My Observations: Very cloudy and splotchy etch on 1084. Possible bad heat treat?
Last night I heat treated a fairly thin (too thin) 2" wide 1084 blade with the following process:
1. Blade was forged, then normalized three times at reduced temps (by eye)
2. Profiled and beveled
3. Heat home built kiln to 1200 and hold for 20 minutes, then ramp to 1600
a. Insert blade, wait for temp to come back to 1600 and hold for 10 minutes.
b. Remove blade and cool in still air until black4. Ramp oven to 1499
a. Insert blade, wait for temp to come back to 1500 and hold for 10 minutes
b. Remove blade and cool in still air until black5. Reinsert blade into 1499 oven, allow to come to temp, and hold for 5 minutes
a. Remove blade and quench in P50 for 3 seconds, remove to inspect, then back in oil until cool (Blade was moved up and down to agitate oil)
b. I first noticed a very uneven color on the blade. Very cloudy, but i wasn't too concerned.6. Clean off oil, put blade between straightening jig during 425 temper. First temper was one hour, second temper was 2 hours
7. Grind blade to 400 grit, wash blade, and etch in FCL
a. After a quick etch I noticed that the areas that were previously hazy were still that way after etch (see 5b)
b. After a longer 5 minute etch I noticed more of the blade was turning dark but the spots were still there
This isn't the first time I've had this problem. It pretty much happens with every blade I heat treat and am wondering if it is common or if my process or even equipment is off somewhere.
Possible Solution: Should I raise the temp on my oven incase 1499 isn't really 1499? Should I let the blade soak longer?
The splotchy area is in the middle of the blade. It etches much lighter than the spine or edge. Does that mean that it didn't get as hard as the spine/edge?
Aside from the large lighter area after etch, there are also spots in the etch. It looks a bit freckled.
Any ideas or suggestions?
Here are 1000 words: