Author Topic: welding chromoly to mild.....any issues?  (Read 38580 times)

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Offline willieworld

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Re: welding chromoly to mild.....any issues?
« Reply #15 on: April 24, 2008, 12:13:34 AM »
last of pics
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Offline Sumner

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Re: welding chromoly to mild.....any issues?
« Reply #16 on: April 24, 2008, 12:30:36 AM »
Good stuff Willie, thanks. I'd like to see how you are bending/breaking it in the press.  You don't need to stick a new piece in there, just the bent one.  I think I would be afraid of it flying out of the press.  I don't like things under compression.  I had a good friend loose an eye two years ago pressing bushings into an a-arm and he had done it hundreds of times before at his parts store.  I always wear a face shield now when pressing something.

I might want to try this and would like the see the successful method of using the press.

Thanks,

Sum

Offline Harold Bettes

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Re: welding chromoly to mild.....any issues?
« Reply #17 on: April 24, 2008, 03:03:00 PM »
Willie, 

You sir are a craftsman, scholar, and a gentleman. :-D Your kindness is only exceeded by your skill. :lol: Wow that sounds cheesy, but I think that it is true from what I have seen.

Thank you so much for doing all the work and supplying the pics. You made the best statement about the brittleness of the welded area and that was what I wanted to verify.  :-o :roll:

Although the failure just outside the welded area appears to be a somewhat classic martinsitic failure, the test is fairly conclusive in my opinion. 8-) :?

I think that CrMo is one of the most overrated and misunderstood materials for use in racing. It has its place, but it also has its inherent dangers. And jsut because somebody that can spell TIG or buy a machine should not necessarily be the guy that welds up a cage or a chassis. There is a whole other discussion of using condition N vs hardened condition CrMo that is perhaps beyond this venue because of the things that you have shown us all. 8-) CrMo is bad ju ju for roll cages for all the reasons that are obvious in your testing.

I look forward to your comments and a pic like Sum has requested on how the samples fit into place in your press. 8-)

Hoping that you have a great day.Thanks again. :-)

Regards,
HB2
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As iron sharpens iron, one man sharpens another.

Offline willieworld

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Re: welding chromoly to mild.....any issues?
« Reply #18 on: April 24, 2008, 05:10:56 PM »
There's a couple of pics with the press, the way I press stuff. Fortunately the pump for my press is on the side, which allows me to kind of hide behind the upright. Seeing a guy with a piece of plywood and a rope with the rope dangling around his neck and the plywood dangling down in front of him when he operated this press, gave me a great idea which you will see in the second set of pics. I've devised what I think is the perfect shield. Here are the pics of the press....

Willie Buchta
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Offline willieworld

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Re: welding chromoly to mild.....any issues?
« Reply #19 on: April 24, 2008, 05:12:02 PM »
Here are the pictures of the shield.



































enjoy....
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Offline Rex Schimmer

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Re: welding chromoly to mild.....any issues?
« Reply #20 on: April 24, 2008, 05:27:48 PM »
I think that Willie and Harold are right about using Chrome Moly for our kind of racing. It just doesn't compute, you buy a material that is much more expensive, Willie has shown what the welding problems are and what do we gain? We save a few pounds so that we can add ballist??? Don't make much sense.

The post weld heating of the weld area that Willie did probably shows that this type of joint will adsorb more energy during a crash before failing and that a similar joint that was not post heated would probaby fail in a big bang. If you use mild steel you get the same charteristics and save money and the PITA(Pain In The A$$)of having to mess with 4130.

I was pretty good friends with Doane Spencer and he built some pretty nice race car stuff and he absolutely would not use chrome moly tubing and just for the reason that Willie has shown us in his testing.

Thanks Willie!!!

Rex
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Offline Sumner

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Re: welding chromoly to mild.....any issues?
« Reply #21 on: April 24, 2008, 05:57:38 PM »
Here are the pictures of the shield.
enjoy....

Thanks for the pictures I was having a hard time visualizing how you did it. 

Well at least one of you behind the shield is good looking and sorry, but it ain't the one with the beard  8-),

Sum

Offline willieworld

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Re: welding chromoly to mild.....any issues?
« Reply #22 on: April 24, 2008, 07:20:36 PM »
i guess in all fairness i should do a mild steel to mild steel and i will as soon as i get a chance   willie buchta
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Offline isiahstites

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Re: welding chromoly to mild.....any issues?
« Reply #23 on: April 24, 2008, 09:09:11 PM »
i guess in all fairness i should do a mild steel to mild steel and i will as soon as i get a chance   willie buchta

I was going to ask that you do that, I would be greatful if you did!

Also guys, what about the differences between DOM steel and welded seam? Can someone shed a little light on the differences of these two types of tubing?

Scott

Offline willieworld

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Re: welding chromoly to mild.....any issues?
« Reply #24 on: April 24, 2008, 10:13:47 PM »
scott  the only differance ive found between ew and dom is the thickness (im talking about 1/2 inch up tp 2 inch od) all electric welded (seamed) tubing is not what it appears to be it has a nominal wall thickness which means its made from flat plate then rolled into a tube and welded and according to mill specs .120 wall can be as thin   .110 but usually is .114 to .115 ---the mininum wall thickness for nhra is .118 in mild steel so i always have to use dom  --if you buy .120 dom it will pass tech for nhra --i have a sonic checker and check all my tubing--if you dont you can buy .125 wall dom ---they dont make ew in .125 although i have seen and used some .134 wall ew but its hard to find in anything other than 1 5/8 or 1 1/4 od --i think the scta rule book says nominal wall thickness so ew will be fine if your worried you could buy .120 wall dom but i dont think .004 or .005 of an inch will make any differance in a crash---i think what will make a differance is a properly designed and welded and gusseted roll cage --i build a lot of bike frames (no roll cage) and i always use dom  just because i always have --also remember that the cheapest tube you can buy ( EW ) is still about .015 thicker than the most expensive (cm)    parden the spelling  willie buchta
« Last Edit: April 25, 2008, 11:44:18 AM by willieworld »
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Offline GeneF

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Re: welding chromoly to mild.....any issues?
« Reply #25 on: April 24, 2008, 10:29:34 PM »
i guess in all fairness i should do a mild steel to mild steel and i will as soon as i get a chance   willie buchta

I was going to ask that you do that, I would be greatful if you did!

Also guys, what about the differences between DOM steel and welded seam? Can someone shed a little light on the differences of these two types of tubing?

Scott

 DOM is welded seam tubing, after its welded it is Drawn Over a Mandrel which smooths and sizes the i.d. Essentially a cold working process that gives it higher strength also.

Offline willieworld

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Re: welding chromoly to mild.....any issues?
« Reply #26 on: April 25, 2008, 11:45:15 AM »
i corrected that   willie buchta
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Offline willieworld

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Re: welding chromoly to mild.....any issues?
« Reply #27 on: April 25, 2008, 04:36:45 PM »
o k guys i think this will be my last post on this subject--the tubing is dom .120 wall both pieces --a couple of things the pressure was about the same as the heated cm --the main tube was distorted a lot not as much as the heated cm but the tubing was thicker and should of distorted less which it did--the tubing ripped close to the weld which is usually the case with mild steel --my advise is no matter what you weld spend a day and do some testing i think the tubing type is probably less important than the design the welds and proper bracing and dont forget those gussets   thanks  willie buchta
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Offline willieworld

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Re: welding chromoly to mild.....any issues?
« Reply #28 on: April 25, 2008, 04:37:37 PM »
more pics
willie buchta
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Offline Peter Jack

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Re: welding chromoly to mild.....any issues?
« Reply #29 on: April 25, 2008, 06:02:32 PM »
Thanks Willie.

This has been a really helpful and informative session. In all my years of fabricating I haven't used an approach like that for testing myself and my results. I have tested individual projects at various times. I think from now on I may do a little more self testing.

It's postings like this series that makes these forums so valuable.

Pete