Nickel-based super alloy: Monel 401 (UNS N04401)
What is Monel 401?
Monel 401 (also known as “401 alloy”) is named UNS N04401, a copper nickel alloy designed for special electrical and electronic applications. It has a very low temperature coefficient of resistance and a medium range of resistivity. Alloy 401 can be easily welded by gas tungsten arc welding (GTAW) or resistance welding. Monel 401 is usually supplied in the form of wire, mainly for wound precision resistors and bimetallic contacts. Monel 401 is a ductile Copper Nickel alloy with a very low coefficient of electrical resistivity and resistance to a wide variety of corrosive conditions. Like with commercially pure Nickel, Monel 401 is low in strength in the annealed condition and can only be cold worked to a maximum of 120 KSI.
Super alloy Monel 401 has high contents of copper than that of super alloy Monel 400.
Monel 401 wires
Equivalent Grades of Monel 401 (UNS N04401)
Chemical Composition of Monel 401 (UNS N04401)
Physical Properties of Monel 401 (UNS N04401)
|Density||Thermal conductivity||Thermal coefficient of Resistance||Electrical Resistivity||Specific heat capacity|
|g/cm3||W/m. °C||ppm/°C||µΩ·m||（J/kg/℃ ）|
Mechanical Properties of Monel 401 (UNS N04401)
|Tensile Strength, min.||Yield Strength, min.||Elongation||Hardness|
Specifications of Monel 401 (UNS N04401)
|Rod, Bar, Wire, Forgings||ASTM B163/ASME SB163, DIN 17471|
|Plate, Sheet, Strip||ASTM B127/ASME SB127, DIN 17750|
|Pipe, Tube||ASTM B163/ASME SB163, ASTM B725/ASME SB725, ASTM B775/ASME SB775, ASTM B751/ASME SB751, DIN17751|
|Others||ASTM B366/ASME SB366(Pipe fittings), DIN 17743|
The machinability of Monel 401
- Traditional machining techniques used on ferroalloys can be used for this alloy.
Welding of Monel 401
Alloy 401 is easy to weld into thin sheets automatically. Gas tungsten arc welding is a common welding process. Resistance welding is a satisfactory method for this alloy. The commonly used welding methods work well with this alloy. Matching alloy filler metal should be used. If matching alloy is not available then the nearest alloy richer in the essential chemistry (Ni, Co, Cr, Mo) should be used. All weld beads should be slightly convex. It is not necessary to use preheating. Surfaces to be welded must be clean and free from oil, paint or crayon marking. The cleaned area should extend at least 2″ beyond either side of a welded joint.
- Gas-Tungsten Arc Welding: DC straight polarity (electrode negative) is recommended. Keep as short an arc length as possible and use care to keep the hot end of filler metal always within the protective atmosphere. Shielded Metal-Arc Welding: Electrodes should be kept in dry storage and if moisture has been picked up the electrodes should be baked at 600 F for one hour to insure dryness. Current settings vary from 50 amps for material 0.062″ thick up to 190 amps for material of 1/2″ and thicker. It is best to weave the the electrode slightly as this alloy weld metal does not tend to spread. Cleaning of slag is done with a wire brush (hand or powered). Complete removal of all slag is very important before successive weld passes and also after final welding.
- Gas Metal-Arc Welding: Reverse-polarity DC should be used and best results are obtained with the welding gun at 90 degrees to the joint. For Short-Circuiting-Transfer GMAW a typical voltage is 19-25 with a current of 100-175 amps and a wire feed of 225-400 inches per minute. For Spray-Transfer GMAW voltage of 26 to 33 and current in the range of 200-350 amps with wire feed rate of 200-500 inches per minute, depending on filler wire diameter.
- Submerged-Arc Welding: Matching filler metal, the same as for GMAW, should be used. DC current with either reverse or straight polarity may be used. Convex weld beads are preferred.
Hot working of Monel 401
- Hot working can be carried out if necessary.
Cold working of Monel 401
Cold working can be carried out with standard tooling and soft mold materials for better finish. Cold forming may be done using standard tooling although plain carbon tool steels are not recommended for forming as they tend to produce galling. Soft die materials (bronze, zinc alloys, etc.) minimize galling and produce good finishes, but die life is somewhat short. For long production runs the alloy tool steels ( D-2, D-3) and high-speed steels (T-1, M-2, M-10) give good results especially if hard chromium plated to reduce galling. Tooling should be such as to allow for liberal clearances and radii. Heavy duty lubricants should be used to minimize galling in all forming operations. Bending of sheet or plate through 180 degrees is generally limited to a bend radius of 1 T for material up to 1/8″ thick and 2 T for material thicker than 1/8″.
Hardening of Monel 401
- Hardens by cold working only.
- Monel 401 alloy should be annealed at 760 ° C (1400 ° f) for one hour to recover from cold working.
- Not heat treatable except for annealing after cold working.
Application areas of nickel-based alloy monel 401 (UNS N04401):
- Wire wound resistors.
- Bimetal contacts.
- Electric and electronic applications.
- Marine engineering.
- Chemical and hydrocarbon processing equipment.
- Gasoline and freshwater tanks.
- Crude petroleum stills.
- De-aerating heaters.
- Boiler feed water heaters and other heat exchangers.
- Valves, pumps, shafts and fasteners.
- Industrial heat exchangers.
- Chlorinated solvents.
- Crude oil distillation towers.
- Piping system.
- Heat exchange tubes.
- Pipe fittings.
Variety specifications and supply status of Nickel-based super alloy: Monel 401 (UNS N04401):
Yaang Pipe Industry can produce various specifications of Monel 401 seamless pipe, Monel 401 steel plate, Monel 401 round bar, Monel 401 forgings, Monel 401 flange, Monel 401 pipe fittings, Monel 401 welded pipe, Monel 401 steel strip, Monel 401 wire and supporting welding materials.
- Seamless pipe: solid solution + acid white, length can be set;
- Plate: solid solution, pickling, trimming;
- Welded pipe: solid solution acid white + RT% flaw detection;
- Forging: annealing + car polish; Bars are forged and rolled, surface polished or car polished;
- Strips are delivered after cold rolling, solid solution soft state, and deoxidized;
- Wire rods are finely ground in solid solution pickled disk or straight strips, solid solution straight strips Delivery in light state.
Source: China Monel 401 Flanges Manufcturer – Yaang Pipe Industry (www.steeljrv.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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