Nickel Alloy

Nickel and its alloys have long been indispensable across numerous industries due to their exceptional versatility and ability to form stable alloys with most metals. This adaptability makes nickel alloys a preferred choice in demanding environments where strength, corrosion resistance, and temperature stability are critical.

One of the defining characteristics of nickel alloys is their resistance to extreme pressure and high temperatures. These properties make them ideal for high-performance applications such as aerospace turbine components, nuclear reactors, and jet engine blades. Their outstanding corrosion resistance also makes them suitable for harsh marine and chemical processing environments — as seen in alloys like Monel, which is frequently used in deep-sea mining and seawater applications.

Nickel and nickel alloys are non-ferrous materials known for their high strength, durability, and excellent resistance to oxidation and chemical attack. Pure nickel itself is a bright, silver-white metal that is hard, ductile, and malleable. It serves as a robust foundation for engineering advanced alloys tailored to meet specific industrial challenges, especially where elevated temperatures and corrosive conditions prevail.

Chemical Composition of Nickel Alloys

Grade C Mn Si P S Cr Mo Cu Ni Fe Others
Alloy 400 Min - - - - - - - 28 Balance - -
Max 0.3 2.0 0.5 - 0.024 - - 34 - 2.5 -
Alloy K500 Min - - - - - - - 29 66 1.0 Al 2.7, W 0.6
Max 0.1 0.7 0.25 - 0.01 - - 29 66 1.0 -
Alloy 625 Min - - - - - 20 8 - 58 - Cb+Ta 3.15
Max 0.10 0.50 0.50 0.015 0.015 23 10 - Balance 5 Co 1.0, Ti 0.4, Al 0.4
Alloy 718 Min - - - - - 17 2.8 - 50 Balance Cb 4.75, Ti 0.65, Al 0.2
Max 0.08 0.35 0.35 0.015 0.015 21 3.3 0.30 55 Balance B 0.006, Co 1.0, Ta 0.05
Alloy 825 Min - - - - - 19.5 2.5 1.5 38 22 (~33%) Ti 0.6, Al 0.2
Max 0.05 1.0 0.5 - 0.03 23.5 3.5 3.0 46 - Ti 1.2
Alloy 20 Min - - - - - 19 2 3 32 35 Nb ≤1
Max - 2 1 - - 21 3 4 38 - -
Alloy C276 Min - - - - - 14.5 15 - 57 4 W 3, Co 2.5, V 0.35
Max 0.010 1 0.080 0.025 0.010 16.5 17 - 57 7 -

Physical Properties of Nickel Alloys

Grade Density (g/cm³) Density (lb/in³) Melting Point (°C) Melting Point (°F) Specific Gravity Tensile Strength Yield Strength Elongation
Alloy 400 8.8 0.318 - - - - - -
Alloy K500 8.45 0.305 1338 2440 - - - -
Alloy 625 - 0.305 - 2350–2460 - - - -
Alloy 718 (Solution Treated) 8.192 0.296 1370–1430 2500–2600 8.19 - - -
Alloy 718 (Solution Treated & Aged) 8.22 0.297 1370–1430 2500–2600 8.22 - - -
Alloy 825 8.14 - 1400 2550 - 80,000 psi / 550 MPa 32,000 psi / 220 MPa 30%
Alloy 20 8.05 0.291 - - - - - -
Alloy C276 8.89 0.321 1371 2500 - - - -

Mechanical Properties of Nickel Alloys

Grade Tensile Strength Yield Strength Elongation Modulus of Elasticity Hardness Poisson’s Ratio Other Properties
Alloy 400 517–620 MPa (75–90 ksi) 172–345 MPa (25–50 ksi) - 179 GPa (26,000 ksi) - 0.32 -
Alloy K500 1000 MPa (145,000 psi) 655 MPa (95,000 psi) 22% - Rockwell C: 27 - Reduction of area: 40%
Alloy 625 827 MPa (120 ksi) 414 MPa (60 ksi) 30% - - - Elongation in 2”
Alloy 718 1240 MPa (180,000 psi) 1035 MPa (150,000 psi) 12% - - - Offset 0.2%
Alloy 825 550 MPa (80,000 psi) 220 MPa (32,000 psi) 30% - - - Estimated
Alloy 20 620 MPa (89.9 ksi) 300 MPa (43.5 ksi) 41% - - - Annealed
Alloy C276 601.2 MPa (87,200 psi) 204.8 MPa (29,700 psi) 56% 205 GPa (29,700 ksi) Rockwell B: 87 - @thickness 0.0630–0.185 in, 399°F

Characteristics of Nickel Alloys

Characteristics of Nickel Alloys
High resistance to uniform attack Outstanding localized corrosion resistance Excellent stress corrosion cracking resistance
Ease of welding and fabrication High resistance to oxidation at elevated temperatures Good resistance to acids, such as sulfuric, phosphoric, nitric, and hydrochloric
Excellent mechanical properties at both extremely low and extremely high temperatures Outstanding resistance to pitting, crevice corrosion and intercrystallite corrosion Good thermal, electrical and magnetic properties

Grades of Nickel Alloys


Alloy - 400

MONEL nickel alloy is a solid solution alloy that can be hardened by the process of cold working. MONEL is a trademark of Special Metals Corporation under which a series of nickel-copper alloys are grouped. Commercially there are many types of MONEL available, such as alloy 400, alloy 401, alloy R-405, Alloy K-500 and Monel 404. The Alloy 400 alloy is also known as super alloy monel. This alloy is available in some standard shapes such as hexagon, round, tube, pipe, plate, strip, sheet and wire. The proportions of copper and nickel used to make monel are the same as that found in the nickel ore found in Ontario mines. This alloy exhibits good corrosion resistance. This datasheet will look into the chemical composition, properties and applications of Alloy 400 alloy.

Processing Alloy - 400
Machinability The machinability of MONEL 400 is difficult as it work-hardens during machining. The conventional machining techniques used on iron alloys may be used for this alloy.
Welding: Welding methods including gas-arc welding, metal-arc welding, gas-metal-arc welding and submerged-arc welding are recommended on this alloy.
Forging Forging of this alloy is to be done by controlled procedures.
Hot Working Hot working on this alloy needs to be done by choosing proper temperatures. Typical temperatures for hot working range between 648-1176째C (1200-2150째F).
Cold Working Cold working may be done using soft die materials for better finishing.
Annealing Inconel X-750 alloy is annealed at 983 to 1038째C (1800 to 2000째F) followed by cooling.
Applications 1. Marine fixtures, pumps, valves and piping systems for sea water applications. 2. Chemical plant equipment. 3. Frames for eyeglasses. 4. Aerospace applications. 5. Musical instruments.

Alloy - K500

Super alloys contain many elements in different combinations so as to achieve a desired result. They have the ability to function at very high temperatures and under severe mechanical stress, and also where high surface stability is required. They have good creep and oxidation resistance. There are three groups of alloys, namely cobalt-based, nickel-based, and iron-based alloys. Monel K-500 is an age-hardenable version of Monel 400 alloy. It has high strength and sea water corrosion resistance. The following datasheet gives more details about Monel K-500.

Processing Alloy - K500
Machinability Monel K-500 is machined in the annealed condition.
Forming Monel K-500 can be formed using standard methods in the annealed condition.
Welding: Monel K-500™ is welded using all conventional methods in the annealed condition. After this process, stress-relief annealing is performed for the finished weldment.
Heat Treatment Monel K-500™ is heat treated by annealing. It can also be precipitation-hardened by performing aging heat treatment.
Forging Monel K-500 is forged at 1038 to 1149°C (1900 to 2100°F) followed by quenching in water.
Hot Working Monel K-500 is hot worked at 872 to 1149°C (1600 to 2100°F) followed by quenching in water. It should not be cooled below 872°C (1600°F).
Cold Working Monel K-500™ can be cold worked using standard methods.
Annealing Monel K-500 is annealed at 1038°C (1900°F) followed by quenching in water.
Aging Annealed or slightly cold-worked material is age-hardened at 608°C (1125°F ) for 16 h followed by cooling in a furnace. Severely cold-worked material is aged at 538°C (1000°F) for 6 h followed by cooling in a furnace.
Applications Super alloy Monel K-500 is used in impellers, sea water pump shafts, and oil well industry for valve trim and other components.

Alloy - 625

Super alloys contain many elements in different combinations so as to achieve a desired result. They have the ability to function at very high temperatures and under severe mechanical stress, and also where high surface stability is required. They have good creep and oxidation resistance. There are three groups of alloys, namely cobalt-based, nickel-based, and iron-based alloys. Monel K-500 is an age-hardenable version of Monel 400 alloy. It has high strength and sea water corrosion resistance. The following datasheet gives more details about Monel K-500.

Processing Alloy - 625
Machinability Monel K-500 is machined in the annealed condition.
Forming Monel K-500 can be formed using standard methods in the annealed condition.
Welding: Monel K-500™ is welded using all conventional methods in the annealed condition. After this process, stress-relief annealing is performed for the finished weldment.
Heat Treatment Monel K-500™ is heat treated by annealing. It can also be precipitation-hardened by performing aging heat treatment.
Forging Monel K-500 is forged at 1038 to 1149°C (1900 to 2100°F) followed by quenching in water.
Hot Working Monel K-500 is hot worked at 872 to 1149°C (1600 to 2100°F) followed by quenching in water. It should not be cooled below 872°C (1600°F).
Cold Working Monel K-500™ can be cold worked using standard methods.
Annealing Monel K-500 is annealed at 1038°C (1900°F) followed by quenching in water.
Aging Annealed or slightly cold-worked material is age-hardened at 608°C (1125°F ) for 16 h followed by cooling in a furnace. Severely cold-worked material is aged at 538°C (1000°F) for 6 h followed by cooling in a furnace.
Applications Super alloy Monel K-500 is used in impellers, sea water pump shafts, and oil well industry for valve trim and other components.

Alloy - 718

Corrosion Resistance Properties of Alloy - 718

Based on the high chrome and molybdenum concentrations, UNS N07718 has a good resistance in many media against abrasive and local corrosion such as pitting. By virtue of its high nickel content, UNS N07718 also has good resistance against stress corrosion cracking.

Processing Alloy - 718
Heat treatment Workpieces must be clean and free of any contaminants before and during heat treatment. Sulfur, phosphor, lead and other low-melting-point metals can lead to damage when heat treating UNS N07718. Sources of such contaminants include marking and temperature-indicating paints and crayons, lubricating grease and fluids, and fuels. Heat treatments can be carried out in gas fired, oil fired or electric furnaces in air, under vacuum or inert gas atmosphere. Fuels should contain as little sulfur as possible. Natural gas should contain less than 0.1 wt.-% of sulfur. Heating oil with a sulfur content of maximum 0.5 wt.-% is also suitable with a slightly oxidizing atmosphere. The workpieces may not be contacted directly by flames.
Hot working The hot working should generally be conducted after the homogenization with subsequent cooling in air. It should be done evenly in order to receive a homogeneous structure and to prevent the formation of a duplex grain structure.
Cold working Cold working should take place in the solution-annealed condition. The material has a higher work hardening rate than austenitic stainless steels. This must be taken into account during design and selection of forming tools and equipment and during the planning of the forming processes.
Descaling and pickling Oxides from UNS N07718 and discoloration adjacent to welds are more adherent than on stainless steels. Grinding with very fine abrasive belts or discs is recommended. Care should be taken to prevent tarnishing. Before pickling which may be performed in a nitric/hydrofluoric acid mixture with proper control of pickling time and temperature, the surface oxide layer must be broken up by abrasive blasting or by carefully performed grinding.
Machining While UNS N07718 in the solution-annealed condition is easier to process and the strain on tools is less, better surface quality is achieved in the hardened condition. The best results in terms of the surface quality of the finished product are achieved by pre-treatment before hardening and by finishing in the hardened condition.
Welding UNS N07718 can be welded in a number of different welding processes. Wherever the inert gas welding process is used, impulse technology is preferable. The material should be in the solution-annealed condition for welding, and should be free of scale, grease and markings. When welding the root, care should be taken to achieve best quality root backing (e.g. argon 4.6), so that the weld is free from oxides after welding the root. Any temper colors must be removed, preferably using a stainless steel brush, while the welding seam is still hot.
Applications it has been used in jet engine and high-speed airframe parts, including wheels, fasteners, instrumentation parts, bolts, spacers and buckets. It is also used to engineer components for liquid-fuelled rockets, rings and casings, as well as various formed sheet metal parts for turbine engines, both aircraft and land-based. At the other end of the temperature scale, INCONEL alloy 718 is also used in cryogenic tankage.

Alloy - 825

Corrosion Resistance Properties of Alloy - 825

UNS N08825 is a versatile engineering alloy with resistance to corrosion in acids and alkalis under both oxidizing and reducing conditions. The high nickel content gives the alloy virtual immunity to stress corrosion cracking. The corrosion resistance in various media like sulfuric, phosphoric, nitric and organic acids is good, as well as the corrosion resistance in alkalis or ammoniac, sea water and caustic chloride. The versatility of UNS N08825 is illustrated by its use in nuclear fuel element dissolvers where a variety of corrosive media, e. g. sulfuric and nitric acids and sodium hydroxide, are handled in the same equipment.

Processing Alloy - 825
Fabrication Incoloy 825 can be readily hot or cold worked. Hot working should be in the range 870 – 1180°C, finishing at 870 – 980°C. For maximum corrosion resistance hot worked parts should be stabilise annealed before use. The alloy is easier to cold form than stainless steels.
Machinability Machining Alloy 825 should be machined in the annealed temper. As the alloy is prone to work-hardening, low cutting speeds and appropriate feed rates should be used and the tool should be engaged at all times. Sufficient chip depths are important to get below the work-hardened surface layer. The optimum dissipation of heat through the use of large amounts of appropriate, preferably water containing cooling lubricants is crucial for a stable machining process.
Welding: The alloy is readily weldable by the normal processes (GMAW (MIG), GTAW (TIG), SMAW (manual), SAW). The joint must be clean to avoid contamination of the weld pool.
Heat Treatment Incoloy 825 is stabilise annealed at 940°C. The softest structure is obtained at 980°C. Sections heavier than sheet, strip and wire should be quenched to avoid sensitisation.
Hot working UNS N08825 may be hot-worked in the temperature range 1,150 to 900 °C (2,100 to 1,650 °F) with subsequent rapid cooling down in water or by using air. The workpieces should be placed in the furnace heated to hot working temperature in order to heat up. Once the temperature has equalised, a retention time of 60 minutes for each 100 mm (4 in) of workpiece thickness is recommended. After this, the workpieces should be removed immediately and formed during the stated temperature window. If the material temperature falls below the minimum hot working temperature, the workpiece must be reheated. Heat treatment after hot working is recommended in order to achieve optimum properties and corrosion resistance.
Cold working Cold working should be carried out on annealed material. UNS N08825 has a higher work hardening rate than austenitic stainless steels. This must be taken into account during design and selection of forming tools and equipment and during the planning of the forming processes. Intermediate annealing may be necessary at high degrees of cold working deformation. After cold working with more than 15 % of deformation the material should be soft annealed.
Applications Applications of Alloy 825 include chemical processing, pollution control, oil and gas recovery, acid production, pickling operations, nuclear fuel reprocessing, and handling of radioactive wastes.

Alloy - 20

Corrosion Resistance Properties of Alloy - 20

Alloy 20 has excellent corrosion resistance to sulphuric, phosphoric and organic acids and to aqueous solutions of their salts. Resistance to nitric acid is also good. Due to the controlled chemical composition, the alloy also has excellent resistance to such forms of corrosion as intergranular corrosion and stress corrosion. The molybdenum content ensures good resistance to pitting and crevice corrosion. Optimum corrosion resistance can only be obtained if the material is in the correct metallurgical condition and clean.

Processing Alloy - 20
Welding: UNS N08020 can be welded by shielded metal arc welding, gas tungsten arc welding and gas metal arc welding. The filler metal is usually an INCONEL alloy.
Hot Working UNS N08020 may be hot-worked in the range 1150 to 900 °C (2100 to 1650 °F). The final hot-working temperature must not exceed 950 °C (1740 °F). Cooling should be by water quenching or as fast as possible.
Cold Working Cold working should be carried out on annealed material. UNS N08020 has a work-hardening rate similar to that of austenitic stainless steel and the forming equipment must be adapted accordingly. When cold working is performed, interstage annealing may become necessary. After cold reductions of more than 15 %, a final stabilizing anneal is required before use.
Heat Treatment Soft or stabilizing annealing should be carried out in the temperature range 920 to 960 °C (1690 to 1760 °F), preferably at about 950 °C (1740 °F). Water quenching or rapid air cooling is recommended for thicknesses above about 3 mm (1/8 in.) and is essential for maximum corrosion resistance.
Machining UNS N08020 should be machined in annealed condition. The alloy’s high work-hardening rate should be considered, i.e. only low surface cutting speeds are possible compared with low-alloy standard austenitic stainless steel. Tools should be engaged at all times. Heavy feeds are important in getting below the work-hardened ‘skin’.
Applications Applications of Alloy 20 include chemical processing, pollution control, oil and gas recovery, acid production, pickling operations, nuclear fuel reprocessing, and handling of radioactive wastes.

Alloy - C276

Corrosion Resistance Properties of Alloy - C276

UNS N10276 can be used in many chemical processes with both oxidizing as well as reducing media. The high chrome and molybdenum concentrations make the alloy resistant to chloride ion attacks. The tungsten content further increases this resistance. UNS N10276 is one of the few materials that are resistant against chlorine gas, hypochlorite and chlorine dioxide solutions. The alloy is characterized by excellent resistance against concentrated solutions of oxidizing salts (such as iron III and copper chloride).

Processing Alloy - C276
Machinability UNS N10276 should be machined in the heat-treated condition. For reasons of the considerably increased tendency to work hardening in comparison to austenitic stainless steels, a low-cut speed at a feed level that is not too high should be selected and the cutting tool should be engaged at all times. An adequate depth of cut is important in order to cut below the previously formed strain-hardened zone. Optimum heat dissipation through the use of large quantities of suitable, preferably aqueous, lubricants has considerable influence on a stable machining process.
Hot Forming UNS N10276 should be hot-formed in a temperature range of 950 to 1,200 °C (1,742 to 2,192 °F) with subsequent rapid cooling in water or in air. Heat treatment after hot-working is recommended in order to achieve optimal corrosion behavior. For heating up, workpieces should be placed in a furnace that is already heated up to the target value.
Cold Forming The workpieces should be in the annealed condition for cold working. UNS N10276 has significantly higher cold forming properties than the widely used austenitic stainless steels. This must be taken into account during design and selection of forming tools and equipment and during the planning of forming processes. Intermediate annealing is necessary for major cold-working treatment. When cold forming of > 15 %, final solution annealing must be conducted.
Welding: UNS N10276 is capable of being welded by the commonly used welding methods. During the welding process excessive input of heat should be avoided. For corrosive applications this alloy is capable of being used in the “as-welded” condition without the need for more heat treatment.
Heat Treatment UNS N10276 is solution heat treated at 1121°C (2050°F) and then quenched rapidly. In case of forging or hot forming, the parts should first be solution heat treated before usage.
Applications Paper and pulp industry, e.g. for digestion and bleaching tanks ∙ Washers, agitators and wet ventilators in flue gas desulfurization systems ∙ Equipment and components for acid gas applications ∙ Reactors for acetic acid production ∙ Sulfuric acid coolers ∙ Methylene diphenyl isocyanate (MDI) ∙ Manufacturing and processing of contaminated phosphoric acid.