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Aluminum	0.2 - 0.8
Boron	0.006 max
Carbon	0.08 max
Chromium	17 - 21
Cobalt	1 max
Copper	0.3 max
Iron	Balance
Manganese	0.35 max
Molybdenum	2.8 - 3.3
Nickel	50 - 55
Niobium	4.75 - 5.5
Phosphorus	0.015 max
Silicon	0.35 max
Sulphur	0.015 max
Titanium	0.65 - 1.15

Principal Design Features		This is a high-strength, high-temperature resistant and corrosion resistant nickel-chromium alloy. It is suitable for use at cryogenic temperatures and also for use in air up to 1300 F. The alloy is readily worked and can be age-hardened.

Applications		Applications include gas turbine hot section components and cryogenic storage tanks.

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 steels. 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. 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. Tools should have a positive rake angle. Cutting speeds and feeds are in the following ranges: 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. Heavy-duty, high-speed steel drills with a heavy web are recommended. 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. Slow surface speed, as 8-10 feet/minute, are best for drilling. 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 5 to 15 feet per minute and feed of 0.001"-0.004" per cutting tooth. Grinding: The alloy should be wet ground and aluminum oxide wheels or belts are preferred.

Forming		This 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.

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. 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 60 amps for thin material (0.062" thick) up to 140 amps for material of 1/2" and thicker. It is best to weave 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 20- 23 with a current of 110-130 amps and a wire feed of 250-275 inches per minute. For Spray-Transfer GMAW voltage of 26 to 33 and current in the range of 175-300 amps with wire feed rate of 200-350 inches per minute are typical. 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.

Heat Treatment		The alloy is age-hardenable (see under "Aging") and can be annealed at 1900 F followed by air cooling.

Forging		Forging is done in the range of 2050 F to 1700 F. Final reductions of 20% for open die work and 10% for closed die are desired to maintain proper grain structure and finishing temperatures should be in the 1750 F - 1700 F range.

Hot Working		Hot working may be done in the temperature range of 2050 F to 1650 F. It is important to reheat the alloy if hot working temperatures fall below 1650 F.

Cold Working		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".

Annealing		Annealing may be done at 1900 F followed by rapid air cooling.

Aging		Two slightly different aging heat treatments are available. 1. 1800 F anneal and age at 1325 F for 8 hours, then furnace cool to 1150 F and hold at that temperature for 10 hours, then air cool. This is the optimum treatment for the highest room temperature strength and the best rupture properties. 2. 1925 F anneal and age at 1400 F, furnace cool to 1200 F and hold there for 10 hours, furnace cool to 1200 F and hold for 10 hours, then air cool. This treatment will give the best transverse ductility, especially in heavy sections. However it does tend to promote notch brittleness.

Hardening		Cold work will cause an increase in both hardness and strength. The alloy may also be age-hardened -- see "Heat Treat".

Other Mechanical Props		Impact strength values for Charpy V-Notch: At room temperatures: 20.5 ft. lbs. At minus 320 F: 19 ft. lbs.

Physical Data : [top]

Density (lb / cu. in.)	0.29
Specific Gravity	7.98
Specific Heat (Btu/lb/Deg F - [32-212 Deg F])	0.104
Electrical Resistivity (microhm-cm (at 68 Deg F))	753
Melting Point (Deg F)	2420
Poissons Ratio	0.284
Thermal Conductivity	77
Mean Coeff Thermal Expansion	7.3
Magnetic Permeability	1.001
Modulus of Elasticity Tension	29

There is no Mechnical data available for this grade.

[top]
Nickel - www.nidi.org

Copper - www.copper.org

Titanium - www.titanium.org

Steel Lynx - www.mlc.lib.mi.us/~stewarca/steelynx.html

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