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#1
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What happen here??
Ok I'm cruising along, I heat treated this 1084 all went well (mini forge) tempered @400 2X
I sand blasted with fine black diamond and I have these shiny spots like the media couldn't cut into it. I was going to go with the blasted look, now I guess Ill have to sand this out. Arrrrr What Happen??? |
#2
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That is most excellent workmanship. My only guess is overheating, and that is just a WAG. Where did you get this batch of steel? I've seen similar problems like this on a couple of other boards lately, and the answer seems to point at a bad pour of 1084 from a particular source.
Last edited by WBE; 05-28-2013 at 12:56 PM. |
#3
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I went to one of the boards, and the problem was with W-2, but looks pretty similar to what you have.
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#4
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WBE thanks, Aldo's 1084 1/4 thick. I'm going to sand it out if I can Friday I just want to know what the deal was here. It may have been slightly over heated.
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#5
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I'm going to go with over heating too. I had a similar issue with some 1084 that I know for a fact that I over heated a little. I didn't sand blast it but when I etched it in ferric chloride pretty much that same pattern came out. I ended up busting that knife into pieces just to see the grain and sure enough it was large in some areas and medium in others.
Great job on that blade! Your lines are very sharp. __________________ J, Saccucci Knives, JSK |
#6
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Another thought... Was the blade completely sanded and clean before blasting? If you had any scale or any inconsistencies in the finish prior to blast and can transfer, I know I've seen similar things happen. If this was the case, sanding to a uniform finish then blasting should fix the issue. If not, then I have no idea.
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#7
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I'm not sure about the cause either but maybe I can work on the finish. Any time you plan to use a fine media for blasting you need to be especially sure you have a fine finish on the blade before you start. Even with a coarse blasting media you need to have a scratch free clean finish. So, on this blade, you might try switching to a coarse media or raising the pressure with the one you have or both...
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#8
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Ok the problem might be two fold then. I used the sand blast to clean the scale off with 90lbs psi I was seeing sparks. 2nd I may have been too hot (by a little) for the HT
Ray I tried to boost the PSI and stay on the shiny spot, it did nothing. I hate to sand it and change the look but.... Thanks for the advice, all. |
#9
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90 psi should be more than enough pressure and quite a bit more than would normally be used with a fine media. Even with a coarse media I wouldn't go higher than about 60 psi if I was trying to create a finish, for fine media about 40 psi is a good starting place. The fine media is too soft, high pressure just breaks it down to powder. For fine to work for finishing you should have a very nice finish already on the blade, maybe even mirror polish.
All that being as it may be, it is very possible that high pressure and coarse media still won't hide all of that spot very well but if it was convenient to try that's what I'd do. If that turned out to be the case then I'm doubtful that sanding it will change it much either unless you can remove some steel and then only if that spot is on the surface and doesn't go too deep ... |
#10
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I'm going to grind it out see where it goes. Thanks
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#11
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Used some 400 grit to uncover this, almost looks uniform.
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#12
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looks like decarborization to me, I'm no pro so I'm just taking an educated guess, but that's what I'm assuming, too hot for too long. If this is the case you should be able to salvage it by grinding it out, but then I would consider re-heat treating it.
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#13
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OOOH!,Are you sure you dont want to leave that?I think it looks cool!
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#14
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And,yes,it does look like decarburization,but its still cool.
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#15
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Got her too hot.
Need to normalize a couple of times and re-HT with careful attention to temps. Looks cool - yes, just overcooked the steel. __________________ Carl Rechsteiner, Bladesmith Georgia Custom Knifemakers Guild, Charter Member Knifemakers Guild, voting member Registered Master Artist - GA Council for the Arts C Rex Custom Knives Blade Show Table 6-H |
Tags |
1084, advice, art, back, bee, blade, blades, diamond, forge, grinding, heat, hot, knife, mirror, pattern, polish, powder, sand, scratch, sharp, steel, surface |
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