Thread: Heat Treated Blade from Start to Finish or dud?

Hi Guys,

I'm quite new to blade grinding, so go easy :-)

About a year ago, a Blacksmith over here in 'Middle Earth' kindly forged me a razor blank. As I didn't have a belt grinder at the time, it sat in my workshop forgotten.

After my new grinder arrived and I did some practice on mild steel blanks, I decided to give the forged blade a go.

It took a really long time to hollow grind - I'm down to about 2mm at the edge now - I know why it took so long.

I re-read the email from a year ago and the blacksmith had hardened and tempered the blade before sending to me :-).

Questions - have I likely ruined the original heat treatment - I have been cooling and using my hand - dipping in water when too hot to handle?

Shall I continue to shape and then finish-grind, or should the blade be heat treated again. I suppose I could just try finishing, honing and shaving?

Any thoughts appreciated

My guess is that you have now destroyed the temper thus making it to soft to hold an edge for very long. However, you may luck out. It sounds like the edge thickness is still adequate for another heat treatment and tempering. Then you can finish grind but with a heck of a lot of care in keeping the blade cool.

Good luck

If you have kept it cool with no colouring of the blade it should be ok but
If it has blued it is toast and would need redoing

If at no stage it got hotter than about 200 -230 degrees C (yellowing on clean steel)
I'd continue keeping it cold enough to touch bare hand

You will want to keep the edge at about 1.5mm if HT is needed again

Otherwise either zero grind or get it down to at least 0.1mm (5 thou") or less to keep the bevel narrow

Hi Guys,

I've just had a thought.

Presumably it's just the tempering that would need re-doing once I get to 1.6mm (1/16 inch) at the edge?

Possible in a domestic oven, rather than sending back to the heat treaters?

Originally Posted by onotoman

Hi Guys,

I've just had a thought.

Presumably it's just the tempering that would need re-doing once I get to 1.6mm (1/16 inch) at the edge?

Possible in a domestic oven, rather than sending back to the heat treaters?

No, once it is over tempered from grinding you would need to re heat treat it. You can go down to 1mm prior to heat treating, and if you are going to re heat teat, I would do as much grinding as possible while you don't have to worry about over heating. Do you know what alloy of steel it is? It is possible that you did not over heat it if you never saw temper colors above straw.

Ah, OK, thanks bluesman7.

I believe that the steel is 01 Tool Steel, but I'll double check with the Blacksmith who made the blank.

If 01 Tool Steel - should HT be 780 to 800 degrees C (how long before quench?) to harden then temper at 230 degrees C for a time?

Also, what grinder speed is good for finish grinding (with least risk of overheating)?

Apologies for so many questions.

Originally Posted by bluesman7

No, once it is over tempered from grinding you would need to re heat treat it. You can go down to 1mm prior to heat treating, and if you are going to re heat teat, I would do as much grinding as possible while you don't have to worry about over heating. Do you know what alloy of steel it is?