forge welding mild steel issues

Will52100

Will52100

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Dec 4, 2001
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Having some issues with a hawk I just forged. Two hawks actually. One I did with some pretty cruddy wrought iron that I had to repair before even welding the bit in. The other I decided to try mild steel as WI is getting hard to find.

The one with wrought iron welded fine, and I used a chunk of O-1 for the bit, but after quenching the bit cracked down the middle of the O-1 piece. Hawk was normalized and cycled and annealed in my oven according to O-1 heat treat specs. Only thing I can think of is the O-1 is the culprit, I've done this with 5160 bits before with no issue.

The one with the mild steel is the real issue. I thought after forging that it was good, one of my best hawks so far, eye was nice and wide, proper taper to the blade, nice form, in other words well pleased with the shape and design. Well I used mild steel flat bar and preformed it, then folded and added a forge tapered piece of road grader blade for the cutting bit and it runs nearly to the eye. The road grader blade I forged the bit out of acts a lot like 1084, but really have no idea what it is, maybe a 1070 steel. Anyway while grinding the scale off after heat treat I noticed part of the edge had a flaw in it. So I decided to put a cheap handle in it and just use it around the place for testing and see how it works. I put the handle in and it was OK fit, but got to tightening it up with a hammer and it started to separate at the eye welds. Tapped some more and it split fairly easily and spread out. Looks like some of the mild steel welded, but other area's are dark and look like cold shuts. Now I didn't grind the surfaces before welding, possibly that would help. Hawk was cycled and heat treated in my oven, I used 1084 specs as a guess for the bit steel and it holds and edge and is tough.

Is there something in mild steel's alloy that doesn't like to bond to itself or high carbon steel? Or did I just need to be hotter? I've welded wrought iron together before with no issues like this.

Thanks
 

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You might have needed to be hotter or soak a little more at welding heat... that would be my first guess. I've done fine welding mild steel to itself in a gas forge but I do prefer coal for stuff like you are doing. Also, maybe you had to get to the anvil a little quicker? That's messed me up before, I know.

What are you quenching in?
 
Quench was Texaco type A heated to 150. Not ideal for 10xx steel, but did fully harden from file test. Also was an edge quench, about half the blade, way away from the eye end and file test showed it butter soft in that area. Possibly your rite and I needed to soak a little longer, but I also think I needed to grind it first.

One thing, I didn't do a lot of preform on the blade side first, it was thick with roughly a 3/8" thick bit, lot of widening and movement after welding.
 
Assorted comments:

Working mystery steel is always a crap shoot. The blade may be D-2 for all you know. I would be surprised if it was a simple alloy like 1070, and not something with considerable tougheners added.

I find that forging after the initial weld has to be done much hotter than you would for normal shaping. I start at welding heats, and do the main drawing and shaping. As the shape gets refined, I lower the temp a bit, but still work the hawk much hotter than I would a plain piece od 1080. Don't work it down into the lower reds...put it back and re-heat it.

With WI, you have to do nearly all the work at welding heat or it will come apart.

Soak time is very important with a wrap weld and drawing it out. The outer part may be yellow heat, but inside may be lower. Let the piece sit in the forge for a while to equalize before pulling and working the hot steel. ( Almost every bad weld on a hawk I have had came from not soaking long enough)

Many folks run the forge too hot. It should be enough to get the steel to 2200-2300°F, but it doesn't need to be so high that it will burn the steel if you aren't careful. You should be able to set the hawk in the forge and let it come to a full and even yellow heat without the edges sparking.

Go easy in the first few heats after the weld. You can shear the weld apart, especially if the two metals have very different hot hardness. (I suspect this is part of your problem).

After all the high heat work done on a mixed metal blade, it needs a thorough normalizing. Make sure the blade gets fully soaked in these steps, as you can leave the inside with coarse grain and only refine the outside if not careful. Cycle it down and then give it a long soak in the oven at 1200°F and let air cool. ( I suspect this is the other place your problem came from)
 
Pretty sure it's a simple 10xx steel, judging by the rust and spark and how a test piece responded to me playing with it, but without send some off now way to know for sure. Even if it is a 1075 it may have a little something else added to it that doesn't like to forge weld, but it doesn't have much if any chrome. It's a bolt on cutting edge for a road grader that was probably manufactured in the 60's. Doesn't have to be extremely tough as it's got a big low alloy blade supporting it, but again no idea without spec analysis.

I did all the shaping at welding heat like I normally do, may have let it get a little cooler than I should have, will pay more attention to that in the future. Also did full normalizations in the forge and then to the oven and multiple normalizations and annealing cycles, including 10 minuet soaks at reducing temps from 1550F down to 900F letting air cool out side oven between heats.

What gets me is that it didn't come apart while drifting as I was getting down on it pretty hard while doing the final shaping. It split while beating a wood handle in and "pop".

Anyway, going to cut the eye end and peel the split weld open and see just what welded and what didn't.

Also going to fire the forge up and try another, this time with my tried and true chunk of 5160 for a bit.

Thanks
 
Mild steel is full of junk! Get some 1018/1020 for the body of the hawk, or stick with wrought iron.

01 is a problematic when forge welded. Use a simpler carbon steel, W1,W2,1095,1084, etc.
 
Will, You are right that you need to clean the steel before forge welding. When welding mild to high carbon steel, keep in mind that the mild steel welds at a higher temperature than does carbon steel... so what I do is pre-heat the mild steel to dark cherry red before inserting the carbon steel bit.... so this way each steel reaches its welding temp at about the same time

Another issue you may be experiencing is that road grader may have some chrome content and if that is the case the welding process is different. When using "mystery steel" try a few little test pieces first and test how strong is your weld.

hope that helps
- Joe
www.szilaski.com
 
Now if I can just find some 1018 locally. I was thinking I may have an issue with the mild steel bar stock, like you said, no idea what's in it. I do have some wrought iron left and just ordered some more so I'll probably stick with it. Want the eye and body to be soft anyway.

Would love to send a piece of the grader blade off for analysis, pretty sure it doesn't have much if any chrome in it, but don't really know except it's got plenty of carbon. I have forge welded 5160 and 52100 with no issues, but that's about as high a chrome content as I've went forge welding.

Pretty sure using the O-1 in the wrought iron was the wrong thing to do and over heated it while welding and that caused the cracks. Oh well, can always use another beater to carry in the mule.
 
All of the grader blades we have through our public works department and my family's construction business are abrasion resistant grades of steel. There is only one company I know of that they get 10xx steel blades and teeth from. Can't remember the name of the supplier off the top of my head though. I went fishing in the same holes when I started fabricating stuff and making knives/tools.

I have a fairly big stockpile of blades that are AR-500 off their big graders. Been making shooting gongs with them for a few years... That stuff is beyond tough. 1/2" plates will take non-a/p .338 Lapua rounds at least at distance...
 
Good deal on the Ar500 plate, all my targets are made from it, but most of mine are only 3/8" thick. They will stop anything I have, up to 30-06 FMJ with no issue. Though steel cored 7.62x54R will leave small dimples. And a buddy's 300 winmag with molly coated bullets punched a hole in one like it was drilled.

Just looked up the alloy for AR500, and it list .27 carbon and 1.0 chrome. The grader blade I got has more carbon, it sparks the same as a piece of 1084 I've got, and when quenched and broken has a nice silky fine grain. If it was a bigger piece I might worry with having it analyzed. Any way I'm pretty sure it's not an AR steel. Though I've got some left over pieces of AR500, wonder how they'd mix in with some damascus?
 
Ive welded up, well more mild steel hawks than I could ever remember..One thing Ive learned is that it needs to be clean and hot..Much hotter than welding high carbon steels. Personally I prefer it to be high yellow bordering on buttery white to weld "right"..
 
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