Chromoly vs DOM

[Sherman_thetank]

Any thoughts? I'm thinking of using industrial grade Chromoly on my long arms i will be building, has anyone used this, and any problem you had, or can foresee?
Thanks
Alex

 

[Grant]

Any thoughts? I'm thinking of using industrial grade Chromoly on my long arms i will be building, has anyone used this, and any problem you had, or can foresee?
Thanks
Alex

in order to make full use of chromoly, you need to plan on normalizing the structure after welding (an oven is best, but oxy/acet will do) Otherwise, DOM is better value for money. Is weight really an issue? or are you scoring the chromoly dirt cheap?

define industrial grade Chromoly please, I have never heard it referred to in that fashion before.

Grant

 

[Sherman_thetank]

Industrial grade is the highest load rated steel you can buy that I'm aware of, High strength DOM is in the area of about 80-85000 psi and the Industrial grade Chromoly is 120000 +
And yes i have a source to get it for almost nothing. As far as normalizing it you basically mean just heating it up?
Heres an article that explains it pretty well.
http://www.4wheeloffroad.com/techarticles/body/131_0602_4x4_buggy_building_tubing/index.html

 

[asp]

normalizing means changing the structure of the molecules back to homogeneous, rather than what it would be after welding. welding moves everything around and gives metal different propeties (duh) and heating up the metal to about 500 degrees, maybe a bit hotter depending on the metal in question will help to eliminate the weld's brittle tendancies.

 

[Phil]

Industrial grade is the highest load rated steel you can buy that I'm aware of, High strength DOM is in the area of about 80-85000 psi and the Industrial grade Chromoly is 120000 +
And yes i have a source to get it for almost nothing. As far as normalizing it you basically mean just heating it up?
Heres an article that explains it pretty well.
http://www.4wheeloffroad.com/techarticles/body/131_0602_4x4_buggy_building_tubing/index.html

Yield or UTS?

 

[asp]

i'd be interested in the stress-strain curves of both, too...usually the higher the yield, the less strain it takes to get to the UTS...

 

[Sherman_thetank]

Yes the actual yeild strength for the tube, which i assume they mean the resistance to bending :dunno:
This is the pic from the article, (too bad they labeled the tubing backwards)
But just from looking at it the Chomoly is un-hurt. My dad is the one who recommended it to me because he uses it a lot when ordering supplies for new projects (hes a cival engineer)

 

[XJ_ranger]

If I dont decide to run AL links if/when I link the rear of my junk - I'll run these...
http://www.spidertrax.com/products/Chromoly-Links

 

[5-90]

One small point...

"Chromoly" is a material - typically a 41xx or 43xx steel alloy, using carbon, chromium, and molybdenum (thus, "chromoly.") It was actually developed for a specific purpose - to facilitate flame torch welding while minimizing harmful effects from the welding process. Chromoly should be welded using a slightly "carbonizing" (read: rich) flamp using oxyacetylene.

"DOM" - "Drawn Over Mandrel" - is a process whereby tubing is made. It has little to nothing to do with material (although some materials make better DOM tubing than others,) and is typically characterised by lack of a welded seam as you'd find on HREW (Hot-Rolled Electrically Welded) or CREW (Cold-Rolled Electrically Welded.) Both of these will have weld seams down one side, although CREW tends to have less scale formation on the tubing than HREW, simply because when steel is hot-worked, it forms a scale as it cools (which results in a need for "pickling" - an acid bath to remove scale from hot-worked steel.)

 

[Goatman]

If you're not an expert welder, or have a friend that's an expert welder who will do the welding for you, I'd stick to the DOM. The quality (strength) of the weld, rather than the strength of the material, becomes the issue when talking chromo vs DOM. The DOM will weld up just fine and be strong. The chromo can much more easily have a weak weld (brittleness at the edge of the weld) and end up being weaker overall than the DOM.

 

[Jump This]

I'd suggest DOM just because I am a tight wad bastard...

But that's just me.

 

[Jes]

I went with 2"X.25" chomoly for my lowers simply because I got it for a good price and the welders at URF Racing are super.

 

[Sherman_thetank]

I went with 2"X.25" chomoly for my lowers simply because I got it for a good price and the welders at URF Racing are super.

That is exactly what i am looking at. I am a decent welder, so i was going to tack it together and then have my friend who is very good, finish them up for me. Thanks for all the input guys i'm hoping to see how much of a break im gonna get on this stuff soon, or i will just be ordering up so DOM.

 

[Skullver]

here is an interesting link about welding 4130 tubing:

http://www.netwelding.com/Welding 4130.htm

 

[Weasel]

your numbers are off for what matters. Chromo is only ~10% stronger in it's raw form then DOM. Welding should be no different then DOM use the same welding rod. Links are not thick enough to cause any brittle welds. Never heard of industrial chromoly it's all the same stuff. It does resist denting better but could be a mute point for the price.

Spidertrax links are the way to go.

 

[Sherman_thetank]

Thanks! Thats alot of reading there, but some good info

 

[Sherman_thetank]

your numbers are off for what matters. Chromo is only ~10% stronger in it's raw form then DOM. Welding should be no different then DOM use the same welding rod. Links are not thick enough to cause any brittle welds. Never heard of industrial chromoly it's all the same stuff. It does resist denting better but could be a mute point for the price.

Spidertrax links are the way to go.

1.

DOM ratings range from 60,000 to 70,000 yield and 70,000 to 80,000 ultimate strength, though when I looked at the actually mill test report of the tubing, it had numbers about 5,000 psi above these required minimums. Chromoly has numbers in the 80,000 to 85,000 psi range for yield depending on whether the tubing is stress relieved (slightly lower numbers) and 90,000 to 95,000 ultimate strength, but again actual mill test results for chromoly from Industrial Metal Supply had yield at around 110,000 and ultimate strength at over 120,000.

2.Did you read this
http://www.netwelding.com/Welding 4130.htm

 

[Weasel]

look up 4130 and 1020 or 1018 at Matweb.com Various strengths may vary but general those at Matweb are the best estimates of strength.

Ultimate strength is pretty much worthless cause at this point the link has broke and your screwed.

As for welding the metal cannot cool fast enough to get brittle, steel is not thick enough. We've welded 12 race chassis with 4130 and ER70 rod and had zero issues period.

Twisted Customs weld all of their chromoly tubing with the same filler and never had any welding issues.

DOM/chromoly 0.5" walls lower arms bend basically same amount. Spidertrax 0.125" don't and are perfectly straight.

 

[Sherman_thetank]

look up 4130 and 1020 or 1018 at Matweb.com Various strengths may vary but general those at Matweb are the best estimates of strength.

Ultimate strength is pretty much worthless cause at this point the link has broke and your screwed.

As for welding the metal cannot cool fast enough to get brittle, steel is not thick enough. We've welded 12 race chassis with 4130 and ER70 rod and had zero issues period.

Twisted Customs weld all of their chromoly tubing with the same filler and never had any welding issues.

DOM/chromoly 0.5" walls lower arms bend basically same amount. Spidertrax 0.125" don't and are perfectly straight.

Ok, so what make them different? Are they made from a different material then?

 

[Weasel]

Spidertrax's? Um heat treated 4130?