Nickel Alloy Materials Engineering Experts

Nickel Alloys are used extensively in many industries. There are many types of nickel alloys, all design for specific applications and more often than not they are not used correctly. Below is a partially list of the more commonly used nickel alloys and a brief description to help you appreciate how complicated their correct usage can be.

13.5 NICKEL (ALL )

13.5.1 NICKEL ALLOY

13.5.1.1 NICKEL 200

Nickel 200 and Nickel 201 are solid solution strengthened, commercially pure wrought materials. Typically, the elemental restrictions of both alloys are combined into one, dual-certified chemistry resulting in a single alloy with the desired characteristics of both alloys. Applications where Nickel 200/201 can be used include chemical processing and storage, synthetic fiber production, and processes where sodium hydroxide and fluorine is used. Other applications include aerospace and defense as well as food processing. Nickel 200/201 has exceptional resistance to caustic alkalies at various temperatures and concentrations. When operating temperatures are expected to exceed 600°F, carbon content becomes critical. The lower carbon content of Nickel 201 makes the material resistant to graphitization and therefore less subject to embrittlement. Pressure vessels and vessel components can be constructed from Nickel 201 according to the ASME Boiler and Pressure Vessel Code, Section VIII, Division 1 for use up to 1250°F. Resistance to Corrosion Both Nickel 200 and 201 offer corrosion resistance in reducing and neutral media as well as in oxidizing atmospheres provided that the oxidizing media allows the formation of a passive oxide film. This oxide film accounts for the materials excellent resistance in caustic environments.

13.5.1.2 NICKEL 201

Nickel 201 Alloy is similar to Nickel 200 Alloy and is a low carbon modification of the 200 Alloy. It has a low annealed hardness and very low work-hardening rate. Those who use Nickel 201 Alloy find it desirable in deep drawing, spinning, and coining. It addition, it can be applied to corrosion-resistant equipment including but not limited to: caustic evaporators, spun anodes, and laboratory crucibles.

13.5.1.3 NICKEL 205

Nickel 205 Alloy contains controlled additions of magnesium and titanium (small amounts of both) and exhibits good oxidation resistance. It’s commonly used in support wires, vacuum tube components, pins, terminals, lead wires, and other electronic components of the like.

13.5.1.4 NICKEL 270

Nickel 270 Alloy is a high purity nickel alloy commonly used for electrical resistant thermometers

13.5.2 HASTALLOY

13.5.2.1 HASTALLOY ALLOY C276 ALTERNATIVE HASTALLOY C Other common names: Alloy C276, Hastelloy C, Inconel® C-276

C276 is a nickel-molybdenum-chromium superalloy with an addition of tungsten designed to have excellent corrosion resistance in a wide range of severe environments. The high nickel and molybdenum contents make the nickel steel alloy especially resistant to pitting and crevice corrosion in reducing environments while chromium conveys resistance to oxidizing media. The low carbon content minimizes carbide precipitation during welding to maintain corrosion resistance in as-welded structures. This nickel alloy is resistant to the formation of grain boundary precipitates in the weld heat-affected zone, thus making it suitable for most chemical process application in an as welded condition. Although there are several variations of the Hastelloy nickel alloy, Hastelloy C-276 is by far the most widely used. Alloy C-276 is widely used in the most severe environments such as chemical processing, pollution control, pulp and paper production, industrial and municipal waste treatment, and recovery of sour natural gas

13.5.2.2 ALLOY B-2 ALTERNATIVE HASTALLOY B-2 UNS Number N010665 Other common names: Alloy B-2

B2 is a solid solution strengthened, nickel-molybdenum alloy, with significant resistance to reducing environments like hydrogen chloride gas, and sulfuric, acetic and phosphoric acids. Molybdenum is the primary alloying element which provides significant corrosion resistance to reducing environments. This nickel steel alloy can be used in the as-welded condition because it resists the formation of grain-boundary carbide precipitates in the weld heat-affected zone. This nickel alloy provides excellent resistance to hydrochloric acid at all concentrations and temperatures. In additions, Hastelloy B2 has excellent resistance to pitting, stress corrosion cracking and to knife-line and heat-affected zone attack. Alloy B2 provides resistance to pure sulfuric acid and a number of non-oxidizing acids. Limiting Factors of Hastelloy B2 Alloy B-2 has poor corrosion resistance to oxidizing environments, therefore, it is not recommended for use in oxidizing media or in the presence of ferric or cupric salts because they may cause rapid premature corrosion failure. These salts may develop when hydrochloric acid comes in contact with iron and copper. Therefore, if this alloy is used in conjunction with iron or copper piping in a system containing hydrochloric acid, the presence of these salts could cause the alloy to fail prematurely. In addition, this nickel steel alloy should not be used at temperatures between 1000° F and 1600° F because of a reduction in the ductility in the alloy.

13.5.2.2 ALLOY B-3 ALTERNATIVE HASTALLOY B-3 UNS Number N010675

B-3 is a nickel-molybdenum alloy with excellent resistance to pitting, corrosion, and stress-corrosion cracking plus, thermal stability superior to that of alloy B-2. In addition, this nickel steel alloy has great resistance to knife-line and heat–affected zone attack. Alloy B-3 also withstands sulfuric, acetic, formic and phosphoric acids, and other non-oxidizing media. Furthermore, this nickel alloy has excellent resistance to hydrochloric acid at all concentrations and temperatures. Hastelloy B-3’s distinguishing feature is its ability to maintain excellent ductility during transient exposures to intermediate temperatures. Such exposures are routinely experienced during heat treatments associated with fabrication. Limiting Factors of Hastelloy B-3 Alloy B-3 has poor corrosion resistance to oxidizing environments, therefore, it is not recommended for use in oxidizing media or in the presence of ferric or cupric salts because they may cause rapid premature corrosion failure. These salts may develop when hydrochloric acid comes in contact with iron and copper. Therefore, if this nickel steel alloy is used in conjunction with iron or copper piping in a system containing hydrochloric acid, the presence of these salts could cause the alloy to fail prematurely.

13.5.2.3 ALLOY C-22 ALTERNATIVE HASTALLOY C-22 UNS Number N06022 Other common names: Alloy C22

C22, also known as alloy C22, is a versatile austenitic nickel-chromium-molybdenum-tungsten alloy with enhanced resistance to pitting, crevice corrosion and stress corrosion cracking. The high chromium content provides good resistance to oxidizing media while the molybdenum and tungsten content give good resistance to reducing media. This nickel steel alloy also has excellent resistance to oxidizing aqueous media including wet chlorine and mixtures containing nitric acid or oxidizing acids with chlorine ions. Other corrosives Hastelloy C-22 has resistance to are oxidizing acid chlorides, wet chlorine, formic and acetic acids, ferric and cupric chlorides, sea water, brine and many mixed or contaminated chemical solutions, both organic and inorganic. This nickel alloy also offers optimum resistance to environments where reducing and oxidizing conditions are encountered in process streams. This is beneficial in multi- purpose plants where such “upset” conditions occur frequently. This nickel alloy resists the formation of grain-boundary precipitates in the weld heat-affected zone, thus making it suitable for most chemical process applications in the as-welded condition. Alloy C-22 should not be used in service temperatures above 1250° F due to the formation of detrimental phases which form above this temperature.

13.9.2.4 ALLOY X ALTERNATIVE HASTALLOY X AND INCONEL HX ASTM B435, B366, B572, B619 B622, B626, B751, B775, B829 UNS Number N06002 DIN 2.4665 Other common names: Alloy X, Inconel® HX

X is a nickel-chromium-iron-molybdenum superalloy with outstanding high temperature strength, oxidation resistance, and fabricability. Alloy X’s oxidation resistance is excellent up to 2200° F. This nickel steel alloy has also been found to be exceptionally resistant to stress-corrosion cracking in petrochemical applications. Matrix stiffening provided by the molybdenum content results in high strength in a solid-solution alloy having good fabrication characteristics. Although this nickel alloy is primarily noted for heat and oxidation resistance it also has good resistance to chloride stress-corrosion cracking, carburization, and excellent resistance to reducing or carburizing atmospheres. Two common conditions that often lead to early failure in high temperature alloys, carburization and nitriding, Hastelloy X resists. In what applications is Hastelloy X used? • Gas turbines • Petrochemical industry • Industrial furnaces • Heat treating equipment • Nuclear engineering • Jet engine combustion chambers • Aircraft cabin heaters • Turbine exhaust components Alloy X is one of the most widely used nickel base superalloys for gas turbine engine combustion zone components such as transition ducts, combustor cans, spray bars and flame holders as well as in afterburners, tailpipes and cabin heaters. It is recommended for use in industrial furnace applications because it has unusual resistance to oxidizing, reducing and neutral atmospheres. Hastelloy X is also used in the chemical process industry for retorts, muffles, catalysts support grids, furnace baffles, tubing for pyrolysis operations and flash drier components.

13.5.3 INCOLOY (NICKEL BASED ALLOY)

The registered trademark name, Incoloy, is applied as the prefix name to several highly corrosion resistant high temperature strength metal alloys produced by Special Metals Corporation. These Incoloy alloys or superalloys are nickel-based alloys that exhibit traits that include good corrosion resistance in aqueous environments, excellent strength and oxidation resistance in high-temperature settings, good creep-rupture strength, and ease of fabrication. Alloys of identical chemical and mechanical properties are available from other manufacturers and offer excellent alternatives to the various Incoloy brand alloys. The corrosion-resistant superalloys are widely used in extreme environments where tremendous heat and corrosion resistance is paramount to the integrity of the end product. Chemical and petrochemical processing, power plants, and oil and gas industries widely use these superalloys.

13.5.3.1 ALLOY 20 ALTERNATIVE CARPENTER 20 / INCOLOY 20 UNS N08020 ASTM A 265, B 366, B 463, B 464, B 471, B 472, B 473,B 474, B 475 – NACE MR0175 Other common names: Carpenter 20, 20Cb-3®, Incoloy® alloy 20

Alloy 20, also known as Carpenter 20, is a nickel-iron-chromium austenitic alloy that was developed for maximum resistance to acid attack, specifically sulfuric acid. This superalloy has excellent resistance to general corrosion, pitting, and crevice corrosion in chemicals containing chlorides and sulfuric, phosphoric, and nitric acids. It also contains niobium for stabilization against sensitization and resultant intergranular corrosion. Carpenter 20 combines excellent corrosion resistance with elevated mechanical properties and relatively easy fabrication. Although originally designed for use in sulfuric acid related industries, Alloy 20 is now a popular choice for a wide variety of industries including the chemical, food, pharmaceutical, and plastics industries. In addition, this superalloy is used in heat exchangers, mixing tanks, metal cleaning and pickling equipment, and piping. There has long been a debate on whether Carpenter 20 is a stainless steel or a nickel alloy because the nickel content is right on the border of defining it as one way or the other. So, depending on who you talk to this alloy may be referred to as alloy 20 Stainless Steel or as a nickel alloy. Either way it is still great for corrosion resistance. What are the characteristics of Alloy 20? • Excellent general corrosion resistance to sulfuric acid • Excellent resistance to chloride stress corrosion cracking • Excellent mechanical properties and fabricability • Minimal carbide precipitation during welding • Excels in resisting corrosion to hot sulfuric acids In what applications is Alloy 20 used? • Synthetic rubber manufacturing equipment • Processing of pharmaceuticals, plastics and organic and heavy chemicals • Tanks, piping, heat exchangers, pumps, valves, and other process equipment • Acid cleaning and pickling equipment • Chemical process piping, reactor vessels • Bubble caps • Petrochemical process equipment • Food and dye production

13.5.3.2 ALLOY 800 ALTERNATIVE TO INCOLOY 800 – (NI-FE-CR)

800, 800H, and 800HT are nickel-iron-chromium alloys with good strength and excellent resistance to oxidation and carburization in high-temperature exposure. These nickel steel alloys are identical except for the higher level of carbon in alloy 800H, and the addition of up to 1.20 percent aluminum and titanium in alloy 800HT. Incoloy 800 was the first of these alloys and it was slightly modified into Incoloy 800H. This modification was to control carbon (.05-.10%) and grain size to optimize stress rupture properties. Incoloy 800HT has further modifications to the combined titanium and aluminum levels (.85-1.20%) to ensure optimum high temperature properties. The nickel alloy is dual certified (800H/HT) and combines the properties of both forms. Incoloy 800H/HT alloy was intended for high temperature structural applications. The nickel content makes the alloys highly resistant to both chloride stress-corrosion cracking and to embrittlement from precipitation of sigma phase. The general corrosion resistance is excellent. In the solution annealed condition, alloys 800H and 800HT have superior creep and stress rupture properties. Today, most suppliers, only carry the dual certified 800H/HT alloy.

800 is primarily used in applications with temperatures up to 1100° F, where alloys 800H and 800HT are normally used in temperatures above 1100° F where resistance to creep and rupture is required. The chemical balance allows the nickel steel alloy to exhibit excellent resistance to carburization, oxidation and nitriding atmospheres. Incoloy 800HT will not become embrittled even after long periods of usage in the 1200-1600° F range where many stainless steels become brittle. Excellent cold forming characteristics typically associated with the nickel-chromium alloys are exhibited with 800HT. When cold formed extensively the grain size produces a visibly undulated surface called “orange peel”. Incoloy 800HT can be welded by the common techniques used on stainless steels. What are the characteristics of Incoloy 800H/HT? • High temperature strength • High creep rupture strength • Resistant to oxidation and carburization in high temperature environments • Good corrosion resistance in many acidic environments • Good resistance to many sulfur-containing atmospheres *Note that the chemical composition of Incoloy 800HT will always be within the limits of Incoloy 800H. *Note the limits of Incoloy 800H may or may not be within the limits of Incoloy 800HT. In what applications is Incoloy 800H/HT used? • Ethylene furnace quench boilers • Hydrocarbon cracking • Valves, fittings and other components exposed to corrosive attack from 1100-1800° F • Industrial furnaces • Heat-treating equipment • Chemical and petrochemical processing • Super-heater and re-heaters in power plants • Pressure vessels • Heat exchangers Alloys 800H/HT are used in a variety of applications involving exposure to corrosive environments and high temperatures such as heat treating equipment, chemical and petrochemical processing, nuclear power plants and the paper pulp industry. Heat-treating equipment such as baskets, trays, and fixtures employ Incoloy 800H/HT. Chemical and petrochemical processing industries use the alloys for heat exchangers and other piping systems in nitric acid media especially where resistance to chloride stress-corrosion cracking is required. Power plants use them for super-heater and re-heater tubing.

13.5.3.3 — 825 – (NI-FE-CR) W ADDITION OF MOLY AND CU UNS Number N08825 Other common names: Alloy 825

825 is a nickel-iron-chromium alloy with additions of molybdenum and copper. This nickel steel alloy’s chemical composition is designed to provide exceptional resistance to many corrosive environments. It is similar to alloy 800 but has improved resistance to aqueous corrosion. It has excellent resistance to both reducing and oxidizing acids, to stress-corrosion cracking, and to localized attack such as pitting and crevice corrosion. Alloy 825 is especially resistant to sulfuric and phosphoric acids. This nickel steel alloy is used for chemical processing, pollution-control equipment, oil and gas well piping, nuclear fuel reprocessing, acid production, and pickling equipment. What are the characteristics of Incoloy 825? • Excellent resistance to reducing and oxidizing acids • Good resistance to stress-corrosion cracking • Satisfactory resistance to localized attack like pitting and crevice corrosion • Very resistant to sulfuric and phosphoric acids • Good mechanical properties at both room and elevated temperatures up to approximately 1020° F • Permission for pressure-vessel use at wall temperatures up to 800°F Corrosion Resistance Alloy 825 has a high level of corrosion resistance. It resists general corrosion, pitting, crevice corrosion, intergranular corrosion, and stress-corrosion cracking in both reducing and oxidizing environments. In what applications is Incoloy 825 used? • Chemical Processing • Pollution-control • Oil and gas well piping • Nuclear fuel reprocessing • Components in Pickling equipment like heating coils, tanks, baskets and chains • Acid production Alloy 825 has good mechanical properties from cryogenic temperatures to moderately high temperatures. However, exposure to temperatures above 1000° F can result in microstructural changes that significantly lower ductility and impact strength. Alloy 825 should not be used at temperatures where creep-rupture properties are design factors.

13.5.4 MONEL

The registered trademark name, Monel, is applied as the prefix name to several corrosion resistant alloys produced by Special Metals Corporation. These alloys are nickel-based and exhibit traits that include high resistance to atmospheric corrosion, salt water, and various acid and alkaline solutions. Alloys of identical chemical and mechanical properties are available from other manufacturers and offer excellent alternatives to the various Monel® brand alloys. The corrosion-resistant alloy is widely used in the marine, oil and chemical processing industries. Monel Availability Monel 400, K-500 & R-405are available in the form of plate, sheet, pipe, tubing, fittings, bar, wire and rod. What are the Characteristics of Monel? • Good resistance to acids such as hydrofluoric and sulfuric acid • Highly resistant to alkalis • Malleable • Highly corrosion resistant • Stronger than steel In what Applications are Monel alloys used? • Pump shafts, oil-well tools, instruments, doctor blades and scrapers, springs, valve trim, fasteners, marine propeller shafts • Marine components • Chemical and hydrocarbon processing equipment • Valves, pumps, shafts, fittings, heat exchangers Monel Trivia Monel was discovered by Robert Crooks Stanley who worked for the International Nickel Company in 1901. The new alloy was named in honor of the president of the company, Ambrose Monell. *Monel® is a registered trademark of Special Metals Corporation group of Companies.

13.5.4.1 ALLOY 400 ALTERNATIVE MONEL 400 (67% NI – 23 % CU) UNS N04400 Other common names: Alloy 400

400 is a nickel-copper alloy (about 67% Ni – 23% Cu) that is resistant to sea water and steam at high temperatures as well as to salt and caustic solutions. Alloy 400 is a solid solution alloy that can only be hardened by cold working. This nickel alloy exhibits characteristics like good corrosion resistance, good weldability and high strength. A low corrosion rate in rapidly flowing brackish or seawater combined with excellent resistance to stress-corrosion cracking in most freshwaters, and its resistance to a variety of corrosive conditions led to its wide use in marine applications and other non-oxidizing chloride solutions. This nickel alloy is particularly resistant to hydrochloric and hydrofluoric acids when they are de-aerated. As would be expected from its high copper content, alloy 400 is rapidly attacked by nitric acid and ammonia systems. Monel 400 has great mechanical properties at subzero temperatures, can be used in temperatures up to 1000° F, and its melting point is 2370-2460° F. However, alloy 400 is low in strength in the annealed condition so, a variety of tempers may be used to increase the strength.

13.5.4.2 ALLOY K-500 ALTERNATIVE MONEL K500 – (PPT HRD) UNS N05500 Other common names: Alloy K500

K500 is a precipitation-hardenable nickel-copper alloy that combines the excellent corrosion resistance characteristic of Monel 400 with the added advantage of greater strength and hardness. These amplified properties, strength and hardness, are obtained by adding aluminum and titanium to the nickel-copper base and by a thermal processing used to effect precipitation, typically called age hardening or aging. When in the age-hardened condition, Monel K-500 has a greater tendency toward stress-corrosion cracking in some environments than Monel 400. Alloy K-500 has approximately three times the yield strength and double the tensile strength when compared with alloy 400. Plus, it can be further strengthened by cold working prior to precipitation hardening. The strength of this nickel steel alloy is maintained to 1200° F but stays ductile and tough down to temperatures of 400° F. Its melting range is 2400-2460° F. This nickel alloy is spark resistant and non-magnetic to -200° F. However, it is possible to develop a magnetic layer on the surface of the material during processing. Aluminum and copper may be selectively oxidized during heating, leaving a magnetic nickel rich film on the outside. Pickling or bright dipping in acid can remove this magnetic film and restore the non-magnetic properties. Corrosion Resistant Monel K-500 The corrosion resistance of alloy K-500 is substantially equivalent to that of alloy 400 except that when in the age-hardened condition, nickel alloy K-500 has a greater tendency toward stress-corrosion cracking in some environments. Monel K-500 has been found to be resistant to a sour-gas environment. The combination of very low corrosion rates in high-velocity sear water and high strength make alloy K-500 particularly suitable for shafts of centrifugal pumps in marine service. In stagnant or slow-moving sea water, fouling may occur followed by pitting but this pitting slows down after a fairly rapid initial attack. What are the characteristics of Monel K500? • Corrosion resistance in an extensive range of marine and chemical environments. From pure water to non-oxidizing mineral acids, salts and alkalis. • Excellent resistance to high velocity sea water • Resistant to a sour-gas environment • Excellent mechanical properties from sub-zero temperatures up to about 480C • Non-magnetic alloy

13.5.4.3 ALLOY R-405 – (FREE MACHINING VERSION OF 400 W ADDITION OF SULFUR) UNS N04405

R405 is the free machining version of Monel 400. It is a nickel-copper alloy with a controlled amount of sulfur added to provide sulfide inclusions that act as chip breakers during machining. Like Monel 400, alloy R-405 is resistant to sea water and steam at high temperatures as well as to salt and caustic solutions. Monel R405 is a solid solution alloy that can only be hardened by cold working. This nickel alloy exhibits characteristics like good corrosion-resistance, good weldability and high strength. A low corrosion rate in rapidly flowing brackish or seawater combined with excellent resistance to stress corrosion cracking in most freshwaters, and its resistance to a variety of corrosive conditions led to its wide use in marine applications and other non-oxidizing chloride solutions. This nickel steel alloy is particularly resistant to hydrochloric and hydrofluoric acids when they are de-aerated. As would be expected from its high copper content, alloy R-405 is rapidly attacked by nitric acid and ammonia systems. Corrosion Resistant Monel R-405 As with alloy 400, Monel R-405 is virtually immune to chloride ion stress corrosion cracking in typical environments. Generally, its corrosion resistance is very good in reducing environments, but poor in oxidizing conditions. It is not useful in oxidizing acids, such as nitric acid and nitrous. Nevertheless, it is resistant to most alkalis, salts, waters, food products, organic substances and atmospheric conditions at normal and elevated temperatures. Monel 400 and R-405 offer about the same corrosion resistance as nickel but with higher maximum working pressures and temperatures and at a lower cost due to its superior ability to be machined. What are the characteristics of Monel R405? Characteristics are essentially the same as those of Monel 400 such as: • Good machinability and is recommended for use with automatic screw machines • Resistant to seawater and steam at high temperatures • Excellent resistance to rapidly flowing brackish water or seawater • Excellent resistance to stress corrosion cracking in most freshwaters • Particularly resistant to hydrochloric and hydrofluoric acids when they are de-aerated • Offers some resistance to hydrochloric and sulfuric acids a modest temperatures and concentrations, but is seldom the material of choice for these acids • Excellent resistance to neutral and alkaline salt • Resistance to chloride induced stress corrosion cracking • High resistance to alkalis In what applications is Monel R-405 used? Alloy R-405 is chiefly used for automatic-screw-machine stock and it not generally recommended for other applications. Screw machine stock for fasteners and similar high production run items. • Meter and valve parts • Fasteners • Screw machine products

13.5.5 INCONEL (NICKEL CHROMIUM ALLOY)

13.5.5.1 ALLOY 600 ALTERNATIVE INCONEL 600 UNS Number N06600 Other common names: Alloy 600

600 is a nickel-chromium alloy used for applications that require corrosion and high temperature resistance. This nickel alloy was designed for service temperatures from cryogenic to elevated temperatures in the range of 2000° F. It is non-magnetic, has excellent mechanical properties, and presents the desirable combination of high strength and good weldability under a wide range of temperatures. The high nickel content in Inconel 600 enables it to retain considerable resistance under reducing conditions, makes it resistant to corrosion by a number of organic and inorganic compounds, gives it excellent resistance to chloride-ion stress-corrosion cracking and also provides excellent resistance to alkaline solutions. Typical applications of this nickel alloy include the chemical, pulp and paper, aerospace, nuclear engineering and heat treating industries. What are the characteristics of Inconel 600? • Resistant to a wide range of corrosive media. • Virtually immune to chlorine ion stress corrosion cracking • Non-magnetic • Excellent mechanical properties • High strength and good weldability under a wide range of temperatures In what applications is Inconel 600 used? • Chemical industry • Aerospace • Heat treating industry • Pulp and paper industry • Food processing • Nuclear Engineering • Gas turbine components Fabrication with Inconel 600 Alloy 600 can be both hot formed and cold formed using typical processes. Hot working should be performed between 1600° F and 2250° F avoiding any work between1200-1600° F because the ductility decreases in this temperature range. Welding Alloy 600 can be achieved via shielded metal-arc welding, TIG, and MIG. 13.5.5.2 ALLOY 601 ALTERNATIVE INCONEL 601 UNS Number N06601 Other common names: Alloy 601 Inconel 601 is a nickel-chromium alloy used for applications that require resistance to corrosion and heat. This nickel alloy stands out due to its resistance to high temperature oxidation, remaining highly resistant to oxidation through 2200° F. Alloy 601 develops a tightly adherent oxide scale which resists spalling even under conditions of severe thermal cycling. This nickel alloy has good high temperature strength, and retains its ductility after long service exposure. It has good resistance to aqueous corrosion, high mechanical strength, and is readily formed, machined and welded. Inconel 601’s properties make it a material of broad utility in fields like thermal processing, chemical processing, pollution control, aerospace, and power generation. However, alloy 601 is not suggested for use in strongly reducing, sulfur bearing environments. What are the characteristics of Inconel 601? • Outstanding oxidation resistance to 2200° F • Resists spalling even under severe thermal cycling conditions • Highly resistant to carburization • Good creep rupture strength • Metallurgical stability

13.5.5.3 ALLOY 625 ALTERNATIVE INCONEL 625 UNS Number N06625Other common names: Alloy 625

625 is a corrosion and oxidation resistant nickel alloy that is used both for its high strength and outstanding aqueous corrosion resistance. Its outstanding strength and toughness is due to the addition of niobium which acts with the molybdenum to stiffen the alloy’s matrix. Alloy 625 has excellent fatigue strength and stress-corrosion cracking resistance to chloride ions. This nickel alloy has excellent weldability and is frequently used to weld AL-6XN. This alloy resists a wide range of severely corrosive environments and is especially resistant to pitting and crevice corrosion. Some typical applications Inconel 625 is used in are chemical processing, aerospace and marine engineering, pollution-control equipment, and nuclear reactors. What are the characteristics of Inconel 625? • High creep-rupture strength • Oxidation resistant to 1800° F • Seawater pitting and crevice corrosion resistant • Immune to chloride ion stress corrosion cracking • Non-magnetic In what applications is Inconel 625 used? • Aircraft ducting systems • Aerospace • Jet engine exhaust systems • Engine thrust-reverser systems • Specialized seawater equipment • Chemical process equipment Fabrication with Inconel 625 Alloy 625 has excellent forming and welding characteristics. It may be forged or hot worked providing temperature is maintained in the range of about 1800-2150° F. Ideally, to control grain size, finish hot working operations should be performed at the lower end of the temperature range. Because of its good ductility, alloy 625 is also readily formed by cold working. However, the alloy does work-harden rapidly so intermediate annealing treatments may be needed for complex component forming operations. In order to restore the best balance of properties, all hot or cold worked parts should be annealed and rapidly cooled. This nickel alloy can be welded by both manual and automatic welding methods, including gas tungsten arc, gas metal arc, electron beam and resistance welding. It exhibits good restraint welding characteristics.

13.5.5.4 ALLOY 718 ALTERNATIVE INCONEL 718 UNS Number N07718 ASTM B637, B 670, B 906 – NACE MR-01-75 Other common names: Alloy 718, Haynes® 718, Nicrofer® 5219, Allvac® 718, Altemp® 718

718 is a nickel-chromium-molybdenum alloy designed to resist a wide range of severely corrosive environments, pitting and crevice corrosion. This nickel steel alloy also displays exceptionally high yield, tensile, and creep-rupture properties at high temperatures. This nickel alloy is used from cryogenic temperatures up to long term service at 1200° F. One of the distinguishing features of Inconel 718’s composition is the addition of niobium to permit age hardening which allows annealing and welding without spontaneous hardening during heating and cooling. The addition of niobium acts with the molybdenum to stiffen the alloy’s matrix and provide high strength without a strengthening heat treatment. Other popular nickel-chromium alloys are age hardened through the addition of aluminum and titanium. This nickel steel alloy is readily fabricated and may be welded in either the annealed or precipitation (age) hardened condition. This superalloy is used in a variety of industries such as aerospace, chemical processing, marine engineering, pollution-control equipment, and nuclear reactors. What are the characteristics of Inconel 718? • Good mechanical properties – tensile, fatigue and creep-rupture • Yield tensile strength, creep, and rupture strength properties are exceedingly high • Highly resistant to chloride and sulfide stress corrosion cracking • Resistant to aqueous corrosion and chloride ion stress corrosion cracking • High temperature resistant • Age-hardenable with a unique property of slow aging response that permits heating and cooling during annealing without the danger of cracking. • Excellent welding characteristics, resistant to postweld age cracking.