Thread: How hot to retemper steel?

I have a blade here that has some rainbow streaks on it, presumably from getting too hot on a buffer. I've been curious about taking a blade like this, getting it hot and oil dipping it... That would be the process to re-temper, correct?

How hot would I need to get the metal? I currently have the means to get it to somewhere between 750 and 800 degrees farenheit with very even heat. I'm sure I can heat it beyond that, but not nearly as evenly.

How hot do I need to get this thing?

Originally Posted by HNSB

I have a blade here that has some rainbow streaks on it, presumably from getting too hot on a buffer.

I don't have the expertise to answer your question but if it was my blade I would post a photo for the experts to check out the rainbow streaks. Might be something else. I've seen lather left on a blade produce what resembles over heated steel.

Good call Jimmy. Whatever it was buffed off.

I'd still like to hear from the experts, for future reference.

probably not explicitly possible. edge will burn up, then there's scale. Assuming your piece survives heat treat it will need regrinding so it will be a fair amount smaller .

just so you know; you are still waiting to hear from an expert

different steels need different heat treatment to temper.
What type of steel do you have?I know that Hitachi steels are heat treated in the 700-800 C range, then quenched in Oil/Water.
The process requires precise temperature control or you will not achieve the required results.

How would a person know what type of steel the razor is made out of?
I would have the ability to control the temperature to within about 5-10 degrees F.

Maybe this is something that is just not possible for the amateur?

Originally Posted by HNSB

How would a person know what type of steel the razor is made out of?
I would have the ability to control the temperature to within about 5-10 degrees F.

Maybe this is something that is just not possible for the amateur?

Not sure about the steel, but if you have to go to 700C that is 1290 F, you need a special furnace for that.

Mike Blue or Butch Harner could certainly tell you. Maybe shoot one or both a PM in case they haven't seen the thread.

You don't know the steel, so it is a guess work quench/ heat treat. Best hope is for simple high carbon tool steel

Really you are not re-tempering. the temper is gone when overheated. Which is done somewhere 250F to 500F (I guess) many home HT get tempered in home oven.

First thing is back to zero, so you'd want to anneal it at least once- heated to non-magnetic and allowed to cool slowly. Then you need heat it again to quench. Water- ouch it'll break. Used motor oil etc are not quench oils so that is another variable. This is not a big Scottish dirk or bowie knife the thin material really adds to the un-doable by novice side of the scale

But when you get done, you'd be set to make another

it'll be hard, because the scale and warping that comes with something as thin as a razor. you can do it if it's a wedge razor though. heat to 1500F soak 5 min, interrupted quench in water, temper at 350F.