Accidentally overtempeted blade....

[Hermanelldena]

So I had heat treated a knife of 1095, and when I was gonna grind down the bevels all the way, I kinda just forgot that I already had heat treated, and I overtempered one part of the blade to a purple temper. What would you do? Should i quench again? Leave it as is?

 

[Stacy E. Apelt - Bladesmith]

I believe you mean "overheated one part".

I would put a sharp edge on the blade and test the area with a brass rod or wooden dowel test. If the edge rolls, then dull the edge back and re-do the HT.

While terrifying to see happen, a small blue area may not be as damaging as it seems.

 

[mete]

Temper colors are surface oxides How long was it at the temperature .? Sometimes you can sharpen the blade a few times to get past the over heated area.

 

[Hermanelldena]

Temper colors are surface oxides How long was it at the temperature .? Sometimes you can sharpen the blade a few times to get past the over heated area.

Just for a few seconds I belive. I have a lot of material to remove on the edge, but I belive it may have penetrated

 

[joedhiggins]

Follow Stacy's advise. Tempering is a process that requires both temperature and time. Assuming you nailed your heat treat, and my color purple is the same as yours, a 520F temperature, held through time, would reduce the hardness of that area to 59 or 60 HRC. In this case, your duration at temperature was almost assuredly measured in time less than a second as the surrounding steel pulls heat away incredibly rapidly. For that length of time, I would guess that that small area maybe lost a point or two of hardness at most. TME is also not an issue as it requires time durations measured in minutes to be measurable.

Best practice is to avoid such local heating, but practically, I doubt anything measurably negative happened to the blade here.