Re-heat-treating A2 - can I simply repeat the process ?

Heat treated some 1/2 thick, 1" wide, 2" long pieces of A2 and did not get the hardness I needed (preheat emtpty oven to 1450, drop in the steel, wrapped in air-tight in SS foil bags with some brown paper in the bags, held @ 1750 for 25 mins). When treating 1/8 thick pieces the results were spot on .

For the thicker pieces I got somewhere around 50RC - was hoping for near 60RC. Thinner ones are just right.

Can I repeat the heat-treating cycle for the softer pieces, by simply redoing the process ? I think I didn't give enough soak time, should go to may be 40 minutes ???

I cooled them down by taking the bags outta oven and laying them onto firebricks in front of a rathear weak fan, turning bags over once in a while.

Reply to
rashid111
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You're probably short on hold time. In general, a 1/2"-thick piece takes 30 minutes just to reach temperature in an air-atmosphere furnace. Then the recommended hold time, after reaching temperature, ranges from a minimum of

25 minutes (Uddeholm) to around 45 minutes (Crucible).

Here's a Crucible heat-treatment data sheet that should help:

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A2 should be double-tempered, especially if you're doing an interrupted quench (quench interrupted at 120 - 160 deg. F). It should be double-tempered even if you aren't doing an interrupted quench. It takes two tempers to temper martensite converted during the first temper. This applies to all alloy tool steels, for best performance. Just temper it the same way, twice.

I don't think that A2 has to be re-annealed before re-hardening. HSS does. I've not seen any reference for A2 that says it's required.

BTW, with 1/2"-thick sections, you may want to ramp up the temperature more slowly, for safety. See the Crucible data sheet for more info. Also, you should look up the Uddeholm data sheet for heat-treating A2. I think it's online.

-- Ed Huntress

Reply to
Ed Huntress

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