The following specifications cover Super Alloy Discaloy(tm)

• AMS 5733
• ASTM A453 (662)
• ASTM A638 (662)
• UNS S66220

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Property Results

Chemistry Data : [top]

Aluminum		0.35 max
Boron		0.01 - 0.001
Carbon		0.08 max
Chromium		12 - 15
Copper		0.5 max
Iron		Balance
Manganese		1.5 max
Molybdenum		2.5 - 3.5
Nickel		24 - 28
Phosphorus		0.04 max
Silicon		1 max
Sulphur		0.03 max
Titanium		1.55 - 2

Principal Design Features		An iron-base high temperature, high strength alloy containing nickel and chromium. The alloy is age-hardenable.

Applications		Gas turbine hot section components, specifically turbine discs.

Machinability		Conventional machining techniques used for iron based alloys may be used. Machining characteristics are somewhat similar to those for the austenitic (300 Series) stainless steels. 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. Water-base coolants of premium quality are preferred. Rigid mounting of tooling and the workpiece are important to avoid "chatter" (work hardening ahead of the cut). Both carbide tools and high-speed tools may be used successfully. Carbide tooling generally permits twice, or better, the feed rate of high-speed tooling for the same depth of cut or drilling. Turning: For roughing cuts the tools should have -5 degree back rake for carbide and -10 degree back rake for high-speed steel. Normal and/or finish turning call for positive rake angles of about +10 degrees for both carbide and high-speed cutters. 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. per rev. 0.040" 0.040" 0.250" 0.250" 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 0.001 inch per rev. for holes of less than 1/16" diameter, 0.002 to 0.003 inch per rev. for 1/4" dia., 0.004 to 0.010 inch per rev. for holes of 7/8"diameter. Speeds of 10 to 25 surface 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 30 to 50 surface feet per minute and feed of 0.002-0.007 inch per cutting tooth. Grinding: The alloy should be wet ground and aluminum oxide wheels or belts are preferred.

Forming		The alloy is readily formed by conventional means.

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. Complete removal of slag is important after every weld pass and upon completion of welding. Usually this is accomplished by use of a wire brush (hand or powered). 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 (TIG): 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. Arc voltage should be in the range of 9 to 13 volts with current of 20-60 amps for thin material, 60-150 amps for material 1/8" thick or so, and 100-150 amps for material 1/4" thick. Shielded Metal-Arc Welding (SMAW): 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. Use electrode positive polarity. Current settings vary from 60 amps for 3/32" dia. rods up to 180 amps for 3/16" dia. rods. It is best to weave the electrode slightly as this alloy weld metal does not tend to spread. Metal-Arc Welding (MIG): Electrode positive polarity 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 18-22 with a current of 75-150 amps and a wire feed of 8-10 inches per minute. Submerged-Arc Welding: Generally submerged-arc welding should be avoided. This weld process involves high heat input and may lead to cracking of the alloy workpiece.

Heat Treatment		This alloy may be annealed following cold work. It also responds to age-hardening by thermal treatment.

Forging		The alloy may be hot forged. No data as to temperature range.

Hot Working		See "Forging".

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". In order to avoid "orange peel" surface effect the cold work reduction of area should be greater than 15% at any given operation. Intermediate annealing may be done, to restore ductility, during the sequence of cold forming operations.

Annealing		Solution anneal at 1850 F for 2 hours and oil quench.

Aging		Age-hardening is done by first giving a solution anneal at 1850 F for 2 hours, followed by oil quench, then 1350 F for 20 hours, air cool and lastly 1200 F for 20 hours followed by air cooling.

Hardening		See "Aging".

Physical Data : [top]

Density (lb / cu. in.)	0.29
Specific Gravity	7.97
Specific Heat (Btu/lb/Deg F - [32-212 Deg F])	0.113
Melting Point (Deg F)	2650
Thermal Conductivity	92
Mean Coeff Thermal Expansion	8.5
Modulus of Elasticity Tension	28

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Mechanical Data : [top]

MSO currently has no data available for this grade.

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