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Welders and Welding Which welder is best and the best way's to use them.


Welders and Welding Which welder is best and the best way's to use them.

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  #1  
Old 06-17-2016, 03:01 PM
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Filler for 4130

I have a buddy that wants me to build some bicycle handlebars. He insists on heat treated 4130. Says he'll bend them if they're not treated.

Naturally, if the whole piece is to achieve the same mechanicals after heat treat, it makes sense to use 4130 filler.

Have any of you guys done this? Any issues welding with 4130 filler? Preheat/weld/post heat?

I'm worried about cracking issues using 4130. Are my concerns valid, or should I stop thinking so much and just burn it in (tapering the torch off slowly)?

Bars will be 1" OD 16ga for what that's worth. I don't think he has anything to worry about in regards to strength, but I'd like to make them as strong as possible regardless.
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Old 06-19-2016, 07:24 PM
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. . . surprised that you haven't received a single reply.

Weld it with a matching filler pay attention to proper welding technique.
Back purge.
The heat treatment will basically be an anneal process as far as the Weld and the HAZ are concerned and as such should eliminate any of the cracking issue.
The trick may be warpage.


E

Coming back to this...
Looking at the part I'm thinking that I might try(test) 308L.
Then take the test bar and toss it into a 450° oven for an hour then switching the oven off and letting it cool slow... and see if it warps, bends, checks, cracks, and if it is strong enough. I know that the HT procedure is completely wrong but it might be enough for the application...
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  #3  
Old 06-20-2016, 08:09 AM
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There are several good discussions at race-dezert.com about this topic. There doesn't really seem to be a consensus on it.

I don't have any experience getting my stuff heat treated, so I'm just repeating what I've read. Generally, you would be sending the part through a quench and temper process to achieve something in the range of 28-32 hardness on the Rockwell C scale.

You are correct to be concerned about warpage, especially on something like handle bars. If you look at build threads on trophy trucks and the like, you will see extra pieces of tube tacked in place between the legs of control arms, and other long, skinny fabrications to limit the amount they move around during heat treat. Also, bores for spherical bearings are normally left undersize and machined post heat treat because they move around.

I think there are still a couple threads on this site by DUMP! that are entitled "Trophy Truck Lower Control Arm 101" or something similar that have a lot of detail.

To answer your original question, it varies depending on who is making the parts. It seems like most guys avoid using 4130 rod because it is "finicky", which I take to mean that it will crack if conditions aren't optimal. DUMP! and others have mentioned using ER80S-D2, which is a low alloy mild steel rod that a lot of people (myself included) like for general 4130 welding. Carroll Smith recommends Oxweld 32 (AKA RG-65), which is an alloy gas welding rod that contains the right elements to respond to heat treating. There's also another school of thought that using ER70S2 is sufficient because the weld picks up enough alloying elements from the parent metal to be affected by heat treatment, yet remains more ductile than the surrounding metal.

If you can find DUMP!'s threads, he also talks about some of the considerations that you have to make for venting a part to keep it from ballooning during the heat treat process. There are a lot of details involved in the part design to make good heat treated parts.
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Old 06-20-2016, 09:23 AM
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Awesome info guys. Much appreciated. I want to digest your comments before replying with my own, but I'll leave you with the current bar design so you can see what I'm trying to make. Attaching the rolled tube will require a good amount of welding. Distortion is absolutely a concern, both during the welding process as well as heat treat.

31.5" wide, 4" rise, 15° backsweep. Modeled using my 1"OD 3"CLR die.

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Old 06-21-2016, 12:35 PM
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Let's throw some numbers at this thing. For the sake of clarity, I'll be listing mechanicals in the following form: tensile (ksi) - yield (ksi) - percent elongation at failure (%).

I ordered the tube from onlinemetals.com and they fail to specify the condition in which their 4130 tube is supplied. I'm not sure this will prove to be relevant since it's being heat treated, but here's the numbers for 4130 in both the annealed and normalized condition per matweb.com (rounded down to the nearest ksi).

4130 Annealed: 81-66-21
4130 Normalized: 97-63-25

As quench and temper to 35 HRC will yield 161-138-14.

Huge increase in strength. Materials are awesome. Note the reduction in elongation, however. That being said, cold drawn 1018 only has 15% elongation at break, so I'm not overly concerned.

Moving on to the filler wire, ER70s and ER80s will have 70 and 80ksi tensile respectively, with ER80s better matching the tensile of annealed 4130. Before we get ahead of ourselves, we need to look at chemistry as well.

Carbon, Chromium, and Molybdenum will all influence the hardening characteristics, so we'll concentrate on those alloying elements. Numbers are from Harris.

4130: .28-.33% C, 0.8-1.1% Cr, .15-.25% Mo
ER70s-2: .15% C, Negligible Cr, Negligible Mo
ER80s-D2: 0.8-.12% C, Negligible Cr, .4-.6% Mo
308L: .04% C, 18-21% Cr, .75% Mo

I didn't bother to look it up, but I assume 4130 filler is indeed 4130, which will have the same chemistry as the base material as specified by AISI.

ER70 and ER80 are essentially a wash, and I'd most likely select ER80 due to the slightly higher tensile and the addition of a little moly. 308 is interesting. Relatively low carbon, but huge chrome numbers. The chrome will help drive the hardness into the weld, however the low carbon will limit the hardenability. Even with the dilution of the weld puddle, I don't think it'll take in enough carbon to rival the hardness of the parent material after heat treat.

4130 filler is still a bit intimidating due to the crack sensitivity.

I'm leaning towards ER80 right now. Higher strength to start with, moderate carbon content, and it has some moly to help with heat treat. Hopefully the dilution will ramp up the carbon a bit, helping out with the hardenability. I don't think the result after heat treat will match the parent material, but it would much closer to it than 308.

Let me know your thoughts, gents. I may have more to add later, but those are my brain dumpings for now.
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Old 06-21-2016, 01:03 PM
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Another one to consider is Oxweld 32/RG-65. (0.15% carbon, 1.10% manganese, 0.25% silicon, and 0.30% chromium). I have welded a fair amount of stuff that wasn't heat treated with this rod and have been happy with the results. It lays down nice and I never had any failures, crashes resulted in tearing the tube in the HAZ. The makeup is pretty close to ER80S-D2, only it uses chromium in place of moly.

It's available from Aircraft Spruce for less than $10/lb.

The tough part with this is the makeup of the weld itself is a bit of a guess since it's a mixture of the parent metal and the filler. I don't think you are going wrong with either ER80S-D2 or RG-65.

I would not use 308 stainless. I think you run a real risk of having very hard/brittle welds due to the high chromium content.
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Old 06-21-2016, 01:06 PM
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Here's a link to a thread on race-dezert with a lot of good info. On the second page there's a table comparing chemistry of some common filler choices.

http://www.race-dezert.com/forum/thr...es-what.56439/

On edit: It looks like the table has the properties for ER80S-D2 and ER80S-B2 flopped.

Last edited by Graham08; 06-21-2016 at 01:15 PM.
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Old 06-21-2016, 01:43 PM
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sidewayz...

I think you might be served by getting the relevant maximum loading numbers.
I suspect that ultimate strength is not needed, nor I suspect, even desirable.

Yes, I am suspecting that a human-being will never bend the HT bars without breaking breaking bones. If the human gets out of the way and the bar impacts an immovable object hard enough, I would want the bar to give long before the mounting block/fork/headset, or frame.

Anywayz I think I would bend a bar and have it HT processed and ride test it w/o the cross tube... Might work... might not

I switched to Aluminum bars a decade ago= (Give or take) 300MPA yield/tensile.

E
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Last edited by entropy; 06-21-2016 at 01:50 PM.
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Old 06-21-2016, 01:47 PM
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Quote:
Originally Posted by Graham08 View Post
I would not use 308 stainless. I think you run a real risk of having very hard/brittle welds due to the high chromium content.
In this application I doubt that it is a concern particularly with HT.... Welds up nice.

Been wrong before
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Last edited by entropy; 06-21-2016 at 01:51 PM.
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Old 06-21-2016, 02:25 PM
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There are two different 308 fillers that I'm aware of. 308L and 308H. The 308H has a higher carbon content that would respond better to hardening. It's 0.04-0.08% carbon.
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Old 06-21-2016, 02:26 PM
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Do you guys know of any negative effects of using a lower strength (low carbon) filler, other than the lesser ability to respond to heat treating? Is the only downfall lower strength local to the weld?

If that's the case, I may be OK with just using Er70s-2. I'll run some calcs and report back with my findings.
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Old 06-21-2016, 02:40 PM
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Quote:
Originally Posted by Bray D View Post
Do you guys know of any negative effects of using a lower strength (low carbon) filler, other than the lesser ability to respond to heat treating? Is the only downfall lower strength local to the weld?

If that's the case, I may be OK with just using Er70s-2. I'll run some calcs and report back with my findings.
Again I ask how much strength is required?

Until you can answer that, nobody can answer the question...
I'll bet that having a yield between 40k and 60k is more then plenty.
I say that and I fully admit that I might be wrong!
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Old 06-21-2016, 02:44 PM
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More numbers. I'm starting to gain confidence that the low strength filler will be sufficient, but this is a good discussion/exercise regardless.

I ran a calc to find the theoretical force necessary to yield the bar if it were a straight piece, 31.5" long (design width), and supported at the very center of the bar.

Even if the whole piece was made from the lowest strength material that we've considered (60ksi yield Er70s-2), it would require a force of just under 160lbs on each hand. I.E. he would need to be able to bench press 320lbs to start to bend these things. Highly unlikely.

If we take it a step further and look at 4130, it has a 66ksi yield in the annealed condition. 350lb bench press.

Any amount of a proper Q&T will increase the strength of the bars significantly. I don't think he'll have any problems. Not to mention, these will have multiple bends as well as a support tube which will add more strength.

Now I'm leaning towards Er70s-2 filler. I have it on hand, know how it welds, low risk of weld cracking, and should be more than strong enough. The dilution of the weld puddle will introduce some carbon that will ramp up the strength of the weld as well.

Am I veering off the track of righteousness?
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Old 06-22-2016, 01:43 PM
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But........what are the G forces he will be subjecting the bars to while riding.....it its 10 G on a jump landing he could bend that straight bar real easy.......
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Old 06-22-2016, 01:52 PM
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I disagree. Regardless of the scenario, his body needs to be capable of producing the force necessary to bend them. If he can't physically create 300+ lbs of force, he can't physically bend them. His muscles will fail before the bars do.

Another scenario to consider is the bike landing on the bars during a crash. It would be extremely difficult to approximate the impulse loading in that case, and I don't think I'm responsible for preventing failure in that regard anyways.

If he ghost rides it off a mountain and ends up bending the bars, that's on him, haha.

edit: Inertial forces of the bars play a roll as well, but being approximately 2lbs, the effect is negligible.
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Old 06-22-2016, 02:10 PM
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But........what are the G forces he will be subjecting the bars to while riding.....it its 10 G on a jump landing he could bend that straight bar real easy.......
Without damage just how much force can a statistical median human arm assembly transmit before failure?

Designing for the mechanical ingratiation of the human into a machine is completely different then designing a machine to protect/project the human.

Way interesting thread

E
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Old 06-22-2016, 02:17 PM
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You're spot on, E. Since my buddy is the one creating the forces that go into the bars, we have a pretty good idea of the loading limits and resulting stresses. That's rarely the case with stuff I work on, but a welcomed bit of info for this project.
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Old 06-22-2016, 02:43 PM
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Quote:
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Without damage just how much force can a statistical median human arm assembly transmit before failure?


E
I thought professional boxers punch with 1000lbs plus of force.
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Old 06-22-2016, 02:58 PM
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I don't know actual numbers, but the inertial loading the rider would put on the bars can be pretty high landing a jump or doing something similar. I don't know that the amount someone can bench press is really the same thing as the max load you could exert in this scenario without injury.

Are these going on a suspension bike? If you know the front spring rate and max travel, you could get a pretty good idea of what the max load might be.
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Old 06-22-2016, 03:05 PM
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Quote:
Originally Posted by entropy View Post
In this application I doubt that it is a concern particularly with HT.... Welds up nice.

Been wrong before
Now that I think about it, I'm wrong. 300 series stainless is not heat treatable. From material descriptions on Speedy Metals site:

"304/304L is not hardenable by heat treatment. Cold working increases tensile strength and hardness. Annealing range is between 1850° and 2050°F. Cool rapidly. Water should be used for heavier sections; air for lighter sections. The stress relieving range is between 400° and 750°F."

I have seen 309 recommended for 4130 due to the high elongation value...I have a really old article in my files with testing to back it up. If I get a few minutes I'll have to dig out and scan.

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