After welding 4130 tubing (for a roll cage), I know a guy, (a very reputable guy) who is dousing it with WD-40. I know you are supposed to anneal a 4130 joint but what does the WD-40 do? He does not anneal the tubing after spraying with WD-40. This is the only treatment the joints get and it works very well. Anyone seen this before?
Can you define what you mean by "works very well"? Does this mean the welds perform in typical weld procedure qualification tests like they do if they are heat treated? I suspect the WD-40 does almost nothing at all. The thin fluid film could accelerate the weld cooling rate if he is spraying a lot of it directly on the weld immediately after welding. The result would be something similar to an oil quench, but it would have to be a lot of fluid and a thin tube that has little mass to hold much heat, and it would not be very reproducible because of variations in time between welding and spraying and the volume of fluid used. If the fluid had any effect it would be to promote, rather than retard the formation or hard, low toughness microstructures in the heat affected zone. It just sounds odd to me.
4130 is an air-hardening steel alloy. Quenching it with water or oil tends to induce cracks in the welds. Are you sure that the "dousing" this guy does consists of quenching the hot welds? Perhaps he is coating the interiors of the cooled, welded-up tubing assemblies with WD-40. Filling a 4130 tube fuselage with oil (or special tube oil), for example, and then letting the excess drain out is common practice among aircraft builders.
define "reputable" please.
Who says you have to anneal? PWHT depends on desired results. Not all PWHT is done with heat. There is peening, vibrating, cryogenics and now WD-40ing.
You didn't say how long after weld this operation occours. Does the WD-40 ignite and generate heat from the flames? I wander how much Hydogen is in the WD-40.
my guess is the WD-40 is just to prevent scale and rust.
The guy builds race cars for a living...winning, race cars at that. I've seen these cars time and time again, flip corner over corner at high speeds (70+mph) and they hold up very well. The welds don't break apart, the tubes don't crack, the car holds up like it is supposed to. As a matter of fact, the most recent one held up so well that it only needed minimal repair. It sounds odd to me too, but i've seen guys that don't know what they are doing build a chassis or roll cage, have it flip a couple times and it just breaks apart. As far as I know, as soon as he's done welding, he sprays it down and that's it.
The post weld heat treat debate on chrome molly tube (especially thin cluster joints) will rage on until the good Lord comes with a shout and the great heat treatment takes place. You can do a google search on 4130 aircraft welding and hear as many opinions as there are stars in the sky, this includes major componant manufacturer standard practices, not just barn stormers.
Why are you asking us why the guy sprays the penetrating oil? Why not just ask him why he does it.
My side bet is that the guy sprays the stuff on as a corossion preventative until paint prep takes place.
Why not ask here, it is a welding forum. Why wouldnt' you want me to post this question here? It was something new, something I didn't find in my most creative of web searches. It's a race shop, the guy builds race cars. This isn't the type of thing that a guy would share with the world and I'm not a personal friend of his, otherwise I would know and I wouldn't post it here or anywhere for that matter.
The reason I'm asking is that if one can get around annealing each and every joint, the work would be cleaner and take far less time...maybe 10 minutes a joint in time savings. It is not for corrosion as nothing he builds gets painted...ever.
Keep in mind that WD-40 is not a penatrant nor is it a lubricant. It is a water dispersant (WD). It is probably the most abused and mis-marketed chemical we keep in our garages. If your buddy is using it for rust protection, there are much better materials to use.
-Ben
Oops, Diddn't really mean to sound so flippant, sorry about that. Asking here is great and your question is a good one. But I think the only person who can really answer it is the guy with the spray can <g>.
Fact is that if the weld is freshly made <real hot> than spraying WD on the thing can only make it brittle and can never make it more ductile. Maybe its a little trick he plays on folks who he thinks might be lookin too closely at his fab practices. A Red Herring? I've helped build custom race cars and airplanes and never has speed been a factor to be worried about, so I doubt time savings plays into it.
Try a little destructive test and see which breaks easier; with or without a WD-40 bath. I weld 4130 tubing daily and have not heard of this technique. Doesn't mean it can't be of some benefit, though. Good luck, Scott.
I'd hazard a guess and say it's only for rust prevention. The heat affected area quickly forms a surface rust and even more so in a humid enviroment. We build sprintcars with 4130 and we will spray & wipe WD40 over the chassis to prevent the onset of surface rust. Some guys don't even have their chassis painted or powder coated just simply give it a wipe down with WD 40 after every race meeting. We like it when the guys do this because in the repairs it is much easier if we don't have to remove any paint or powder coat.
Regards Andrew.
My bet is on Andrew's answer! Sounds very reasonable and makes a lot of sense.
John Wright
People pay a lot of money for racing chassis and they like them to look good (can't blame them). I'll bet the WD-40 is just a rust preventative applied after welding and cleaning is done.
Chet Guilfor
My chassis is excellent because I douse it daily with WD. I'm not sure if I'm any shinier, but my joints sure don't creak...anyway, it is not for annealing purposes.
Regards,
Vonash
And what kind of chassis are you talking about? Never mind! Don't need to know!
JW,
I'm confused about it all.
When that WD was applied did it smoke and vaporize? We don't really know, but I'd doubt he'd be trying to [anneal] the steel once it's become "cold", do you think? I've used WD as a coolant when I didn't want to cause surface rust with water... it made a really nice mess and the rust it prevented would have been easier to clean.
Be aware, everyone, that regular inhalation of oil mists cause long term health hazards, though.
off topic- regular bleach is a slippery-er product than most oils.
I submit that a lubricant is as a lubricant does, and that WD does poorly to protect against friction... I suspect the molecule's property that gives it the ability to penetrate is the same property that prevents it from being an ideal lubricant.
off-off topic- we've used WD40 as a means of (unofficially) testing air quality alarms used to alert us of chemical attack; I suspect it's base penetrates and is absorbed very well into the skin- it's kind of scary to think of Vonash lubing his chassis every night, or many of us with our hands in it regularly without really knowing what it does to skin cells and body chemistry. (...just kiddin V)
regards
d
Here's what I think since no one else has heard of it. Why spray the WD40 on it? Probably not for any reason that will change the properties of the material. I think this guy just falls into the "You don't have to anneal it when you MIG weld it" category. After some searching on the net, I've found out that some agree and some disagree with this method. Citabria aircraft, for example, MIG welds their plane chassis and they do not anneal it. They say the FAA tests their welds and are happy with Rc 38-41 in the weld. The tubing will test about Rc 3 next to the weld while the same tubing next to a gas weld will test almost zero. FYI - Most sources say a piece of 4130N tubing will test Rc 19-23 before welding. One stipulation was that the material needed to be very clean to avoid hydrogen embrittlement.
All OEM airframes are wirefeed welded and none that I have heard of are PWHT. Robinson Helicopter may be the exception; I did here that they PWHT in an oven big enough for the entire weldment$$$. Helicopters are more suseptible to vibration and harmonics, and they sell them in spite of the added expense. 4130 tubing is very forgiving; I have seen lots of very bad welds and they (almost) never break.
Just to try and keep everyone on the same page here:
Definitions are from Jefferson's welding encyclopedia
Annealing: A treatment or process in which a material in the solid state is heated, then cooled at a slow rate.
Quenching: The sudden cooling of heated metal by immersion in oil, water, or some other liquid medium, a molten salt, or by spraying with a jet of water or compressed air. The purpose of quenching is to produce desired weld strength properties in hardenable steel.
Therefore, the WD-40 would not be for annealing, as it is not insulation to aid in slow cooling. It could be for quenching, but is most likely there to prevent corrosion.
Forum
