Corrosion resistant "Three Musketeers" above Harrods alloy C276: VDM59, C-2000 and INCONEL 686
1. Development history of Harolds alloy The same is true of the materials industry. The C alloy, which began to be used in the 1930s, has been largely phased out except for certain casting materials. In the second half of the 20th century, corrosion-resistant alloys developed rapidly, such as alloys C-276 in the 1960s, C-4 in the 1970s, C-22 and 622 in the 1980s and 59,686, C-2000 and MAT21 in the 1990s. The improvement of corrosion resistance not only overcomes the limitation of alloy C, but also expands the application of materials with more stringent requirements in chemical industry. More and more working conditions and media are simultaneously antioxidant and reductive, in low pH, high chloride, oxidizing environment has a good resistance to point corrosion and gap corrosion, and can completely avoid stress corrosion rupture, where to go the development and application of materials? Special steel 100 seconds. The high-grade corrosion-resistant nickel-base alloys of several major nickel alloy manufacturers abroad have been found in small compilation. The comprehensive corrosion-resistant properties are above the alloy C-276. The main ingredients of the material are compared by the reader himself:
German VDM first invented 59 alloy In the late 1980s, Germany Thyssen Krupp VDM began research and development of alloy 59, officially released in 1990, is the world's first and high corrosion resistance of the new generation of nickel-based alloys. It overcomes the disadvantages of alloy C-22 and alloy C-276, the carbon content of silicon is very low, it is not easy to produce grain boundary precipitation in the process of hot forming or welding, and the thermal stability is very good. The alloy has excellent corrosion resistance and good corrosion resistance to mineral acids such as nitric acid, phosphoric acid, sulfuric acid and hydrochloric acid, especially for mixed acids of sulfuric acid and hydrochloric acid, and is resistant to the corrosion of the full concentration of hydrochloric acid below 40°C. not sensitive to stress corrosion cracking caused by chloride ions. alloy 59 is one of the most nickel-containing alloys in the c alloy family, and has the highest chromium, molybdenum, iron content is the least, usually less than 1%, without adding any other elements such as tungsten, copper, titanium or tantalum, is the most "pure" ni-cr-mo alloy. The purity and balance of this ternary Ni-Cr-Mo system in the 59 alloy is also the main reason for the excellent thermal stability of the alloy.
3. Inconel 686 alloy from SMC, USA Inconel 686, a patented product invented in 1993 by Special Metals of the United States, is a Ni-Cr-Mo-W alloy with a high degree of alloying and a single austenite structure. 686 is very similar to the C-276 alloy composition, the chromium content increases from 16% to 21% while the molybdenum and tungsten contents remain at similar levels. 686 alloy is an overalloyed material containing a total of 41% chromium, molybdenum and tungsten. Inconel 686 is suitable for use in corrosive environments with high concentrations of chloride ions in amphoteric acid or amphoteric mixed acid, especially amphoteric mixed acid. with excellent resistance to uniform corrosion, electrochemical corrosion, local erosion and hydrogen embrittlement in seawater, the effect of seawater on its fatigue strength is also minimal. therefore, the inconel686 alloy is ideal for marine environmental application materials such as fasteners in seawater. the yield strength after cold processing strengthening can be up to 150 ksi (1000 mpa) with the same corrosion resistance as the solid solution state. Inconel686 alloys are used in corrosive environments such as chemical processes, pollution control (flue gas desulfurization), papermaking, pharmaceuticals and waste disposal. The welding material of Inconel686 is ideal for surfacing corrosion resistant material of steel surface.
Hastelloy C-2000 Hasteley C-2000 is a 1995 patented product from Haynes. Ni-Cr-Mo alloy is a high-Cr anti-oxidation medium, high-Mo and W anti-reducing medium. However, because of the limitations of metallurgy, it is impossible to improve the antioxidant and reductive properties by increasing the content of Cr, Mo and W. Hasteley C-2000 is designed to solve this difficult problem, and its biggest difference from other Ni-Cr-Mo alloys is the innovative addition of 1.6% Cu, which greatly improves the ability of the alloy to resist the corrosion of reducing medium. However, the addition of copper leads to a decrease in local corrosion resistance, and the thermal stability is also inferior to that of alloy 59. The resistance of the alloy to pitting and gap corrosion is better than that of C-276, and the forming, welding, machining characteristics are similar to that of C-276. "Special Steel 100 Seconds" wrote a separate early article," Double-sided king: oxidation and reduction resistance to the alloy C-2000 corrosion," interested readers can read it on their own. 5. Summary Inconel 686 alloy from Special Metals in the United States and Nicro-fer5923hMo (Alloy59) from VDM in Germany belong to the same nickel-chromium-molybdenum alloy. The two alloys, combined with Hastelloy C-2000 by Haynes of the United States, are known as the world's top three nickel-based alloys, representing the highest achievement of the world's metallurgical industry and a new generation of alloys. For some corrosion resistant conditions, if the alloy C276 cannot be applied, you might as well try the above three grades. More specific salt-tolerant acid, sulfuric acid, hydrofluoric acid, hydrobromide, nitric acid, phosphoric acid and other operating conditions data, more pictures, too lazy to post ah, please readers "special steel 100 seconds" background message backup.
