PEERLESS A
(AISI H21)
Peerless A is designed for tools which will run hot, at operating temperatures between about 600F and 1100F. The tools should not be water cooled in service, due to a high risk of thermal shock. Peerless A offers wear resistance approaching H19, with slightly better toughness at high temperature (over about 600F). It may be used at tool temperatures up to 1100F, with brief exposures to 1200/1250F.
Typical Chemistry
Carbon 0.30%
Manganese 0.30%
Silicon 0.34%
Chromium 3.30%
Vanadium 0.25%
Tungsten 9.00%
Typical Applications
Dummy Blocks Extrusion Tooling
Forging Dies Hot Punches
Hot Upset Dies Hot Trim Dies
Permanent Molds
Hardening

Critical Temperature: 1520F.

Preheat: 1100/1250F, equalize, 1450/1500F, equalize.

High Heat: 2000/2250F, hold 2 to 10 minutes at temperature.

Quench: Air, salt, or interrupted oil to 125/150F.

Temper: 1000/1250F, hold one hour per inch of thickness (2 hours minimum). Air cool to room temperature. Temper twice.
Typical Properties
Oil quenched from temperatures indicated, double tempered as shown.
Tempering
Temperature °F
 Hardness HRC
(2050)
 (2150)
 (2250)
1000 49 51 53
1050 50 53 54
1100 49 52 53
1150 44 45 47
1200 37 41 44
1250 31 35 36
Air cooled from temperatures indicated, double tempered as shown.
Tempering
Temperature °F
 Hardness HRC
(2050)
 (2150)
 (2250)
1000 45 47 47
1050 49 51 51
1100 50 52 54
1150 45 47 49
1200 37 40 42
1250 30 32 34
Effect of Temperature on Toughness
Original RT
HRC
 Charpy V-Notch at (°F)
RT
 300
 500F 800
50 5 7 12 16
44 6 10 16 19
40 6 12 29 35
38 8 12 32 35
Surface Treatments
Because of its high tempering temperatures (>1000F), Peerless A may be treated by most surface treating processes, including conventional and ion nitriding, titanium nitriding, and other coatings or treatments. Nitrided surface hardness will be about 60/65 HRC.

Annealing
Heat to 1600/1650F. Hold 2 hours at temperature. Cool slowly (50F per hour maximum) to 1200F, then air cool to room temperature.
or
Heat to 1600/1650F. Hold 2 hours at temperature. Cool to 1450F. Hold 6 hours at temperature, then air cool to room temperature.

Typical annealed hardness: 207/241 BHN.

Stress Relieving
Annealed material: Heat uniformly to 1200/1250F, hold two hours at temperature, cool in still air to room temperature.

Hardened material: Heat uniformly to 25/50F below tempering temperature, hold two hours, cool in still air to room temperature.

Welding
Use H13 or other hot work tool steel filler material.

Annealed material: Preheat to 800/1000F. Maintain above 800F during welding. Reanneal, or temper 1450F 6 hours.

Hardened material: Preheat to 800/1000F. Maintain above 800 during welding. Allow to cool to hand warm (150F) after welding. Retemper at 25/50F below original tempering temperature (1000F minimum).

Physical Properties
Modulus of Elasticity ............................................................30 x 106 psi
Density ..................................................................................0.299 lbs/in3
Thermal Conductivity .............................200F ............15.5 BTU/hr/ft/°F
        ............................................................600F ...............17 BTU/hr/ft/°F
Thermal Expansion
        RT-200F ................................................................5.7 x 10-6 in/in/°F
        RT-400F ................................................................6.1 x 10-6 in/in/°F
        RT-800F ................................................................6.8 x 10-6 in/in/F
        RT-1200F ...............................................................7.3 x 10-6 in/in/F
        500F - 1200F .........................................................7.8 x 10-6 in/in/F
        800F - 1200F .........................................................8.1 x 10-6 in/in/F
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