Should I re-do my backyard heat treat?

L

leozinho

Joined
Jan 7, 2005
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I used a paint can forge to harden four blades made from Aldo's 1084. I did them individually. I tested with a magnet until the blade lost it's magneticism. I put them in the back in the forge for another minute or two, thinking they should have reached the target point. (1450 degrees.?) I didn't want to overheat the blades. I quenched in 120 degree canola oil. One blade created a flame. The other three did not.

Quench oil was near my forge, and I didn't dally between taking out of the forge and submerging.

I tried the skate a file technique to measure hardness, and felt the file didn't skate like I was expecting. I wanted to chalk it up to decarb. I went ahead and tempered at 400 degrees for two hours, twice.

Now I'm looking at them more closely, have sanded off the decarb and I'm testing with a file and comparing it with some non-heat treated 1084. I'm second guessing my heat treat. They seem harder than the non-heat treated steel, but not that harder. The file left a few big gouges, and I don't think I was bearing down hard. Also, it might be my imagination, but the blade that flamed in the quench does seem a little harder than the rest. (Presumably, I heated that blade more than the others, since it flamed. But there may be other variables I'm not accounting for.)

What say you? Re-do the heat treat giving them more time in the forge after losing magneticism and worry less about overheating?

I'm thinking about leaving one as-is for the heat treatment, grinding it down to final profile and put an edge on it and testing the crap out of it and comparing it to the others (that will get re-heat treated.)
 
Blind leading the blind, but here are some thoughts.

1450 may not be enough, and 1-2 mins past non-magnetic may not even get that hot. In the recipes I use, 1500 is the target for 1084. 1414F, non-mag is red to me. I wait for it to be bright red (almost orange) before I quench. I sometimes use a 1475F and 1500F tempilstik (when I can find them).

how much quench oil are you using? remember, it gets hotter each time you use it, so it may not be cooling the steel as fast as you want after the first blade or two. More quench has more volume to disperse heat.

as for a test blade, worth every penny of steel and hours of grinding IMO.
 
Ideally, your target temp should be around 1500° with 1084. Higher carbon blades are best at 1450° to 1475°. Go about two shades of red higher in heat than the non-magnetic for the lesser carbon simple steels. For the average blade, you need at least two gallons of quench.
 
Thanks guys. All indicators are pointing to not getting the steel hot enough. (I had a thermometer in the quench oil. I was going slow between these blades and even put the pot back on the grill to reheat the quench. It was 120. I don't think that was the issue.)

Anything wrong with re-doing the heat treat? Seems like I've read that you can try again.
 
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