HALCOMB® 425
(AISI H19)
Halcomb 425 is designed for higher operating temperatures than H13, where wear resistance and heat check resistance are more critical than toughness. While H19 has excellent heat checking resistance, drastic cooling (flooding, dunking) should be avoided due to the risk of thermal shock. Halcomb 425 may be used for tool temperatures up to about 1100F, with brief exposures up to about 1200/1250F.
Typical Chemistry
Carbon 0.40%
Manganese 0.40%
Silicon 0.40%
Chromium 4.25%
Molybdenum 0.40%
Vanadium 2.10%
Tungsten 4.20%
Cobalt 4.20%
Typical Applications
Forging Dies Hot Punches
Hot Upset Dies Die Inserts
Extrusion Tooling
Hardening

Critical Temperature: 1540F

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

High Heat: 2100/2200F, 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
(2100)
 (2200)
1000 56-57 58-59
1050 54-55 56-57
1100 51-52 53-54
1150 49-50 51-52
1200 45-46 46-47
1250 39-40 40-41
Effect of Temperature on Impact Properties
(Oil quenched from 2150F, double tempered to original hardness indicated, tested at elevated temperature as shown)
Original RT
HRC
 Charpy V-Notch at (°F)
RT
 300
 500
 800
 1000
48-50 6 12 13 14 15
44-46 11 13 17 19 19
38-40 11 18 23 27 30
Surface Treatments
Because of its high tempering temperatures (>1000F), Halcomb 425 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 1400F. 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 700F during welding. Reanneal, or temper 1400F 6 hours.

Hardened material: Preheat to 800/1000F. Maintain above 700F 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 psi x 106
Density ..................................................................................0.288 lbs/in3
Thermal Conductivity .............................200F ............15.5 BTU/hr/ft/°F
        ............................................................600F ...............17 BTU/hr/ft/°F
Thermal Expansion
        RT - 400F ..............................................................6.1 x 10-6 in/in/°F
        RT - 800F ..............................................................6.7 x 10-6 in/in/°F
        RT - 1200F ............................................................7.2 x 10-6 in/in/°F
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