Dipping hot weld joints in water

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At the student forumula one lab at school, I keep seeing people weld up parts, and then run to the sink to douse the parts in a bucket of water.I've always been told this is one of the worst things you can do, but I never had any reasoning behind it.And as you may have guessed, many of these parts are suspension and steering related.What's a good argument to get these crackheads to quit it?
Reply:Just ask them casually to sign here, and slip em a release form for a life insurance policy.  The reasoning behind it is it makes the weld and surrounding HAZ brittle in addition to causing the weld to contract and possibly crack from rapid cooling.  Youre right it is a big time no no, especially on suspension/steering or critical components.  I personally would not ride in anything that had been welded to fix the steering and I would be very wary of suspension welds.  I also wont weld those items either, so I am not being a prima donna just limiting my liability to me and my family.  You would be well advised to look carefully before you leap into that pond, the gator can eat you up quick... HTH.BobI'm spending my Kids inheritance, I dont like him that much anyway!!!!!!Enuff tools to do the job, enough sense to use em.Anybody got a spare set of kidneys?  Trade?
Reply:Here's a pretty good example if you will....At work we use what we call spacing tools.  On the pipeline we drive them between the bevels of two joints of pipe to get the necessary space between them.  Some of these spacing tools are home made from a piece of normal car leaf spring (model A springs are supposed to be the best, so is Samurai 4x4 springs).  While making or even after normal use these spacing tools need to be resharpened and that is normally done by using a grinder and a typical grinding wheel.  During this grinding operation (resharpening) these spacing tools get very hot especially at the tip where its very thin.  If you allow the tool to get hot the material tends to loose its hardness.  The hotter you let it get the quicker the hardness of the material goes away.One good way to retain the hardness of the spring material these tools are made from is to limit how much grinding you do between dipping it in water to cool it.  You don't want to get it hot enough to sizzle when you wet it down, but rather wet it often enough, grind it lightly enough, so the material remains very cool thus keeping the hardness that tools like these need.Once a tool has been heated to excess and becomes soft (not hard anymore) there is a way to replace some of the hardness and that is by heating the spacing tool either by sharpening it with a grinder or even heat it by using a propane torch up to nearly a blue color.  If it turns blue its too hot.  Then dip it instantly in water and let it cool quickly.  Done even only one time a soft tool will be noticeably harder.  Done more than once and you can again tell that it gets harder with each treatment.  The metal will be far more brittle than it was when it was a spring but sometimes the only quick fix for an improperly sharpened spacing tool that was allowed to get to hot and became soft.Good luck.
Reply:So long as they are welding mild steel it is technically fine. This is because there is not enough carbon in mild steel to harden. Getting into higher carbon, tool, or spring steels is another thing entirely. The problem comes about primarily with A-36 steel. This is the most available and cheapest steel. It is made to a guaranteed MINIMUM tensile strength, that means it can be higher/harder/tougher than normal and still meet the minimum specs for A-36. It is almost all remelt. I have found unmelted ball bearings in it, and have also been punching a length only to have the ironworker stall out on a hole in the middle. So it can have higher carbon, or hardenable spots in it. To avoid this use cold rolled steel, which is made to a guaranteed carbon content instead. Now if I were making myself axle brackets or spring perches, or steering parts would I quench them after welding? Heck no, why run the risk. Have some patience, and wear gloves, so that you don't have to quench it in order to handle it.
Reply:When you heat and cool metal you change the molecular crystaline struture... and the changes the hardness/makes it more brittle.Also carbon in metal can be gained/released when you heat a metal changing its hardness and maleability.Either way don't do that **** unless you are doing it for good reason... and student formula 1, are you talking about Formula SAE?
Reply:Yes, FSAE. Most of the stuff is 4130
Reply:If you want to know what happens when medium to high carbon steel is heated and cooled you need to do some research on quenching, tempering and annealing.Quenching is the heating of med. to high carbon steel above the critical temperature for steel and then immersing it in water which makes the steel very hard and brittle.Tempering is the reheating of med. to high carbon steel after quenching to a specific temperature below the critical temperature which softens and toughens the steel depending on  its intended use, ie files, springs, chisels, etc.Annealing is the heating of steel above the critical temperature and allowing it to cool very slowly which will make it soft and workable.Your ordinary mild steel does not have enough carbon in it to harden by heating and quenching."The reason we are here is that we are not all there"SA 200Idealarc TM 300 300MM 200MM 25130a SpoolgunPrecision Tig 375Invertec V350 ProSC-32 CS 12 Wire FeederOxweld/Purox O/AArcAirHypertherm Powermax 85LN25
Reply:Originally Posted by noriteAnnealing is the heating of steel above the critical temperature and allowing it to cool very slowly which will make it soft and workable.
Reply:I make knives just for fun out of leaf spring steel (I even put together a belt grinder to grind bevels and profile the blades) so I am familiar with the quenching, tempering and normalizing proceses, at least in their rudest way.After quenching our blades (bring to red hot, then dunk in warm motor oil) if you happened to drop them to the flor, they will probably shatter in pieces. Just like if you dropped a file (btw, we also use old worn out files for this). If instead of cooling them so fast you just let them stay between the ashes of the fire or cover them in vermiculita (or any other kind of insulation), the steel becomes soft and pliable.We usually follow a tempering process after quenching our blades to draw a few RC grades out of the steel so they are not brittle but still maintain a fine edge for a long time.If we bring this to the welding world, if you happen to cool a weld to fast (dunking in water), it could become brittle depending on carbon content. Just as they other forum members told you. On the other hand, if you let them cool on their own, chances are scarce. If you were to build something critical, the proper way will be to weld and then normalize the whole thing. You could even get it heat treated to certain specs.I hope this helps,Mikel
Reply:I almost didn't write anything to this post.......but something has to be said. You are a group of people that are supossed to be "engineering" students. If you cannot find any information at your disposal about basic metalurgy in an engineering school, that's scary and your school should be ashamed. Who is your technical advisor anyway? Seriously this is pretty pathetic. I see lots of FASE teams, and more and more the teams are so facinated with their latest design software and CNC machining center, that they are not learning all the basics of materials properties. So go to your school's library, check out volume 6 of the ASM handbook and READ! Then, armed with this "new" information that has been around for 100 years, you can proudly tell your fellow collegiate that they have been doing material harm to the parts of their precious overpriced go-kart, and it's a shame that the 3D modeling and FEA software didn't catch that for them.
Reply:Originally Posted by TaidenAt the student forumula one lab at school, I keep seeing people weld up parts, and then run to the sink to douse the parts in a bucket of water.What's a good argument to get these crackheads to quit it?
Reply:I'm trying to break out of the current mold of engineering students by asking you wise old timers where to start with this. No one ever teaches us where to find this information, so I decided to go directly to the source of intrinsic metallurgy and welding knowledge that is the members of weldingweb.comI will check out chapter 6 of the ASM handbook. Thanks for this tip. Gives me an excellent place to start.I am familiar with quenching, tempering, and annealing, but only enough to scratch the surface.
Reply:[QUOTE=Taiden;556273]I'm trying to break out of the current mold of engineering students by asking you wise old timers where to start with this. QUOTE]You don't have to be old to be wise or knowledgeable, age just has given someone more time to learn, doesn't mean they have used it for that though. Talk to your materials science prof and get some books from them. You are not alone amongst most young engineering types I have to deal with. One of the biggest shortfalls in our education system is that we don't teach people how to research. We think we teach them, but we don't. I am constantly having to dig up information for fellow engineers that they can't seem to find. These are people in their 30's and 20's and are under the impression that if it cannot be found in under 30 seconds using Google, then the information does not exist. And these are professionals!  Engineering librarys are great, use them, do not be affraid of a dusty old book.
Reply:OMG a BOOK ,,,, that means ya have to open and turn pages.. whats this world coming to .. half the fun is reseach, still some old school processes work fineidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:Last time I moved it took 2 trips with a pickup to move my books. But thier are alot of things you cant learn by reading a book.Taiden your advisor should have saw this and said some thing about it.Some times you have to run somthing in the ground to find what your looking for.
Reply:Originally Posted by Old DougLast time I moved it took 2 trips with a pickup to move my books. But thier are alot of things you cant learn by reading a book.Taiden your advisor should have saw this and said some thing about it.Some times you have to run somthing in the ground to find what your looking for.
Reply:Well, something I found strange, was that at my community college we would run beads on coupons and then dunk them in water. I mean, for coupons where you're running stringers all day, it doesn't really matter. I just always wondered how many guys got into that habit after they left the program.As far as books go, I couldn't agree more. The current trend for university library's is to order licences to electronic texts, which in a lot of ways is harder to find. Can't just whip out the breakdown of the dewy decimal system and find what you need. You have to go around looking by title, which a lot of times can be totally convoluted.I wish computers didn't even exist, except for scientific calculators. Being able to share information is truly amazing, but it creates a certain level of ignorance for things that are published in cold hard ink.
Reply:Originally Posted by TaidenI'm trying to break out of the current mold of engineering students by asking you wise old timers where to start with this. No one ever teaches us where to find this information,.
Reply:lol soooo ture  my Dad use to call those book smart Porfs " educated morons" no real world training -- some can't pour p!ss out of a boot,  with instructions on the heelidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:Originally Posted by prop-doctorlol soooo ture  my Dad use to call those book smart Porfs " educated morons" no real world training -- some can't pour p!ss out of a boot,  with instructions on the heel
Reply:Saw an inspector yesterday take his empty coffee cut, fill it with water and pour it on the cooling weld repair because he did not want to wait for it to cool naturally.  He had to do a UT on the repair.  Go figure!!
Reply:Well, it's a real and obvious problem in engineering curriculum.  Most of the students are fresh from high school, and you don't know what you don't know.  Very few new engineering students had any welding background in high school at all.  Probably never seen a weld.  I know I didn't.  The thing that the professors are missing is that there is a huge opportunity to teach something valuable here.  Not everyone needs to be a great welder, but if you are a ME you should have a passing knowledge of what it involves.  Some more so than others, depending on what they go into.  Now also realize that the profs are PhDs and that means they are the Ubergeeks.  In ME, very few get a PhD, so those that do tend to be the real esoteric guys. This is not a match made in heaven for the real world ME engineer as those profs also "don't know what they don't know".  Best thing you can do is have someone with a clue that teaches the group what needs to be done, but that person is not always there.  And if it is a student in this role, there is the issue that they will be gone shortly too. So like most things in life, it depends on the individuals involved.  More real world would be nice in school, but it rarely happens.  Sadly.  Some get it.  Some do it.  Most end up finding out what they don't know on the job and learning there.-DaveXMT304 with: 22A Feeder, or HF251 Hi Freq DC TIG air cooled
Reply:Originally Posted by davecSo like most things in life, it depends on the individuals involved.  More real world would be nice in school, but it rarely happens.  Sadly.  Some get it.  Some do it.  Most end up finding out what they don't know on the job and learning there.
Reply:Originally Posted by 4sfedYou've just made a good argument for co-op programs.