stainless steels asm international. One of the most widely used precipitation hardening grades in the business. Type 2205the most widely used duplex ferriticaustenitic stainless steel grade. The lower nickel content of the duplex grades means a better thermal conductivity as. Duplex stainless steels are extremely corrosion resistant, work hardenable alloys. Magnetic response austenitic grades have low magnetic permeability.
The stainless steel family a short description of the various grades of stainless steel and how they fit into distinct metallurgical families. The ferritic and austenitic stainless steel grades have approximately equal proportions i. Duplex stainless steels can be cold formed and expanded using a variety of forming operations. Duplex stainless steel an overview sciencedirect topics. The astm a312 specification covers seamless and welded austenitic stainless steel pipes used for high temperature andor corrosive service the most common grades are 304304l and 316316l. Pdf duplex stainless steels microstructure properties and. 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. Stainless steel grades chart pdf types of stainless steel. Duplex stainless steels have roughly twice the yield strength of their counterpart austenitic grades. The typical chemical compositions of outokumpu grades.
Super duplex stainless steels article pdf available in materials science and technology 88. No other stainless steels are suitable at very low temperatures. Sandvik saf 2707 hd, saf 2507, saf 2205, saf 2304 and sanicro are. Although not formally defined, it is generally accepted that the lesser phase will be at least 30% by volume. As a super duplex stainless steel, it combines the desirable aspects of both austenitic and ferritic grades. Duplex stainless steel, lean duplex and super duplex. Stainless steel is an ideal material to create lasting solutions in demanding applications. However, there are different grades with different chemical compositions.
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