Monel 401 Alloy N04401 Alloy

Monel 401 Alloy copper-nickel alloy designed for specialized electrical and electronic applications. It has a very low temperature coefficient of resistance and medium-range electrical resistivity. Used for wire-wound precision resistors and bi-metal contacts. Monel 401 is higher in copper content than Monel 400 for better electrical properties.Monel 401 Alloy Machinability

Conventional machining techniques used for iron based alloys may be used. This alloy does work-harden during machining and has higher strength and “gumminess” not typical of steel. Heavy duty machining equipment and tooling should be used to minimize chatter or work-hardening of the alloy ahead of the cutting. Most any commercial coolant may be used in the machining operations. Water-base coolants are preferred for high speed operations such as turning, grinding, or milling. Heavy lubricants work best for drilling, tapping, broaching or boring.

Monel 401 Alloy Turning: Carbide tools are recommended for turning with a continuous cut. High-speed steel tooling should be used for interrupted cuts and for smooth finishing to close tolerance. Tool should have a positive rake angle. Cutting speeds and feeds are in the following ranges: For High-Speed Steel Tools For Carbide Tooling Depth Surface Feed Depth Surface Feed of cut speed in inches of cut speed in inches inches feet/min. per rev. inches feet/min.

Monel 401 Alloy Milling: To obtain good accuracy and a smooth finish it is essential to have rigid machines and fixtures and sharp cutting tools. High-speed steel cutters such as M-2 or M-10 work best with cutting speeds of 60 to 80 feet per minute and feed of 0.005″-0.008″ per cutting tooth.

Monel 401 Alloy Drilling: Steady feed rates must be used to avoid work hardening due to dwelling of the drill on the metal. Rigid set-ups are essential with as short a stub drill as feasible. Conventional high-speed steel drills work well. Feeds vary from 0.0007 inch per rev. for holes of less than 1/16″ diameter, 0.003 inch per rev. for 1/4″ dia., to 0.010 inch per rev. for holes of 7/8″diameter. Surface speeds of 45-55 feet/minute, are best for drilling.

Monel 401 Alloy Grinding: The alloy should be wet ground and aluminum oxide wheels or belts are preferred.

Monel 401 Alloy Forming
Monel 401 alloy has good ductility and may be readily formed by all conventional methods. Because the alloy is stronger than regular steel it requires more powerful equipment to accomplish forming. Heavy-duty lubricants should be used during cold forming. It is essential to thoroughly clean the part of all traces of lubricant after forming as embrittlement of the alloy may occur at high temperatures if lubricant is left on.

Monel 401 Alloy Welding
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.

Monel 401 Alloy 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.

Monel 401 Alloy 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.

Monel 401 Alloy Cold Working
Cold forming of Monel 401 Alloy 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 steel ( 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″.

Monel 401 Alloy Specification:

ASME SB163 Standard Specification for Seamless Nickel and Nickel Alloy Condenser and Heat-Exchanger Tubes

ASME SB165 Standard Specification for Nickel-Copper Alloy (UNS N04400)* Seamless Pipe and Tube

ASME SB167 Standard Specification for Nickel-Chromium-Iron Alloys, Nickel-Chromium-Cobalt-Molybdenum Alloy (UNS N06617),and Nickel-Iron-Chromium-Tungsten Alloy (UNS N06674) Seamless Pipe and Tube

ASME SB407 Standard Specification for Nickel-Iron-Chromium Alloy Seamless Pipe and Tube

ASME SB423 Standard Specification for Nickel-Iron-Chromium-Molybdenum-Copper Alloy (UNS N08825, N08221, and N06845) Seamless Pipe and Tube

ASME SB444 Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloys (UNS N06625 and UNS N06852) and Nickel-Chromium-Molybdenum-Silicon Alloy (UNS N06219) Pipe and Tube

ASME SB622 Standard Specification for Seamless Nickel and Nickel-Cobalt Alloy Pipe and Tube

ASME SB668 UNS N08028 Seamless Pipe and Tube

ASME SB690 Standard Specification for Iron-Nickel-Chromium-Molybdenum Alloys (UNS N08366 and UNS N08367) Seamless Pipe and Tube

ASME SB729 Standard Specification for seamless UNS N08020, UNS N08026, and UNS N08024 nickel alloy pipe and Tube

Monel 401 Alloy Chemical Composition, %

Monel 401 Alloy Physical Properties: