The development history of duplex stainless steel

Reposted from http://bbs.bylm.net/read.php?tid=148365 A brief history of the development of duplex stainless steel. The development of duplex stainless steel began in the 1930s, with France obtaining the first patent in 1935. Three generations of duplex stainless steels have been developed. The first generation is represented by 329 steel, developed in the United States in the 1940s; it contains high levels of chromium and molybdenum, offering good resistance to local corrosion, but it has a relatively high carbon content (≤0.1%C). Subsequently, the former Soviet Union, Germany, the United States, and Japan successively carried out research and development. Since the 1970s, with the emergence and widespread use of refining technologies as well as the development of continuous casting technology. The second generation of 18Cr, 22Cr, and 25Cr duplex stainless steels was developed, most of which belong to the ultra-low C category. It also contains elements such as Mo, Cu, and Si, which improves its corrosion resistance. The super duplex stainless steels developed in the late 1980s belong to the third generation. These steels are characterized by a carbon content of only 0.01%-0.02%, a molybdenum content of up to about 4%, and a nitrogen content of up to 0.3%. The ferrite content in these steels ranges from 40% to 45%, and they possess excellent pitting resistance; their pitting resistance equivalent value (PRE=Cr% + 3.3×Mo% + 16×N%) is greater than 40. In China, the development of duplex stainless steels began in the mid-1970s; the Beijing Research Institute of Iron and Steel and the 52nd Research Institute developed 00Cr18Ni5Mo3Si2 and the new rare-earth duplex stainless steel SG52, respectively. Over the past decade, the development and application of duplex stainless steels have seen rapid progress, with new steel grades continuously being developed. Below are several newly developed duplex stainless steels. ①SAF2507 is a highly alloyed duplex stainless steel resistant to organic acid corrosion, developed by the Swiss company Sandvik. Its basic composition is 25Cr-7Ni-4Mo-0.30N; it exhibits excellent corrosion resistance as well as high mechanical properties, with a minimum yield strength of 550 MPa and tensile strength ranging from 800 to 1000 MPa. ②YUS DX1 is a high-strength, highly corrosion-resistant duplex stainless steel developed by Nippon Steel. It exhibits improved resistance to pitting and crevice corrosion. Its yield strength at room temperature is twice that of SUS 304 and SUS 316 steels, and it has greater resistance to stress corrosion compared to SUS 304 steel; its weldability is comparable to that of common austenitic stainless steels. ③NAS65 is a superplastic duplex stainless steel developed by the Japanese Metallurgical Industry; it exhibits good superplastic formability at low temperatures, has low flow stress, and superior corrosion resistance compared to SUS 304. Its corrosion resistance and mechanical properties remain unchanged after superplastic forming. ④UGIMA320 is a free-cutting duplex stainless steel developed by the British company Ugine-Savoie, featuring high strength, corrosion resistance, and machinability. It is particularly suitable for components used in chemical plants and paper mills in harsh corrosive environments such as those exposed to acids and chlorides. ⑤ A duplex stainless steel disclosed in a Korean patent, which possesses excellent thermoplasticity, resistance to high-temperature oxidation, corrosion resistance, and impact toughness. Its main components are: Cr 22%-27%, Ni 5.0%-8.0%, Mo 2.0%-5.0%, W 2.0%-5.0%, Cu less than 2.0%, and Ni 0.13%-0.30%; it is suitable for use in marine installations. At present, the annual global production of duplex stainless steel is not high (approximately 1% of the total stainless steel production). Since 1990, the annual growth rate of duplex stainless steel has been close to 17%, with annual production increasing from 24,000 tons in 1990 to 110,000 tons in 2002. Its product distribution is as follows: hot-rolled sheets account for 72%, cold-rolled sheets account for 14%, seamless pipes account for 8%, and others account for 6%. Research and development of duplex stainless steel are very active abroad, and it is already quite mature in terms of production, processing, and application. The adoption of duplex stainless steel in our country has progressed very rapidly; in 1999, the domestic consumption of such steel was around 2,000 tons, while by 2002 it had risen to 4,000 tons, with most of it being imported. Refining and chemical companies such as those in Nanjing, Zhenhai, Tianjin, and Jinan use duplex steel for components such as the linings of atmospheric and vacuum distillation towers, internal tower components, air coolers, and water coolers ； In some domestic methanol synthesis reactors, the catalyst tubes, as well as the heat exchange equipment used in urea production and the pump bodies of ammonium methoxide pumps, are all made of duplex steel ； In terms of transportation, Qingshan Shipyard of China Yangtze River Shipping Group adopted European construction standards and used imported double-phase steel plates to successfully build its first 18,500-ton chemical tanker, which has been exported to Belgium. The gathering pipeline in the Tarim Basin for the West-to-East Gas Transmission Project also plans to use double-phase stainless steel welded pipes, with an initial estimated consumption of around 3,000 tons. At present, Taiyuan Iron and Steel Group and Baosteel in China have developed five types of duplex stainless steels. Only the 3RE60 steel has been included in national standards and is produced on a large scale; the others are manufactured according to factory standards in limited quantities. In terms of application, there are still issues such as insufficient understanding of the properties of duplex steels by design and usage teams, as well as a need to improve the stability of product quality.

Thank you so much! :The handshake material is really good!

Great post, thanks. But 2507 is very inconvenient to use. The welding requirements are very high; it is difficult to weld, and repairs cannot be made once problems occur, as such repairs would result in the material being discarded. Thus, ZERON-100 was developed later; this material is primarily designed to address the welding issues associated with 2507, but it can be used in even more demanding environments than Hoke.

As nickel prices fluctuated and rose, stainless steel manufacturers later developed duplex steels with lower nickel content. For example, Otokumpu’s 2304 is used as a substitute for 304; it has a lower price and better corrosion resistance than 304. American Metal Technologies’ AL2003 is intended to replace 317L/316L – it is a material with high strength (comparable to 2205) and high corrosion resistance (second only to 2205), with a price similar to that of 316L. The principle behind these materials is to add nitrogen to low-nickel stainless steel alloys. As is well known, nickel plays a role in stabilizing the austenitic structure in stainless steel, and nitrogen also has this function; therefore, factories use nitrogen injection to achieve a stable austenitic structure. The reason for development is the high amount of nitrogen filled, which requires good smelting technology.

Is Sweden still the leading country in terms of duplex stainless steel production?