Stress Relieving

JOSH

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How do you guys Stress Reliev your cages, can you do it with a torch???
any info???
-thanks
Josh
 

Greg

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Stress relieve!!! we dont need no stress relieve!!!

Greg
 

Kritter

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you dont, unless you have an oven the size of the car. Some people say a torch works but that is jsut making other areas brittle. Jus build it right and it should be fine.

Kris

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BIG_FAT_LOSER

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Stress relieving = Full release? Just curious. lol

<font color=red>PAT KAPKO</font color=red>
<font color=yellow>Self appointed King of ghetto fab</font color=yellow>
 

JCA

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I go out and beat the s**t out of my truck! I dont know about you but that relieaves some stress!!! :)

J.C. Andrews
Andrews Racing
www.andrewsracing.com
 

partybarge_pilot

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Stress reliving with a torch is imposible to do correctly on a large tubular weldment (cage). It doesn't make that large of a differance on non heat treated materal anyways. Are you MIGing or TIGing? Ever stop to think if your useing the right alloy wire for 4130?

<P ID="edit"><FONT SIZE=-1>Edited by partybarge_pilot on 05/15/02 09:14 PM (server time).</FONT></P>
 

ntsqd

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The easy way to stress relieve 4130 is to gas weld (Oxy-fuel) it as that is what it was originally alloyed to be welded with. This resulted in a noramlized condition when allowed to slow cool in still air.

In theory you can weld with a TIG and then go along with a rosebud to heat each joint up above the critical temp and then allow it to cool in still air. I agree with the other postings though, you really can't do a proper job of it that way.

TS

"Teach you all I know and you're still stupid"
-- Howdy Lee
 

V8Ranger

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taken from http://www.hi-techwelding.com/4130cm.htm:
6) Do I heat treat 4130 after welding?
A. NO! The term "heat treat" has been generically misused in the welding field, as has normalizing. Heat treat and normalizing operations are extremely sensitive to heat control (preferably oven-controlled) and do metallurgically change the strength value of the parent material. Stress-relieving is the recommended practice and 1,100ºF is the optimum temperature for tubing applications. Use temperature crayon 900ºF and mark approximately 1" away from weld areas. Use Oxy/Acetylene torch with neutral flame and oscillate to avoid hot spots.
NOTE: Excessive stresses are induced by too much heat input, poor fit-up, or both, therefore stress relieving can be avoided if all fit-ups are precision (using tools like the "'Ol Joint Jigger") and applying minimum heat input, i.e. smaller welds. TIG welding should not require a weaving pattern in the welding technique.

From "Engineer to Win" by Carroll Smith:

When he is talking about SAE 4130 he states: "It is critical that all welds be stress relieved. " "Since I believe not heat treating 4130 fabrications is DUMB (if you don't heat treat you end up with an expensive part with the same strength of 1020-and brittle weld areas)"

In another chapter Smith goes on to talk about stress relieving and the process of "torch normalizing." He recommends heating the welds to a dull cherry red color with a rosebud tip. This corresponds to the stress relieving temperature of 1100 to 1250 degrees F. The part is then either immersed in DRY sand or allowed to cool in STILL air. He goes on to say, too little heat is better than too much. The part should never actually reach a red color.

This goes against what I have learned ( what Kritter stated above). Now I'm just confused! Who knows who is right.
 

AZmiik

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As a welding major I have had a few in depth conversations about this subject over the last few weeks. I would agree on most of what is stated above. Fit up is one of the most critical steps. Any way I just thought I would share some stuff about this from Lincoln Electric.

Q. Do I need to pre-heat?
A. Thin wall tubing (< 0.120" wall) applications do not typically require the normal 300?F to 400?F pre-heat to obtain acceptable results. However, tubing should be at room temperature (70?F) or above before welding.
<http://content.lincolnelectric.com/graphics/knowledge/articles/content/chromemoly1.jpg>

Q. What filler material do I use?
A. Although there are several good filler materials, ER80S-D2, is one you should consider. This filler material is capable of producing welds that approximate the strength of 4130. ER-70S-2 is an acceptable alternative to ER80S-D2, as is ER70S-6, although the weld strength will be slightly lower.

Q. When I use ER70S-2 filler material, do I give up strength for elongation?
A. Yes. The filler material, when diluted with the parent material, will typically undermatch the 4130. However, with the proper joint design (such as cluster or gusset, for example), the cross-sectional area and linear inches of weld can compensate for the reduced weld deposit strength.

Q. Why is 4130 filler metal not recommended?
A. 4130 filler typically is used for applications where the weld will be heat treated. Due to its higher hardness and reduced elongation, it is not recommended for sporting applications such as experimental airplanes, race car frames, roll cages, etc.

Q. Do I need to heat treat (stress relieve) 4130 after welding?
A. Thin wall tubing normally does not require stress relief. For parts thicker than .120", stress-relieving is recommended and 1,100?F is the optimum temperature for tubing applications. An Oxy/Acetylene torch with neutral flame can be used. It should be oscillated to avoid hot spots.
<http://content.lincolnelectric.com/graphics/knowledge/articles/content/chromemoly2.jpg>

Q. Do I have to pre-clean 4130 material?
A. Remove surface scale and oils with mild abrasives and acetone. Wipe to remove all oils and lubricants. All burrs should be removed with a hand scraper or de-burring tool. Better welding results with clean materials.

Q. Do I need to back-purge 4130 material?
A. Backpurging is not normally necessary, although some fabricators do. It will not hurt the weld and may improve the root pass of some welds.
.

Q. Should I quench the metal after I finish welding?
A. ABSOLUTELY NOT! Rapid quenching of the metal will create problems such as cracking and lamellar tearing. Always allow the weld to slow cool.

Mike
 

Dave_G

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Matt,
In my opinion, Carroll Smith has it correct. Some of the most winning teams like Enduro ( former Duralast) and others do this process religiously and they have had great success with it. You can't knock what works and will never make this 4130 controversy die. When you weld a band saw blade together you have to stress relieve the weld area in the same manner that Smith describes or it will break. Granted the blade is not 4130 but we do this kind of thing every day at my shop. This is NOT voodoo science.


"In America we allow stupid people to say stupid things.
That way the rest of us know who the stupid people are!"

Quote: Ted Nugent on Fox News 5/15/02

Best,
Dave

"I know it all, but I can't remember most of it..."
 

Kritter

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Straight from the welding innovators and experts. Not sure what you would need more then .120 4130 for a prerunner so not really necissary

"Q. Do I need to heat treat (stress relieve) 4130 after welding?
A. Thin wall tubing normally does not require stress relief. For parts thicker than .120", stress-relieving is recommended and 1,100?F is the optimum temperature for tubing applications. An Oxy/Acetylene torch with neutral flame can be used. It should be oscillated to avoid hot spots."



Dave: Not to talk trash because I think Enduro is awesome, but arent they chasing cracks like crazy on that truck?

Kris

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JCA

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My whole truck is 4130 from the cage to the frame strengthing. I have not chased one crack. Granted I have chased motor issues and springs and still need to dial the truck in on other stuff but no cracks. I have heard the same thing about Enduro as well as others but that is total diffrent speeds and that changes everything. But Brad some times I get the feeling that you Think of yourself as part of the ELITE and not realistic. Just look at the quotes you put on your post.

J.C. Andrews
Andrews Racing
www.andrewsracing.com
 

Dave_G

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RE: Not to talk trash because I think Enduro is awesome, but arent they chasing cracks like crazy on that truck?

Kris,
Yes they are, but most of them are not occuring in the weld areas. Their seeing cracks develop in certain structural sections from cyclic fatigue. You got to remember that truck is over 4 years old now and has seen it's fair share of cycles on the frame. ;-)

Dave

"I know it all, but I can't remember most of it..."
 

FABRICATOR

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JOSH,
All you NEED to know can be found at: <A target="_blank" HREF=http://link>http://www.lincolnelectric.com/knowledge/articles/content/chrome-moly.asp</A>
The 1100F degree mark can be monitored with temperature indicating markers or approximated by a dull red glow in a dimly lit area.

Others,
Stress relieving and heat treating are two entirely different things.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>
 

V8Ranger

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Yes, I agree that stress relieving and heat treating are different but I think you are taking it to the extreme to say that they are "entirely different things."

Taken from Carroll Smith's "Engineer to Win":

"All heat treatments involve heating of the metal, holding it at a given temperature for a specified length of time (soaking) and then cooling to ambient temperature. The individual processes achieve their different results by variations in the temperatures reached, the length of the soaking period and the rate at which the metal is cooled."

" Stress relieving is the heating of a ferrous alloy to a suitable temperature within the critical range, holding it at that temperature long enough to reduce internal stresses and to refine the grain structure, and then cooling the new steel slowly enough to minimize the development of new internal stresses."

While Stress Relieving and Heat Treating accomplish two different things, their processes are very similar.
 

ntsqd

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"Yes they are, but most of them are not occuring in the weld areas. Their seeing cracks develop in certain structural sections from cyclic fatigue. You got to remember that truck is over 4 years old now and has seen it's fair share of cycles on the frame. ;-) "

Sounds to me like that chassis is nearing the end of it's fatigue life. Time to build another. That is my argument against 4130 for anyone not able to afford tossing a used chassis and building a new one.

TS

"Teach you all I know and you're still stupid"
-- Howdy Lee
 

ntsqd

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"While Stress Relieving and Heat Treating accomplish two different things, their processes are very similar."

And therein lies the schemantics (sp ?) problem, "Heat Treating" is both generic and specific depending on the context and intent of the conversation.

TS

"Teach you all I know and you're still stupid"
-- Howdy Lee
 
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