More 1084 weirdness

JTknives said:
ok, then riddle me this?
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Ok folks, (sorry, but this is how i think about root cause on things like this) ... JTs question is a valid one. The question of “hot spots” in the oven would be mitigated by the thermal properties of the steel (thermal conductivity and heat capacity). Especially higher conductivity will “spread” the heat and mitigate hot spots. A quick search of other alloys has 1075 almost identical to 1084 in both properties, and O1 actually quite a bit LESS in conductivity than 1084. JT - since you have not mentioned it, i assume you have not seen this problem with O1? If not, then in my view this points yet again to the material, not the oven...

sure you do not want me to try to get an location-dependent elemental analysis via ESCA? It is non destructive.
 
Cushing H. said:
Ok folks, (sorry, but this is how i think about root cause on things like this) ... JTs question is a valid one. The question of “hot spots” in the oven would be mitigated by the thermal properties of the steel (thermal conductivity and heat capacity). Especially higher conductivity will “spread” the heat and mitigate hot spots. A quick search of other alloys has 1075 almost identical to 1084 in both properties, and O1 actually quite a bit LESS in conductivity than 1084. JT - since you have not mentioned it, i assume you have not seen this problem with O1? If not, then in my view this points yet again to the material, not the oven...

sure you do not want me to try to get an location-dependent elemental analysis via ESCA? It is non destructive.
Click to expand...

If you could that would be amazing.
 
I had my wife snag a thickness measurement. I removed just to clean up on the back side and the rest from the test side. So I would say I removed a solid .020 from the polished side.

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Re: ESCA on weird HT blade:
JTknives said:
If you could that would be amazing.
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Could you give the dimensions of the blade (length and width)? I will reach out to my contact and see if 1) she can do the scan, and 2) if the thing will fit in the vacuum chamber. I have used this chamber myself quite a bit, but dont remember the actual dimensions...

If we need to do so to get it to fit, can we cut a section of the blade to a smaller length? (sorry ... that WOULD be destructive :-) )
 
Willie71 said:
I have two thermocouples from auberins and placed them in different places in the oven at different temperatures.
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I still don t understand , you put complete thermocouples inside oven or you drill hole in wall ? I have no idea how to do that .........
 
JTknives said:
ok, then riddle me this?

How come just these blades? The number of blades that go through that oven is rather impressive. All the blades we heat treat are hardness tested and only these have done this? Like I said I have had this problem before and it was the EXZACT same material (alloy) from the same claimed source. It was from the beginning of the year if I remember correctly. And thy showed up during surface grinding. I will do some digging and see if I can find the data on that. We have had a handful of other heat treat failures but that was due to customers buying on eBay from a seller that was known to ship mild steel. We just did a batch of 1075 that I cut out from a sheet supplied by AKS and thy hardened beautifully.

Just did a quick search and found an email dated 2-28-18 from a customer that bought 1084 and could not get it to harden. Says he was getting upper 40s Rockwell.
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I don't think being close to the coils or rack uprights is what happened to your blades, I just think what Natlek suggest is possible, if someone placed a blade very close to the elements. In this case, it seems fairly conclusive that the steel is bad.*


*cursed or haunted
 
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DevinT said:
I remember you saying that you can’t do quality heat treating in a small furnace.
Hoss
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You remember wrong or you do not understand what I was saying then. Evenheat oven are not good for testing samples of steel in very close different temperature , say one sample on 1450 and next one on 1460F..... and then make test of toughness hardness...etc .
My new/old oven should have good heat uniformity inside I hope , HT elements are wound around muffle ...But we are here deep of topic with this ...........
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Cushing H. said:
Ok folks, (sorry, but this is how i think about root cause on things like this) ... JTs question is a valid one. The question of “hot spots” in the oven would be mitigated by the thermal properties of the steel (thermal conductivity and heat capacity). Especially higher conductivity will “spread” the heat and mitigate hot spots. A quick search of other alloys has 1075 almost identical to 1084 in both properties, and O1 actually quite a bit LESS in conductivity than 1084. JT - since you have not mentioned it, i assume you have not seen this problem with O1? If not, then in my view this points yet again to the material, not the oven...

sure you do not want me to try to get an location-dependent elemental analysis via ESCA? It is non destructive.
Click to expand...


The steel may not be able to spread the heat evenly if it's very close to a heating source, be it an electric element or a jet in a gas forge, and especially if the blade is thin. I mean really close. Again, not saying that's what happened here, just saying it's possible to happen.

I'm just gonna call it now: an elemental analysis is going to reveal that an inconsistent melt was rolled. BOOM! Ask the welder/fabricators about Chinese remelt/Ebay steel, and finding half-melted ball bearings and crap in the bars when they're cut. o_O
 
I agree with Natlek. The subject has drifted.

Suffice to say that the situation is an MRE .... a mystery wrapped in a riddle, wrapped in an enigma. Unless there is a bar of identical unworked steel from the same bars/batch, we may never know what the issue is exactly.

Each company/person in the chain from making the steel to hardening the knife will defend itself with fingers pointed at the others.
The foundry will say the steel was fine, and something went wrong after they poured the ingot. The mill will say it was either the foundry, the user/seller getting some other steel mixed up, or the HTer doing something wrong. The user/seller will say it was the foundry, mill, or the HTer.
The HTer will say it was the mill, mixed up or junk steel, or the foundry.

The argument will go nowhere unless we can get a significant length of the same steel in an unworked condition. Does anyone have a full length bar of the steel.
 
Stacy E. Apelt - Bladesmith said:
ach company/person in the chain from making the steel to hardening the knife will defend itself with fingers pointed at the others.
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Stacy - really??? I just can not imagine anyone in the chain not saying "yeah - it might be my fault..." :-) (yes - I say that very much tongue in cheek - Stacy is absolutely right). the question is: how do we identify "a bar of the (same) steel" without processing it to identify a defect??
 
"I just can't imagine anyone in the chain not saying "yeah - it might be my fault..."

Short of one of the makers who had JT do their HT having more of the same bar, or a supplier who has good records offering some bars of the same batch for testing, I don't know where we will get good data on this situation.

You know, it hasn't been all that long ago when steel sellers cared about the small folks like us. I bought 40 feet of steel from Admiral about 25 years ago. I got a phone call after a couple months and they said the steel was labeled wrong. They had sent 5160 instead of 1075. They said they had already shipped replacement steel and for me to keep the 5160. I think I still have some of it today.
 
In my career i did a LOT of root cause analysis. Frankly, much of what that required was smoothing ruffled feathers, and assuring people we were not pointing fingers, but rather as a team trying to understand what was going on. Most of the time (90% or more) what people initially assumed what was going on was wrong. Data always wins the day (it is much more neutral tha an “i think” statement. ). Getting an elemental analysis may or may not yield anything definitive ... but if it does, we are a step ahead. Again, data is power (and is a less threatening influence over the supply chain)
 
Cushing H. said:
In my career i did a LOT of root cause analysis. Frankly, much of what that required was smoothing ruffled feathers, and assuring people we were not pointing fingers, but rather as a team trying to understand what was going on. Most of the time (90% or more) what people initially assumed what was going on was wrong. Data always wins the day (it is much more neutral tha an “i think” statement. ). Getting an elemental analysis may or may not yield anything definitive ... but if it does, we are a step ahead. Again, data is power (and is a less threatening influence over the supply chain)
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I am all for this 100%, like I said early on I’m not pointing fingers. I honestly want to figure out what’s going on. If it’s me then I want to know. But on the other hand I don't want to bend over and take one for the team so to speak. I honestly want to provide the best heat treating service I can to my customers. This involves being honest with ones self first and for most. I honestly do not think it is anything I have done but god forbid if it is then I sure as hell want to know about it. I have always had respect for people and company’s that stand up and own there issues and I’m trying to fallow in there footsteps. No one is perfect and I don’t think the majority of us expect others to be. But that does not mean we cant strive for perfection. Remember what we want is on the other side of hard.
 
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