Saturday Night Racer

Saturday Night Racer
http://www.latemodelracer.com/cgi-bin/yabb2/YaBB.pl
Saturday Night Racer >> RACE TECH >> Chrome moly and heat
http://www.latemodelracer.com/cgi-bin/yabb2/YaBB.pl?num=1323483316

Message started by imracin68j on 12/09/11 at 6:15pm

Title: Chrome moly and heat
Post by imracin68j on 12/09/11 at 6:15pm

How much heat can Chome moly take? Does it loose all it's tensile strength when turned ruby red?

Title: Re: Chome moly and heat
Post by mudslinger47 on 12/09/11 at 6:18pm

Captian is on the Toys for Tots cruz night, he'll be back in a while to answer your quandry .

IM him so he notices

Duane

Title: Re: Chome moly and heat
Post by formercrewguy on 12/09/11 at 6:34pm

When you heat CM to the melting point (welding) it isn't CM anymore. It needs to be re-heat treated.

Title: Re: Chrome moly and heat
Post by imracin68j on 12/09/11 at 7:02pm

I actually had to burn off some old powder coat with a rosebud. I don't know if I got it to weld temps but warm enough to flake powder coat. I'm also going to rebake it in a powdercoat oven. Maybe that will re chrome moly.

Title: Re: Chrome moly and heat
Post by OLD SCHOOL#6 on 12/09/11 at 9:04pm

imracin68j wrote on 12/09/11 at 6:15pm:

How much heat can Chome moly take? Does it loose all it's tensile strength when turned ruby red?

Not all. It still has the strength of A-36, steel (not exactly, but close), but you will have lost the heat treated effect that makes it Chromoly ...... And, no the powder coating oven will not re-temper it back to Chromoly.
Next time, take the paint off with a sanding disc...........

Title: Re: Chrome moly and heat
Post by imracin68j on 12/09/11 at 11:14pm

It would be impossible to remove powedercoat with a disc without the risk of digging into the metal which is already at .058. Plus it would take about 10 times as long. The rosebud is the gold standard of removing powdercoat from what I've told. I had to torch off one section which I wasn't very happy about but gotta do what you gotta do.

Title: Re: Chrome moly and heat
Post by OLD SCHOOL#6 on 12/10/11 at 8:47am

imracin68j wrote on 12/09/11 at 11:14pm:

You have been missled ~~~~ a torch is "not the gold standard for removing powder coat". It is a "quick and easy" process. But in your case "quick and easy" should not have been the most important part of the job. If you are concerned that the material is to thin, and don't want to use a sanding disc, then a wire brush on a grinder will promptly send your powder coating to the floor. Naval jelly will also take it off ~~~ just a little more messy. Bottom line ---- a torch, in your situation, is acctually a last resort ~~~ as you have discovered. Your biggest problem was the thickness of the material. It took to much heat to burn the powder coat, and the material was to thin to handle it. If the material had been alot thicker, you would have been ok. Next time you get into something that might be a little out of your career field, you have my phone number, and you know I'll give ya' a hand ..........

PS -- If you were removing the powder coat because you needed to weld something there, I would not be to concerned. Welding Chromoly destroys the heat treated state and it is no longer Chromoly where the weld is. This is not a problem in your case becuase the weld is most likely to be greater in size than the thickness of the original material, and thus will be just as strong.

Title: Re: Chrome moly and heat
Post by formercrewguy on 12/10/11 at 9:22am

Yea......what he said^^^^^^^^^^^^^^^^^^^lol

Title: Re: Chrome moly and heat
Post by TIM_BEWLEY on 12/10/11 at 9:36am

OLD SCHOOL#6 wrote on 12/10/11 at 8:47am:

Welding Chromoly destroys the heat treated state and it is no longer Chromoly where the weld is. This is not a problem in your case becuase the weld is most likely to be greater in size than the thickness of the original material, and thus will be just as strong.

so i take it that's the case also on a stockcar chassis built out or cro mo? it is only lost in the weld area correct?

Title: Re: Chrome moly and heat
Post by OLD SCHOOL#6 on 12/10/11 at 10:57am

TIM_BEWLEY wrote on 12/10/11 at 9:36am:

OLD SCHOOL#6 wrote on 12/10/11 at 8:47am:

so i take it that's the case also on a stockcar chassis built out or cro mo? it is only lost in the weld area corretct?

Yes Sir -- that would be corectomundo. The welds are larger than the thickness of the material, thus making the weld area basically as strong as the CM. Basically the only time CM is re-heat treated after welding is in very high tech applications -- ie - areospace conponets.

Title: Re: Chrome moly and heat
Post by imracin68j on 12/10/11 at 2:45pm

I am bringing a piece of this powder coat and a wire wheel and will enjoy watching you send it to the ground. lol. It doesn't come off like paint. It swirls and melts in more. The heat generated with the wire will get the metal hot in itself. I can ruby red metal with a grinding wheel easy. You really don't ruby red the metal with torch, you're just lightly burning the powder. The powder coat absorbs most of the heat and flys off. I called MB products and American Fab and they both said heat is how they remove it. I run .058 on sunnies kart which is on the thick side. Some guys are running .035. Even with .060 grinding even a little into it will make it very thin. I'm thinking the powder coat ovens help the chrome moly a little.

BTW, I'm not having any metal issues. In fact I'm about to roll out one of my best creations to date. lol Everything is good I was just wondering if heat weakened the tensile strength of Chome Moly. Most karts are not using Chome Moly.

I think I'm going to do an experiment and really heat one piece of tubing up and let it cool and not the other and crack it with a sledge to see if it still holds up.

Here is a good thread on Chrome Moly welding and heat.
http://www.millerwelds.com/resources/communities/mboard/archive/index.php/t-11414.html

Title: Re: Chrome moly and heat
Post by OLD SCHOOL#6 on 12/10/11 at 4:42pm

Oki-dok --- sounds like ya' got it covered ....... Looking forward to seeing your latest creation ..........

Title: Re: Chrome moly and heat
Post by hogracer3d on 12/10/11 at 5:11pm

As a sandblasting contractor, I got your powdercoat removal huckleberry.

I can cut your tubing in half with the 275 hp air compressor, and a little dirt
Lol

Title: Re: Chrome moly and heat
Post by Ryan D. on 12/10/11 at 8:50pm

Well Im going to say Im a metal expert or a welder by trade by any means. Billy I know powder coating is the way to go, and looks really clean. But if your using wall thicknesses as low as .060 or even .035 where you say a wire wheel or grinding can cut into a tube and weaking it. I would ditch the powder coating, this would be the easiest answer.Besides who has a bare tube chassis showing off all the pretty welds and craftsmanship, and it would make repairs very easy.