Bad heat treat?

Rick Otts

Rick Otts

Well-Known Member
I HTed my 1st blade 1084 1450 for 4 min.I then tempered at 350 2 times.Now when I run a file across it it leaves a line wat should I do retemper?
 
when you say leaves a line, does that mean the file bit into the metal or just scratched a bright spot where it ran across it?
A shiney line is OK, shavings or metal removed means soft.
 
Also keep in mind.....a file test doesn't mean a whole lot AFTER tempering. (I'm not sure it means a WHOLE lot prior to tempering :p ).

A good file will likely bite into a hardened AND tempered blade.
 
Good question. I’ve done it immediately after cooling and days later. I can’t tell the difference.
 
Generally speaking.....I believe its best to temper as soon as is reasonable to reduce the stresses induced from quenching and the conversion to martensite.

If I'm not mistaken, it would be important to allow all martensite to convert before tempering but once that's done, I don't see any reason to delay tempering.
 
I have always tempered after hardening espically for forged blades. I have read in my studies that a hardened blade can crack later due to stress if not tempered immediately. I would think this is a bigger problem in forging blades because we introduce stress into the steel during forging though there are ways to reduce stress prior to hardening. All of that being said I do not study metallurgy I am more of a practitioner I learn from watching,doing and reading. I am. Sure a metalurgist will be along shortly to correct or expand.
 
John's right. You can loose blades if you set them aside after quenching and go ahead and normalize and quench others in a batch. Have your oven pre-heated and ready to go before you go out to heat treat. He is also right that you have to let your blades cool to touch before you stick them into the waiting oven or the unconverted austenite can convert to bainite.

Personally, I would not do a 4 minute soak before quenching. I'd just wait until the last of the shadow from decalesance passes from the blade the get it right into the quenchant. I think that 350° is a little low for 1084. I would go up to 400°. Try working with that blade and see if you have any chipping out. You might even try driving it through a thin brass rod to see what happens. After working the heck out of the blade you might even want to do the unthinkable and break the blade to check on the grain size.

Doug
 
J. Doyle said:
Generally speaking.....I believe its best to temper as soon as is reasonable to reduce the stresses induced from quenching and the conversion to martensite.

If I'm not mistaken, it would be important to allow all martensite to convert before tempering but once that's done, I don't see any reason to delay tempering.
Click to expand...

This is what I have always heard?
 
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