Advantages and disadvantages of duplex stainless steel
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This post was last edited by A pot of fragrant tea on 2012-6-28 22:16. Compared with austenitic stainless steel, the advantages of duplex stainless steel are as follows: (1) Its yield strength is more than twice that of ordinary austenitic stainless steel, and it possesses sufficient plasticity and toughness for molding purposes. Using duplex stainless steel to manufacture the walls of storage tanks or pressure vessels reduces the wall thickness by 30-50% compared to conventional austenitic steels, which helps to lower costs. (2) It possesses excellent resistance to stress corrosion cracking; even the duplex stainless steels with the lowest alloy content have a higher resistance to stress corrosion cracking than austenitic stainless steels, especially in environments containing chloride ions. Stress corrosion is a prominent problem that is difficult to address in conventional austenitic stainless steels. (3) The corrosion resistance of 2205 duplex stainless steel, which is the most widely used in many media, is superior to that of conventional 316L austenitic stainless steel. Super duplex stainless steel possesses extremely high corrosion resistance; in some media such as acetic acid and formic acid, it can even replace highly alloyed austenitic stainless steels as well as corrosion-resistant alloys. (4) It possesses good resistance to localized corrosion; compared with austenitic stainless steels with similar alloy contents, it exhibits superior performance in terms of wear corrosion and fatigue corrosion resistance. (5) It has a lower linear expansion coefficient than austenitic stainless steels and is close to that of carbon steel, making it suitable for bonding with carbon steel; this holds significant engineering importance, such as in the production of composite sheets or linings. (6) Under both dynamic and static loading conditions, austenitic stainless steel possesses a higher energy absorption capacity; this gives biphasic stainless steel a clear advantage in enabling structural components to withstand sudden accidents such as collisions and explosions, making it practically useful. Compared to austenitic stainless steels, the disadvantages of duplex stainless steels are as follows: (1) Their versatility and range of applications are inferior to those of austenitic stainless steels; for example, their operating temperature must be kept below 250 degrees Celsius. (2) Its ductility and toughness are lower than those of austenitic stainless steels, and its cold and hot working capabilities as well as formability are inferior to those of austenitic stainless steels. (3) There is a medium-temperature brittleness region; it is necessary to strictly control the heat treatment and welding procedures in order to prevent the formation of harmful phases that could degrade performance. Compared to ferritic stainless steels, the advantages of duplex stainless steels are as follows: (1) Their overall mechanical properties are better than those of ferritic stainless steels, especially in terms of ductility and toughness; they are not as sensitive to brittleness as ferritic stainless steels. (2) Except for stress corrosion resistance, its other local corrosion resistances are superior to those of ferritic stainless steels. (3) Its cold working process properties and cold forming properties are far superior to those of ferritic stainless steels. (4) Its weldability is also far superior to that of ferritic stainless steels; generally, no preheating is required before welding, and no heat treatment is needed after welding. (5) Its application range is wider than that of ferritic stainless steels. Compared to ferritic stainless steels, the disadvantages of duplex stainless steels are as follows: they contain high levels of alloying elements, resulting in a relatively high price; generally, ferritic steels do not contain nickel.
Thank you to the original poster for sharing! Thank you for your hard work. . . When purchasing stainless steel, more attention should be paid to its shortcomings, so that preventive measures can be taken accordingly. . .
You are absolutely right; when selecting materials, more attention should be paid to their shortcomings. Let’s exchange ideas together and improve upon one another; thank you
This post was last edited by li*nji on 2015-12-7 at 12:28. It has less toughness than ferritic and austenitic stainless steels; inadequate heat treatment can lead to the formation of microcracks and brittle fracture. It is recommended to use it with caution in applications subject to stress. The so-called dual-phase steels available in China claim to ensure a certain material quality, but they do not guarantee a specific microstructural pattern – this is actually a form of deception. Dual-phase steel refers to a microstructure in which two phases are evenly distributed, and this is related to heat treatment rather than chemical composition. There have been many cases of cracks in the drum of bipolar steel centrifuges in China, including those imported. In some new centrifuges, the drum exploded during no-load testing at the manufacturer’s facility, resulting in deaths! ! ! ! !
Hehe, the problems with the centrifuge drums occurred in Xiangtan; the issues were mainly related to welding and heat treatment – the welding process wasn’t proper. After we helped that company fix those problems, no further issues arose.