Three Typical Alloys with Ni&Cr Additions

Literature Review

316 stainless steel

French scientist Leon Gillet had documented the constitution of stainless steel in 1904, and the mixture of alloy started improving since that time. In 1911 Philip Monnartz of Germany did and let out the detail work on the corrosion resistance. In 1924, titanium was added and the 321 stainless steel was created by W.H. Hatfield, and the 316 series was created in earlier years. Type 316 steel is an austenitic chromium-nickel stainless steel that contains between two and three percent molybdenum. The molybdenum content increases corrosion-resistance, improves resistance to pitting in chloride ion solutions, and increases strength at high temperatures. Type 316 grade stainless steel is particularly effective in acidic environments. This grade of steel is effective in protecting against corrosion caused by sulfuric, hydrochloric, acetic, formic, and tartaric acids, as well as acid sulfates and alkaline chlorides [2]. SAE 316 grade stainless steel is the second common austenitic stainless steel after 304. Its primary alloying constituents after iron, are chromium (between 16-18%), nickel (10-12%) and molybdenum (2-3%). The addition of molybdenum provides greater corrosion resistance than 304, with respect to localized corrosive attack by chlorides and to general corrosion by reducing acids, such as sulfuric acid 316L, grade is the low carbon version of 316 stainless steel [3].

Iconel690

INCONEL alloy 690 (UNS N06690/W. Nr. 2.4642) is a high-chromium nickel alloy having excellent resistance to many corrosive aqueous media and high temperature atmospheres. In addition to its corrosion resistance, alloy 690 has high strength, good metallurgical stability, and favorable fabrication characteristics. The chemical composition of INCONEL alloy 690 is listed in Table 1. The substantial chromium content gives the alloy outstanding resistance to oxidizing chemicals and to high-temperature oxidizing gases. The high level of nickel imparts resistance to stress corrosion cracking in chloride-containing environments as well as to sodium hydroxide solutions. The properties of INCONEL alloy 690 are useful for various applications involving nitric or nitric/hydrofluoric acid solutions. Examples are tail-gas reheaters used in nitric acid production and heating coils and tanks for nitric/hydrofluoric solutions used in pickling of stainless steels and reprocessing of nuclear fuels. The alloy’s resistance to sulfur-containing gases makes it an attractive material for such applications as coal-gasification units, burners and ducts for processing sulfuric acid, furnaces for petrochemical processing, recuperating instruments, incinerators, and glass vitrification equipment for radioactive waste disposal. In various types of high-temperature water, alloy 690 displays low corrosion rates and excellent resistance to stress-corrosion cracking. Thus, alloy 690 is widely used for steam generator tubes, baffles, tube sheets, and hardware in nuclear power generation. The Inconel family of alloys was first developed in the 1940s by research teams at Wiggin Alloys (Hereford, England), which has since been acquired by Special Metals Corporation [4], in support of the development of the Whittle jet engine [5]. In June 2018, SpaceX CEO Elon Musk announced completion of work on a new Inconel superalloy called SX 300 developed for high-temperature, high-pressure, highly-oxidative environments in a rocket engine [6]. INCONEL alloy 690 (UNS N06690/W. Nr. 2.4642) is a high-chromium nickel alloy having excellent resistance to many corrosive aqueous media and high temperature atmospheres. In addition to its corrosion resistance, alloy 690 has high strength, good metallurgical stability, and favorable fabrication characteristics. The chemical composition of INCONEL alloy 690 is listed in Table 1. The substantial chromium content gives the alloy outstanding resistance to oxidizing chemicals and to high-temperature oxidizing gases. The high level of nickel imparts resistance to stress corrosion cracking in chloride-containing environments as well as to sodium hydroxide solutions. The properties of INCONEL alloy 690 are useful for various applications involving nitric or nitric/hydrofluoric acid solutions. Examples are tail-gas reheaters used in nitric acid production and heating coils and tanks for nitric/hydrofluoric solutions used in pickling of stainless steels and reprocessing of nuclear fuels. The alloy’s resistance to sulfur-containing gases makes it an attractive material for such applications as coal-gasification units, burners and ducts for processing sulfuric acid, furnaces for petrochemical processing, recuperating instruments, incinerators, and glass vitrification equipment for radioactive waste disposal. In various types of high-temperature water, alloy 690 displays low corrosion rates and excellent resistance to stress-corrosion cracking. Thus, alloy 690 is widely used for steam generator tubes, baffles, tube sheets, and hardware in nuclear power generation.

Incoloy800

The Incoloy800 was invented by the Special Metals Corporation Group of Companies and then introduced to the market in the 1950s to fill the need for heat and corrosion-resistant alloy with a relatively low nickel content since nickel was, at the time, designated a “strategic” metal. In 1963, the alloy was approved by the ASME Boiler and Pressure Vessel Committee, and the design stresses were published in Code Case 1325. For the first time, aluminum and titanium were listed as purposeful additions (at 0.15 to 0.60% each), and annealed material was differentiated from solution-annealed material. Over the past forty years, it has been widely used for its strength at high temperatures and its ability to resist oxidation, carburization, and other types of high-temperature corrosion. Applications include furnace components and equipment, petrochemical furnace cracker tubes, pigtails and headers, and sheathing for electrical heating elements [7].