chromoly

[fnkrngr]

What are you guys paying for 4130 1.5 tubing 95 wall?

You dont know the looks i get with this truck on the east coast.

[KitRacer]

i pay 2.62 a foot for .120, not sure about .095

At baseball games they play organs, in motorsports they donate them.

[Custom_Yota]

where do you get your chromoly at Kit racer? 2.62 a foot is a good deal. Is that price for everyone or just you? Regular mild is like 1.00 a foot so 2.60 isn't that much more.
thANX

[hoeker]

almost triple!!!!

the cost of moly is very, very dependent on how much you buy. my quotes for my new truck varied by 150%!!

FWIW...
for the novice / street vehicle stay away from moly! DOM in a crash may bend, saving your life. moly tends to crack. yes, all the best racecars are moly, including my new truck, but it took 2 months of talking to convince me to go moly even on my race truck. the biggest difference that i see is in a dedicated race vehicle there are way more bars than any part time race/street machine will ever have. strength in numbers! Another thing that would make me shy away is anything using a stock frame. you just can't engineer the thing good enough to make moly work. i am also going to use mild steel gussets at every joint to keep the joint from cracking.

i've seen some really scary results from crashes with moly, and these were cars built by some of the best fabricators in the country. make sure you know what you're getting into before building a moly cage.

my $.02

<A target="_blank" HREF=http://www.rosshoek.com>www.rosshoek.com</A>



Some are born great, some achieve greatness,
and some have greatness thrust upon them.

[KitRacer]

the deal is through my friend Seth at Amplified Performance, that is his cost, i dont know who he gets it from or how much he would resell it for, but i will ask next time i see him, i know that i can by one stick or a thousand sticks and its all 2.62 a foot. before Seth started helping me out, the best price i could get was 2.92 a foot and that was for about 400 feet

At baseball games they play organs, in motorsports they donate them.

[BA_DirtDriver]

Chromoly really needs to be heat treated to give you all the benefits of the material properties. Hoek is right on with the brittle failure or cracking that occures at the heat affected zone at the edge of the weld. Some people shot peen to stress relieve, but I am not sure of the effectiveness of it. Maybe someone can post some links to data on this.

[Kritter]

"i know that i can by one stick or a thousand sticks and its all 2.62 a foot" If you buy 1000 bars...you can beat that price easily...not that you would buy that many, but quantity is key in the mat'l market or any market.

Kris
<A target="_blank" HREF=http://www.barneysprecision.com/fabproducts.htm> Fab Parts</A>

[dunerking]

Just a little curious,but I'm not sure about the hole deal with the D.O.M. tubing.My last car was 100% chromoly,so I was just curious that when I go to start on my next car should I consider a D.O.M. chassis or stick with the chromoly?The chromoly treated me pretty well with the first car for type of driving I do.Just looking to get the heads up.

hit it hard

[Dave_G]

This thread is actually starting to crack me up!


Dave

"I started out with nothing and still have most of it left" http://www.race-dezert.com/wwwthreads/images/icons/cool.gif

[drtdevil93]

chromoly? come on.

with modern nutrition, human bones and muscle are stronger than ever. you dont need a cage that will hold up in a crash, you will probably heal eventually. i recommend using exhaust tubing, just to keep the race tech inspectors off your back. same for prerunners that want to be "that much cooler". and really, while im on the subject, automotive engineers are making things stronger than ever before, why upgrade suspension, or box frames, or install cages? i envision a future where there will be only one class in all desert racing: stock tacoma. who needs all that safety crap, and fuel cells, and upgraded brakes? waste of money. spend the money on stickers, paint, and a bumpin stereo.

erik

[hoeker]

you'll have to ask lots more people than me to decide that. my point was just that you need to be very careful with moly. moly is not better all the time.
if you're referring to another stock frame rig like your toy, i'd prefer DOM, but it's up to you. the thread "accident in glamis" a couple weeks ago showed plenty of reasons not to use moly. i'd give odds that if that had been a DOM car, it would still be in one piece. it would still be junk, but the passengers would have been in better shape.
you say you had good luck with it on your last car, that's great, but did you ever really crash it bad? probably not. a moly chassis, even if welded too hot, and not built right, may be fine until the one time you really need it. you may never find one crack, but when you roll it good and hard and your life depends on it, will it hold?? i have two months into building my new chassis, and i still hope i didn't make the wrong decision going moly. my old truck was DOM and it had been rolled at least twice before i bought it, then i rolled it twice more, once was a pretty hard roll. the chassis was perfect, no bends, no cracks, just put new sheet metal on and go. too many people think that moly is best because all the best racecars are moly. i just want people to realize it is not always best and needs careful consideration.
the first roll cage i ever built was an EW cage, i'd never do that again, but 2 years after i built it i "cartwheeled" the truck at about 50 mph. the whole truck was upside down 6-8 foot in the air, and came down hard, right on my head. this cage was not built properly, it was a nice street cage, not enough bars, no gussets. the entire cage collapsed 3", just enough to compress my spine and screw up my back, i lived, i can still walk, that cage saved my life even though it bent. if it had been molly, i'd lay odds it would have cracked at the lower windshield, and behind my head. who knows what condition i'd be in now.
the most important thing to remember when building a chassis, is good gussets and lots of them, this is even more important in a moly car. i am going to use mild steel gussets on my new race truck.

one more thing. moly is illegal in NASCAR.

<A target="_blank" HREF=http://www.rosshoek.com>www.rosshoek.com</A>

Some are born great, some achieve greatness,
and some have greatness thrust upon them.

[hoeker]

i don't get the joke? your talking about the single most important item in any off road vehicle. it's really no laughing matter.

Some are born great, some achieve greatness,
and some have greatness thrust upon them.

[drtdevil93]

ummm..... ok.

erik

[prerunner68]

If your so anti moly why build the new truck with it?
What is this?
Do as I say not as I do?
This thread is getting good.


You did what to the truck?

[jeff]

DOM da DOM DOM... DOM.

Couldn't resist. Just remember that each has its place and don't get too feisty over this - to each his own. Go over to PBB.com and you'll see a bunch of those guys swear by Schedule 80 pipe and believe it or not I think that even that stuff has it's place on certain vehicles (not a roll cage though).

Aloha

[hoeker]

i am jot anti-molly. as jeff said, each has it's place. re read my post i made my points clear. i had no intention of starting a big argument, molly just needs to be respected for it's weeknesses.

Some are born great, some achieve greatness,
and some have greatness thrust upon them.

[Billy_the_Kid]

I'm with Hoeker on this one too. I don't get your joke, or think it's funny to joke around about safety. Chromoly is not for everyone.

I think if you re-read the earlier posts, you'll see that that was the point these people were trying to make. No one is claiming to be anti-moly, they are just warning of the possible dangers of the misuse of a product. Example: just because someone installs a race seat and 5 point belts in their car doesn't mean it will save them in a crash if it was bolted to the floor boards with self tapping screws (I've seen that). The same is true with chromoly pipe, if it's not fabricated properly, it isn't any better or safer than DOM plain and simple.

And Prerunner68, you too are missing the point entirely. "do as I say not as I do" that's not at all what Hoek is saying. He's building the new truck with moly because he has the engineering and fabricating skills to do that.

The fact is, someone could build a roll cage from freakin pop cans, and if it's engineered properly, and put together by a fabricator who has the resources, skills, and know how, it will work.



Bill Schmitt

[Billy_the_Kid]

Here's one fabricators opinion, from Tech3 Motorsports FAQ's.

<A target=" blank" HREF=http://www.tech3motorsports.com/>http://www.tech3motorsports.com/</A>

7. Why do we use a Mild steel chassis as our standard vs Chromoly?

First of all we supply mild steel because we want our cars to stay affordable. Chromoly is about 3 times the cost of mild steel, it easily adds about $600 to the material cost. Thats not much, but when you look at what it takes to fabricate chassis with chromoly the labor costs and welding cost rise substantially over mild steel. Anyone will tell you mild steel is easier to work with and the processes of welding it is very defined. There is also a misconception about the weight savings, chromoly weighs the same as mild steel, its just that its twice as strong for the same thickness. Most builders are making chassis out of .083 chromoly with a little of .065 mixed in, which when combined is still stronger than the mild steel equivalent. It takes about 200 ft of materials to create a basic 2 seat chassis. 150 ft of 1.5 x .095 mild steel is about 219 lbs, 50 ft of 1 x .095 is about 50 lbs for a total of 269 lbs. The same in chromoly would be say 120 ft of 1.5 x .083 = 150 lbs, 30 ft of 1.5 x .065 = 30 lbs, and 50 feet of 1 x .095 = 50 lbs for a total of 230 lbs. That's only 39 lbs difference.

The second issue is stress relieving. Chromoly is much more susceptible to cracking after it has been welded especially if the grain structure has not been re-aligned thru a stress relieving process. Good welding processes, like cold welding, have evolved that help with this issue, but in reality heating a whole chassis for 2 days at 800 degrees is the proper way to do stress relieving. Boeing has done extensive testing on chromoly and have many extensive reports that can be found on the internet, or in the metals handbook. Obviously, nobody has that kind of oven or time to be doing that so welding processes have been perfected to help.

The rumors of a chromoly chassis being 4 times as strong as a mild steel chassis are absolutely not true. Especially when you consider the thinner tubing being used and all the complex angles.

Again we do believe in chromoly its just to stay affordable we offer mild steel to save costs, and also achieve a strong chassis. I have 6 hard years on my own mild steel .095 long travel chassis welded with our ESAB welder with no cracks.

Bill Schmitt

[CRAIGHALL]

As far as that accident in glamis goes I dont think funco or any other buggy manufacturer stress relieves thier chassis'.Dont use chromolly at critical points(cage) unless you plan on stress relieving it. And yes their are ovens big enough to stress relieve a frame. While maybe not perfect but better than not relieving is to use a temp stick (800-900 I think) or buttons on the frame about 3-4 inches from your cluster and heat very evenly.
while I'm no expert and dont have a degree I do know this needs to be done to properly put strengh in your welds.

Many buggy builders are only using chromolly because the uneducated customer only knows chromolly is stronger so it must be better. I know personaly about 4 years ago funco did just that(my family was going to buy one).

Craig

[prerunner68]

How much are the pop cans per foot? J/K

You did what to the truck?

[Billy_the_Kid]

10 cents per can in Michigan :)

Bill Schmitt

[SpareChangeRacng]

This topic has been gone over multiple times here. I'm sure if you use the SEARCH function, you'll come up with pages of replies. I will say what many have said before - each type of TUBING (not pipe) has it's place on certain types of trucks (PIPE has NO place on a truck). I am building mine out of DOM because it is stronger then regular mild, yet not as expensive as chromo (though it's close). Plus there is more work going into chromo (heat treating and crack chasing after use). My truck will be street driven and hopefully raced in MDR a couple times. I want it to last a long while, so I believ DOM is the best choice. Remember - chromo may be stronger, but is is more brittle and will crack not bend (as stated above), plus chromo fatigues more. Steve

[dunerking]

Thanks for the info hoek,I don't work in fab shop, nor do I think I work in one!I was just asking for some info so when I go to look for a new chassis it will be as safe as well as enjoyable.I was going to go with a Chenowth Genesis but wanted to know should I go with the chromoly or DOM? Thanks again hoek.Sorry for the rest you that got your panties in a bunch!Some of use don"t live out of a "fab" shop.

hit it hard

[boltonbros]

my cousins paid 5.00 a foot for moly in hawaii. i think when i go to buy moly for my truck i am going to go to cali and pick some up and ship it myself.

when in doubt throttle it out

[drtdevil93]

if i offended someone with my post, ill say this: i joke about every last thing in life, no matter how serious or important. ive attended way to many funerals for me to be uptight about everything. if you cant laugh about something, you shouldnt think about it.

as far as strengths go: i prefer chromoly. i dont have some simple roll bar that i call a cage. my entire cage is gusseted, ties in to the frame in about 14 places, and is all chromoly-MIG welded (a-arms are TIG'd). the only parts that arent chromoly are the bumpers. those are mild steel, to give a little bit of crumple zone. i have also beat the hell out of my truck for a year and a half now (it is a mdr 1450 truck), and have yet to find a single crack.
i have bent a few pieces of chromoly as well (lower a-arms). after flying in the air, and landing on the upside of a big ole whoop, the suspension bottomed out, and put a bend in my LCA. it didnt just crack anywhere on the arm, it just bent where all the pressure was.

as far as chromoly being illegal in nascar: so is square tubing, which is considerably stronger than round tubing. i could be wrong here, but i believe cart and irl cars both use aluminum chassis made of square tubing. how come no trophy trucks or class 1's use aluminum chassis? because it wouldnt work! its a completely different ballgame. along the same lines, whats best for a CORR truck, isnt necessarily whats best for a desert truck. one important difference is rocks. the desert is full of em, while CORR tracks arent.

now im gonna ask the most important question: Dave G. what is your opinion on the subject?

lastly, dont everyone get all upset because someone has a different opinion. its a discussion, not an argument. arguments are for those who can't think or communicate effectively.

erik

[BA_DirtDriver]

Wouldn't work? Aluminum chassis no problem just different design methodology. Here Fatigue would be much more of an issue not with chromoly. Why not Carbonfiber for that matter? Our sports expertise is still back in the tubing era. Which is probably where it will stay for quite some time as the requirements for field repairs necessitate materials with readily formable and fixable properties. While stiffer chassis are definetly the goal in design, the mode of failure is much more critical in off-road/desert racing. This fixability might be a consideration in the chromolly versus DOM mild steel, especially for the real bashers out there. What will the next generation Trophy Truck be made of? With desktop FEA availible to lots of people, can something radically different be far off? Will it break? Probably but eventually some new tech will take the podium and the rest will be scrambling to catch-up.
Just my .03

[fnkrngr]

So if chromomly is not needed for MY truck then would it be safe to say that DOM is ok for suspension parts? OR would the DOM's ability to "flex" not be acceptable in that area,since this is a prerunner and I dont need chromolly?

You dont know the looks i get with this truck on the east coast.

[apprentice]

I am a chassis fabrication student at Wyoming Technical Institue. Through the course of our education here at school we have covered this topic many times. We've been taught that the only reason why chromoly is allowed by different racing sanctioning bodies is due to weight savings. For example: If you were building a race car that had to meet a 4000lb. minimum wieght requirement, you could have the option of using 1.750x.120 DOM tubing or 1.75x.083 chromoloy. These two tubing diameters and wall thicknesses are extremely close to having the same strength. There are basically two schools of thought in some of the more mainstream types of racing, (roundy,round), by using the thinner wall thickness chromoly you could (A): Build the same chassis design that you would have out of DOM, and take the added weight savings that you gained, and strategically place the weight remainder requirement throughout the vehicle as ballast. This would be used for aid in cornering, suspension loading, weight distribution, etc..... Or (B): The second school of thought that takes the remaining weight savings and applies it throughout the car in the form of extra gussetting, x-members, framework. Aiding in resistance to torsional flex, overall tube chassis strength, etc......

Both these schools of thought have their own advantages, and disadvantages, and can only be decided by weighing the pros and cons of each. However if the choice to use chromoly is decided, their are some very serious fabrication elements to consider also. We have been taught that Chromoly MUST be TIG welded only!! The reason for this is due to it's inherent brittleness. TIG welding is a low deposition slow cooling weld, MIG is a high deposition, fast cooling brittle weld. MIG welding chromoly only intensifies the chromoly's tendancy to crack! I'l give you two examples; Take 4 pieces of steel, take two of them and tack them together with a MIG welder and allow the tack two cool, do not quench it to cool it off. Now put it into a vise and break the tack off. you will find that the weld tends to snap off. Now take your two other pieces and and tack weld them with a TIG welder, and allow to cool, then break that tack. You will notice two things, it will take you longer to break this tack, and it will try to bend the metal around it before it fails. For my second example, at the shop that I was apprenticing at before I left for Wyotech our fabricator Jack Bones (who has since passed away, to the great beer garden in the sky) did some frame mods to Jake Maness 2-1600 buggy. Jake has a chromoly frame, and I myself found about 6 cracks throughout it. Jack built a new rear engine cage for the buggy out of chromoly and MIG welded it together. Before the next race, while getting some testing time in on it, the engine cage broke at the MIG joints where it attached to the previous structure, again proving that chromoly must be TIG welded.

This brings me to my third point. TIG welding chromoly and properly stress relieving it will give you a strong joint that will absorb an impact. MIG welding chromoly will only intensify chromoly's brittleness, and leave it more prone to cracking and shearing at critical points.

When MIG welding mild steel, proper metal fit and prep is very important (cleaning steel of all mill scale/weld contaminants, and tight fit). When TIG welding chromomly, proper metal fit and prep is extremely critical! Thoroughly cleaning joints to be welded and leaving no gaps.

This is just my knowledge of the matter, and goes hand in hand with what I have been taught and seen. Take it for what it's worth. I know that personally I would trust a properly designed and welded EW cage over a MIG welded chromoly, or improperly stress relieved TIG welded chromoly cage any day!

Happiness is waking up to a job you love

[MNotary]

CART/IRL most upper level open wheel chassis is made of epoxy and some type of fabric.

The only place I have seen Aluminum chassis in a "race" vehicle is in Hill Climb (PIkes Peak).

[SpareChangeRacng]

I thought before (origional ?) we were just talking about material choice for the cage.

Maybe I should clarify a little more. I am using DOM for my frame and cage (all TIG welded). For my A-arms and 3 link arms - I will most likely be using chromoly, but of course it will be TIG wleded and heat treated/stress relieved. Steve

[Kritter]

According to that statement Lothringer Engineering who has been building numerous championship race chassis for several years out of Chromoly is all wrong becuase he Mig welds them together!!!! Our chassis is chromoly and it is mig welded and works excellent and every integral part is crack checked each race and so far we have not had crack propogation problems. The frame on the other hand has it's weaknesses and I would say that is a mild steel.

Kris
<A target="_blank" HREF=http://www.barneysprecision.com/fabproducts.htm> Fab Parts</A>

[AZmiik]

Well Kris all those airpane guys got it messed up to then. They had the nerve to Oxy-fuel weld the stuff. I am not sure but I would say landing an airplane puts just as much stress into a parts as anythings else and there are lots of CroMo airplanes out there. I am also not sure how a MIG weld cools faster than a TIG weld niether hae a slag coating that slows the cooling process as in SMAW. If your preheating like you should be and postheating there should be no brittleness in the weld joint. Or you could just OAW the joint and know that its going to turn out right in the end.

Mike

[hoeker]

when i researched my chassis, i found just as many fabricators addiment about mig welding chassis, as tig welding. either way can have problems if not done properly, my new chassis is mig welded, the reason i went this route is that i am pretty good with my mig, and am only a novice with tig. i am starting to tig some stuff and when i am comfortable with my ability i will tig my suspension parts. the greatest moly failures i have seen were tig welded chassis, but NHRA specs a tig welded chassis.

my old truck was all DOM with a lightweight moly front bumper. in the borg warner i t-boned a truck in turn one at about 50 mph. i thought sure my front bumper would be gone, or flat. my spotter told me it looked ok yet, so i kept racing. after the race we inspected it, and it was all bent to heck, but not one cracked weld. it was mig welded. that test alone was convincing enough for me that mig is good enough, if done properly.

<A target="_blank" HREF=http://www.rosshoek.com>www.rosshoek.com</A>

Some are born great, some achieve greatness,
and some have greatness thrust upon them.

[apprentice]

I wrote what we have been taught here at school, and we have been taught never to MIG weld chromoly. I am not an engineer and as far as I know there must be a MIG wire that is made for welding chromoly. I only know what I have been taught and what I have seen first hand. If there is a proper MIG process for welding chromoly, I would definitely like to learn more about it. My MIG welding skills are excellent, whereas my TIG is very good but still needs daily practice. So if you know more about a MIG process for chromoly, please elaborate, I'd be very interested to learn more.

Happiness is waking up to a job you love

[EQuin]

Sorry if this is somewhat off-topic, but being a newbie welder and fan of off-road racing I can't help but ask you experts. Why is square tubing banned in NASCAR? Why is round tubing (chromoly or DOM) preferred in desert racing vehicles, as opposed to square tubing? Is it because square tubing strength is based on a direct impact upon the flat face of one of its sides, thereby reducing its effectiveness in a roll or impact where the point of impact may not necessarily be upon its flat face?

By the way, I am having a ball soaking up all the great info on this thread! RDC and the rest of you guys rock!

Thanks for any extra info. Take care,


Ed Q.

[drtdevil93]

equin: yes, exactly. square tubing is much stronger than round, but only in when stress is in the correct plane, whereas round tubing is equally strong in all directions. Nascar banning square adn chromoly was probably a shortcut to thinking. their argument is that when the car crashes, it needs to give and collapse, or it will send to much force into the drivers body. i agree with this concept (how couldnt you), but chromoly could be made to do the same exact thing, at a lighter weight.

as for the mig-chromoly debate: first of all make sure we are all talking about normalized chromoly. normalized chromoly has been made so it isnt so brittle, it will either say 4130N, or 4130 cond. N.
this normalized chromoly has been made specifically to reduce the brittle tendecies of chromoly.

for the tig guys: are you using chromoly filler, or mild steel filler? if you are using chromoly filler, you MUST stress relieve!! the filler becomes much harder when welded. mild steel filler when welded becomes nearly the same strength as chromoly, making it acceptable. chromoly filler becomes much harder than the rest of the material, and becomes a very weak spot. the piece wont break at the HAZ, it will break right on the weld. and if you are tig welding with mild steel filler, there isnt much of a strength difference between this and mig welding (both use a mild steel filler metal).

erik

[EQuin]

OK, that's what I thought about the square tubing. As for the give and collapse argument, I guess that's similar to the crumple zone concept in today's modern cars, right? In other words, NASCAR prefers DOM round tubing because it's strong, but not so strong that it won't bend or help absorb the impact, thereby relieving some of the force of the impact that would otherwise transfer to the human body. Is that about right?

That's interesting what you say about the normalized chromoly. I have never heard of it until now. Is it more expensive than "regular", non-normalized chromoly? So an experienced fabricator and welder would do well TIG welding normalized chromoly with mild steel filler?

I'm just a newbie welder taking a MIG welding class at the local community college. I plan on sticking with MIG welding DOM round steel bumpers on my mostly stock, disco-ish, prerunner-wannabe Tacoma. But I enjoy reading through threads like this and learning all I can from you racers and fabricators.

Thanks for the informative reply, Erik! Take care and good luck at the races,


Ed Q.

[drtdevil93]

make no mistake, im very much a wannabe fabricator. i just hang out at with people that really know their stuff. most of my info comes from jesse and aj at the baja shop. i ask questions, and we all argue until we come to an agreement.

thats what nascar thinks, a chromoly chassis can do the same exact thing, and be lighter at the same time.

if the component isnt going to be stress relieved, and its to be tig'd, it should be done with mild steel filler, or it will crack severely(what ive heard at least).

BTW- interesting info. there are places out there that can stress relieve an entire vehicle. baja shop is taking their truggy chassis to one if a couple of days. 800 degrees for like 2 days!! apparently its some company that stress relieves crane components, or something like that, so they have a huge furnace. VERY low price.

erik

[jcorsico]

Just curious, but how much is that "very low" price for the 2 day heat treat? It would sure be a lot easier to weld the entire cage up, and then put the whole thing in an oven, rather than standing there with a torch heating up each joint one by one to stress relieve.

Jon

[drtdevil93]

dont know if they are getting some sick hookup on it, but they are paying $320.

erik

[Brian Mapes]

Everyone on this post is saying to tig weld chromo and then heat treat it but i read on this site that you should tig but not heat treat. Anyone know whats up?


http://www.tigdepot.com/faq.html

You gots to pay da cost to be da boss. - Snoop

[CRAIGHALL]

I THINK MOST,NOT ALL OF THE REPLIES WERE IN FAVOR OF STRESS-RELIEVING WERE'NT THEY?
THAT SITE ALSO RECOMMENDED STRESS RELIEVING JUST NOT THE SECOND PROCESS OF HEAT TREATING.

[hoeker]

not every one

Some are born great, some achieve greatness,
and some have greatness thrust upon them.

[Brian Mapes]

Sorry i didnt mean everyone, but it seams like the majority.

You gots to pay da cost to be da boss. - Snoop

[hoeker]

well, i suppose i'll elaborate a little. i have learned more elsewhere since this thread died. here's my .01$. 1st make sure you use cond N tube, then mig or tig, you decide, personally i think either are OK if done properly,and either can fail miserably if not. if you tig, tig with mild steel filler, if you tig with molly filler(not sure about the er80sd2), you must stress relieve. do not stress relieve the entire chassis, as you damage the properties of the parent steel, use the proper temp sticks (800 deg, i think), 1" from the weld and heat uniformally with a torch.

what'd i forget?

<A target="_blank" HREF=http://www.rosshoek.com>www.rosshoek.com</A>

Some are born great, some achieve greatness,
and some have greatness thrust upon them.

[Brian Mapes]

Thanks

You gots to pay da cost to be da boss. - Snoop

[motoxscott]

I'm curious why Baja Shop is heat treating their entire truggy chassis. Did they not do any temp. stress relieving? I've also heard through the grapevine not to heat treat an entire chassis.

-Scott

[drtdevil93]

not heat treating. stress relieving. you heat the whole thing equally and cool everything equally, so its all uniform.

erik

[hoeker]

according to the tig depot, and miller welds, this form of stress relieving is incorrect. are we sure that this is what they are doing at baja shop?? i heard bead blasting somewhere, not sure where?

just curious?

Some are born great, some achieve greatness,
and some have greatness thrust upon them.

[motoxscott]

Heat Treating = Treating the chassis with heat :)

I was refering to stress relieving the chassis with heat.

I heard they were putting it in an oven, not any kind of blasting/peening...... but it's just hear-say.

[bpthirteen]

Here is a page with some different terms

http://www.varcoheat.com/terms.html

http://www.prepbyjake.com

[ntsqd]

When you heat 4130 past a certain temp it changes phase from a relatively elastic phase to a brittle phase. If it is cooled too fast it will 'freeze' in this brittle phase. This results in a very strong, but very unforgiving and brittle HAZ metal. Normalizing, not heat treating, returns 4130 to the proper phase for our intended use.

There is no way any sort of shot blasting can change the phase of the metal to the elastic form. Shot blasting may mitigate the need to change the phase, that I do not know. I wouldn't trust my life to it.

Both TIG & MIG welding are high heat concentration welding technologies. They do not significantly heat the surrounding metal. This turns the surrounding metal into a quenching agent. So even if you're very careful about allowing the weld to cool in still air, you're still screwed. Oxy-fuel welding puts enough heat into the surrounding metal that is does not become a quenching agent. 4130 was originally alloyed specifically for welding with Oxy-fuel. Pre- and post heating are a solution, but how do you KNOW you got enough of the metal warm enough to not act as a quenching agent ?

Welding is on-site casting. Think about the actual weld process, compare it to what happens in casting metal and you'll agree. So a cage is bunch of cold worked steel (high internal strain energy) bonded together by a bunch of cast joints (low internal strain energy). Those cast joints suffer from all of the usual features of a casting. Wouldn't you want those joints to be as strong and elastic as the tubes thenselves ? I do.

Welding 4130 with mild steel filler results in a structure that has comparitively weak joints. The weld metal will pick up some of the 4130 alloying elements from the parent metal, but it won't become exactly the same alloy. Use a filler rod designed to yield the proper weld metal alloy and post welding Normalize it, or don't use 4130 in the first place.

TS

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