CRUCIBLE A9
(AISI A9)
Crucible A9 is an air-hardening tool steel combining some of characteristics of the 5% chromium hot-work grades (such as H13) with the high attainable hardness and compressive yield strength of the cold-work grades (such as A2). Crucible A9 is suitable for hot and cold work applications requiring high toughness, hardness, or heat check resistance, and moderate wear resistance.
Typical Chemistry
Carbon 0.50%
Manganese 0.30%
Silicon 1.00%
Chromium 5.20%
Vanadium 1.00%
Molybdenum 1.40%
Nickel 1.40%
Typical Applications
Coining Dies Extrusion Dies
Piercing Tools Punches
Heading Dies Upset Dies
Forging Dies Shear Blades
Insert Holders Trim Dies
Hardening

Critical Temperature: 1480F(805C).

Preheat: 1400/1450F(760/790C)

High Heat: 1800/1850F(980/1010C), hold 20/45 minutes at temperature.

Quench: Air or vacuum quench to hand warm, 150F(65C). Salt bath or interrupted oil may be required to attain maximum hardness in large sections. Interrupted oil quenching consists of quenching in oil until just black (1100F(540/595C)), then air cooling to hand warm, 150F(65C).

Temper: 1000/1100F(540/595C) is normally recommended. Hold one hour per inch of thickness, two hours minimum, four hours recommended. Temper twice.

Cryogenic treatments: Refrigeration treatments are generally of limited utility for materials with multiple tempers over 1000F(540C).
Typical Properties
Hardness and Impact Toughness Data
Air Cooled from 1800F(980C).
Tempering
Temp.
Hardness
Toughness,
Charpy C-notch
°F
°C
HRC
ft-lbs
Joules
900 480 56 50 68
950 510 56.5 50 68
1000 540 54.5 112 152
1050 565 52.5 134 182
1100 595 47 151 205
Air Cooled from 1850F(1010C).
Tempering
Temp.
Hardness
Toughness,
Charpy C-notch
°F
°C
HRC
ft-lbs
Joules
900 480 57 50 68
950 510 58 55 75
1000 540 56 128 174
1050 565 54 139 188
1100 595 49 140 190
Surface Treatments
Crucible A9 can be given standard surface treatments such as nitriding, titanium nitride coating, and hard chrome plating if desired.

Annealing
A. Heat to 1600F(870C), hold two hours, cool slowly, 25F(15C) per hour maximum, to below 1000F(540C), then air cool.
OR
B. Heat to 1600F(870C), hold 2 hours, cool to 1300/1400F(705/760C), hold 6 hours, then air cool.

Typical annealed hardness: 217/241 BHN

Stress Relieving
Annealed Material: 1100/1300F(595/740C), hold 2 hours, cool in still air.
Hardened Material: 50F(30C) below last tempering temperature, hold two hour, cool in still air.

Welding
Use hot-work (H13 or H12 or A8 type) tool steel filler material.
Annealed material: Preheat to 800/1000F(425/540C); maintain above 600F(315C) during welding. Allow to cool to hand warm (150F(65C)) after welding. Reanneal, or temper 1300/1400F(705/760C) for 6 hours.
Hardened material: Preheat to 100F(55C) below tempering temperature (800F(425C) minimum). Maintain over 600F(315C) during welding. Allow to cool to hand warm (150F(65C)) after welding. Retemper twice at 25/50F(15/30C) below original tempering temperature.

Physical Properties
Modulus of Elasticity ...................................................................30 psi x 106 (207 GPa)
Density .......................................................................................0.281 lb/in3 (7780 kg/m3)
Specific gravity ............................................................................................................7.78
Thermal Conductivity ................................... 15 BTU/hr/ft/°F(200F) 25.8 W/m°K(95C)
Thermal Expansion
Temperature
Range
Coefficient of Thermal
Expansion
°F
°C
in/in/°Fx10-6
mm/mm/°Cx10-6
RT/800F
RT/425
6.7
12.0
RT/1000F
RT/540
6.9
12.4
RT/1200F
RT/650
7.0
12.6
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