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Old 03-24-2021, 07:08 AM
John in WI John in WI is offline
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Default Pre and Post heating heavy steel

Hello folks,
First post here. Hoping to learn some things before starting a project.

I have some heavy "mystery metal" that I believe is some kind of low-carbon structural material. One piece is 3"x4", and about 2' long. To this I wanted to weld some more 3" thick material. I'm hoping to fabricate a post anvil for bladesmithing.

I joined a local maker's space that has a decent welding shop. I was probably going to go with SMAW (most familiar with it). I would use a band saw to deeply bevel the joints (especially on top where the impact would happen).

I know low-carbon is more forgiving with respect to weld cracking, but still, this thing will be built to literally take a beating.

My question is about pre and post heating (and interweld temperature). I was planning to use DC straight polarity (maximum penetration). Maybe using 6010 electrodes.

How hot should I get the pieces prior to welding? Is there a limit as to how hot I can get? Since I would be laying down numerous beads, the piece would get much hotter during the course or welding.

Finally, what about post-weld heating. Would it be enough to just let it air cool? Bury it in a bucket of perlite or vermiculite to slow the cooling down?

Thanks for any info. I'm asking about the actual fabrication of the piece. I'll get to the hardfacing part later.
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Old 03-24-2021, 09:17 AM
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milomilo milomilo is offline
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Welcome to the pile John. If it is mild steel no worries about heating or cooling. I would recommend 7018 electrodes.
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Old 03-24-2021, 10:02 AM
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Something that thick if mild steel I would use enough heat to warm it to the touch and no worry about post heat. Post a pic of the steel and welcome to the site!
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Old 03-24-2021, 10:05 AM
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digger doug digger doug is offline
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Why not doo some "chemical analysis" and then you'll know exactly what you have ?
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Old 03-24-2021, 10:21 AM
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If the material is truly a low carbon steel, I wouldn't bother with too much temperature control.

Just to make the welding easier, maybe 200-300 F preheat. 700 F maximum inter pass, and slow post cooling by burying in sand, kitty litter, or insulating blanket wrap.

I'd also think about skinning the work surface with a higher carbon steel to resist wear.

My preference would be multi pass 7018 fill and cap. Possibly 6010 root for maximum penetration. Also, interpass cleaning with a knotted wire wheel to remove flux, etc.

YMMV, my 0.02$ CDN.
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Old 03-24-2021, 10:23 AM
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Quote:
Originally Posted by digger doug View Post
Why not doo some "chemical analysis" and then you'll know exactly what you have ?
I'm curious what chemical analysis is available in a maker space or home shop environment at anything like a reasonable cost.
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Old 03-24-2021, 10:52 AM
BukitCase BukitCase is offline
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Got a grinder?

https://www.welding.org/wp-content/u...014/09/404.jpg

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Old 03-24-2021, 11:11 AM
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Quote:
Originally Posted by camdigger View Post
I'm curious what chemical analysis is available in a maker space or home shop environment at anything like a reasonable cost.
Ask the OP.....
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Old 03-24-2021, 12:15 PM
John in WI John in WI is offline
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Thanks for the info folks! I am not a great welder, but did study a bit of MIG at the tech college and messed around quite a bit with stick over the years.

I would love to do a legit chemical analysis on the material (believe it or not, I'm a chemist by training), but don't have any instruments for that sort of thing. It spark tests like steel (not iron). Also, the sparks don't seem nearly as brilliant as they do for a high carbon material. It was on a massive heap of flame cut steel drops. The only place in town that needs anything exotic is Oshkosh Corp--and steel armor plate doesn't end up in a recycling bin.

So I'm most certain it's some low-carbon stuff. I don't really care--it's heavy, and it's weldable.

I will get some photos when I get back to town, and put up some sketches of my plan. I was hoping to fabricate a legit London style anvil. I even have the steel drops for that (totalling nearly 400#). But for now, it's more than I need or can even move around.

For blade smithing, really a stake anvil is all you need. With the main member mounted vertically, most of the mass will be directly under the hammer. At over 100#, it will be great for smaller work.

Thanks again for the thoughts. I was hoping a little propane torch warmup would be enough. I don't know, bring it between 150-200F and start zapping it. I just wanted to make sure--it's purpose in live is to have the S(#*@ beaten out of it with a hammer.
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Old 03-24-2021, 02:06 PM
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greywynd greywynd is offline
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Bevel, warm it, 7018 and have at it.


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