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I have a question about heat treating O1 tool steel. In this process the tool is heated, then quenched in oil, meaning the hot tool is plunged into a bath of oil that is normally preheated to about 200 °F. The tool is then transferred to a tempering furnace where it is held at the tempering temperature for a period of time. This transfer is supposed to happen immediately after the quenching has been accomplished.

The problem is that after I quench the tool, it is covered in oil (obviously). If I put the tool into the tempering furnace with oil on it, it can damage the furnace because the oil can be converted to fumes which can contaminate the heating elements in the furnace.

However, if I try to clean the oil off, I have a problem that I am trying to clean a hot object and as I do so, then the tool is cooling down. If it cools below about 150 °F, then I think the heat treatment will be imperfect because in the case of O1 from what I understand you are never supposed to let it get below that temperature during the process.

So, the problem is: How can I get the oil off of the tool without cooling it?

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    It seems odd that a tempering furnace designed for a process that involves first plunging the steel into an oil bath would be damaged by the oil fumes. Does the furnace manufacturer state that there shouldn't be oil on what you put in it? If so, do they offer any advice on the process? A few thoughts: you could at least blow off excess oil using a heat gun with a nozzle to concentrate the air, or perhaps wipe the item on fiberglass cloth. Neither would cool it, but also wouldn't eliminate all traces of oil. (cont'd)
    – fixer1234
    Jul 22 at 3:42
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    Can you put the item back in whatever you used to heat it before the oil bath or hit it with a blow torch just long enough to burn off residual oil, then put it in the tempering furnace?
    – fixer1234
    Jul 22 at 3:42
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    What's the tempering temperature? Is it below 200? If so, why would the oil turn into fumes at a temperature that low?
    – Catija
    Jul 22 at 6:30
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Industry always degreases quenched steels before going into the tempering furnace. It is good practice to temper as soon as possible after quenching. I cracked some O-1 parts once, but you could see some cracks as they came out of the hot quench oil. Looking at TTT curves for a similar alloy ( no curve for O-1); martensite starts forming at about 400 F and is mostly finished by 250 F. That is, if it is going to crack it will likely crack by 250 F . So cooling to room temperature to degrease is not likely to cause a problem.

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