damascus won't temper correctly

G

Groucho

Member
Good evening,
I made a 4 damascus blades using Alto's steel 1084 and 15n20. I forged welded them, ground it to shape and welded a piece of 1084 to each for the tang. I harden them to 1500 degrees soaked for 10 mins, and cooled it down in hydraulic fluid quickly. I tested the hardness it varied from 76 RC to 81 RC. I tempered them twice at 425 for 2 hrs. then air cooled to room temp. tested them and they read 78 to 75 RC. so I soaked again at 500 and soaked for 2 hrs. and cooled till room temp.with no change. I want to get them down to about 58 to 59 RC. What am I doing wrong? There is even a RC swing from one side of the blade to the other side. Hope somebody can help me out. Thanks
 
Based on the numbers (76-81Rc) I would suspect that something is out of calibration with your tester. I've never seen a piece of 1084 or 15N20 that tested out to a 76 Rc.... even in its "as quenched" state. Even if water quenched, the hardest I've ever seen a piece of 1084 achieve is in the mid 60s.
 
What exactly are you using to check your hardness ?? Numbers are 10 points to high . Do you have any test blocks to determine if your hardness tester is accurate ?
 
What these two gentlemen above are saying very politely is that it is physically impossible for those steels to reach those Rockwell C scale numbers. Maybe the A scale is what you are reading....but it certainly is not the C scale, unless your tester is way out of wack. You might want to consider ditching ATF fluid as a quenchant, too. If you don't have access to quench oils.....do yourself a huge favor and use canola oil warmed to 130F.
 
There are a few red flags to me too but I'll save that for later when we have more info. But you maybe testing on some spots that have some fire scale if you didn't grind them down to clean bright steel before testing.
 
John brings up some thoughts.... I was assuming that the steel was "clean" and flat? If there is scale on the steel, or its even slightly out of level/flat, it will affect the readings.....but in my experience its generally the other direction from the Rc numbers you indicated.
 
Well you guys were right, it was my tester or should I say the one using the tester. I forgot to do the last procedure to get a reading, release the load. The tester is reading with the test bar and the blades are reading in the high 20s. Does that sound right with what they have gone thru? Will one side test of the blade differently than the other? Again thanks, I can let go of my hair.
 
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