Heat treat/metallurgy question

D

ddm4elite3442

Joined
Mar 16, 2017
Messages
9
So, I was heat treating a 1084 blade in my gas forge with thermalcouple. When one of my kids plowed into the side of my shop with the gokart. I layed my blade down in the forge to go check on my kid, but when I got back, the temp reading was close to 1,650 degrees F. I quenched it an’ ground off the scale and it was plenty hard as my file skated across it. So my question is this, is there anything going on that would degrade the quality of the steel by heating up past the suggested HT temp on 1084 like that ? Or is the steel still good, but with just more scale build up due to over heating ?
 
The steel is probably fine, but your HT is less than nominal.
I'd re-do it.
 
Thanks for the response’s, sounds like I best just re-HT. Can anyone tell me what goes on with the grain structure for 1084 if taken over the HT temp of 1,450/1,480 or any high carbon steel ? What’s going on that brings the quality of the steel down, what effects does it have for a finished blade if it’s over heated but comes out with a 64/65 HRC, and then tempered to a 60 HRC... will it not hold an edge, does it lose its strength n durability ? I’m really curious, cause well, I’m just not knowledgeable in this area.
 
I'm kinda curious too. I've always understood that grain growth occurs and it is combination of two factors...time and temperature. So what happens if the temperature was a little higher than optimal, but there was no real time involved...like less than a few minutes or so. Will temperature alone cause grain growth, or can it occur in as little time as 2 or 3 minutes?
 
Temperature is a much stronger factor than time with grain growth. Larrin is better at explaining why large grain reduces the steel's toughness, so I'll just say it does, and quite significantly. Poor toughness leads to poor edge stability, so also poor edge holding. So, like others said, just redo the HT.
 
I would re do it completely. Normalize it again at 1650f but just air cool. A quenched blade at 1650f possibly has stresses that may complicate the hardening at the correct temp (I don’t know for sure...better safe than sorry)

Then cycle 2-3 times at ~1500f air cool

Then harden at ~1500f, quench.
 
You must log in or register to reply here.
Back
Top