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I Forge Iron

tempering H 13

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H13 air hardens in small sections. I usually forge to shape then put the tool in the gas forge and turn it off. This isn't a full anneal but is a good stab at normalizing. I then bring back up to an orange and let air cool. This will yield somewhere around 46-50 Rc.

You can typically water cool chisel edges with no ill effects - it's a great steel for hot work. S1 is works well due to the tungsten content but is hard to find in most places; S7 is also good but has more of a tendency to hot check. I use H13 almost exclusively for my hot tools.

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This alloy is one of the Hot Work, Chromium type tool steels. It also contains molybdenum and vanadium as strengthening agents. The chromium content assists this alloy to resist softening if used at higher temperatures.

Machinability of H13 is medium to good. It rates as 75% that of the W group water hardening tool steels which are low alloy and of generally good machinability.

Heat Treatment Preheat to 1500 f and then heat to 1850 F. Hold at 1850 f for 15 to 40 minutes and then air cool (air quench).

Forge at 1975 F down to 1700 F. Do not forge below 1650 F.

Anneal at 1600 F followed by slow furnace cooling at a maximum of 40 F per hour.

Temper at 1000 F to 1200 F for Rockwell C of 53 to 38. It is advisable to do a double temper by repeating the process and use 1 hour at temperature each time.

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Hi if you do not have the tools to properly aneal as discribed you can heat to nonmagnetic (not much beyond) and cool however slowest you can and it will be somewhat soft as it wants to get to 1850 F to harden. The idea is to heat past tempering temp. but below hardening temp. It would be better of course to properly aneal the steel but without a heat treating oven might be impractical.

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I've had occasional success annealing air hard steel without a computer controlled kiln. I heated two large steel blocks in the forge along with the tool steel. Get everything to temperature, remove from forge and quickly clamp the tool steel in between the two large hot blocks. Bury the whole mess in vermiculite, and leave alone for a couple days. Sometimes it works, sometimes it doesn't.

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