Is it necessary to anneal the weldjobs?

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I'm starting to build stuff like shelves, bed posts, scaffolds, etc. out of steel tubings.  I read on somewhere that annealing weld jobs is imperative for relieving stress.  I don't want anything to crack or snap off and hurt anyone.  Thoughts?
Reply:If your welds are sound, solid and defect free (no porosity or undercut), you will have no issues. You can forget about annealing. If your skills are not up to par to make a sound and defect free weld, annealing won't help you much.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:I think you mean stress relief? Most low alloy elements do not need street relief. As welded is sufficient.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Stress relieving or normalizing is something you do on very large weldments.  In  my career I have only seen one item sent out for stress relieving in a furnace then returned for final machining.  It was a base frame we made up out of heavy wide flange beams that supported a 100hp motor driving a huge roots type blower for a cement plant.  You are unlikely to have any critical weld stresses built up in weldments that weigh under five hundred pounds.
Reply:Are you building your stuff out of chrome-moly steel?
Reply:Originally Posted by KelvinAre you building your stuff out of chrome-moly steel?
Reply:Originally Posted by HelloStrangerNo, I don't think so.  Just mild steel.
Reply:Metals and How To Weld Them by James I Lincoln Foundation talks at length about the subject. The book explains that the stress of shrinking steel in a well designed weld will cause mating surfaces in crystalline structure to move carbon atoms to a void allowing a tighter bond between crystals. Slight stretching actually strengthens weld. They warn that very high tensile strength filler will not stretch as it cools, and may cause cracking in high strength steel.
Reply:In extremely cold weather, a bit of preheat won't hurt."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Originally Posted by OldendumIn extremely cold weather, a bit of preheat won't hurt.
Reply:Hate to do this in somebody else’s thread but…. would someone explain process annealing to me please… in layman’s terms so I can follow along with what he was asking and the replies.MM 211Smith Tru Lite O/A set, Thanks Bob!Lincoln AC-225--But you must not change one thing, one pebble, one grain of sand, until you know what good and evil will follow on that act. The world is in balance, in Equilibrium- Ursula K. Le Guin
Reply:Equi,The localized rapid heating (expansion) and cooling (contraction) involved with welding can cause internal stresses to build up in the weld and adjacent heat affected zone (HAZ) of the base metal.   Process annealing is a thermal treatment used to relieve these stresses (why it's also known as "stress relieving").   It involves heating the material back up to a certain temperature and holding it there long enough to let these internal stresses relax by letting the grain structure of the material reorganize it's self.  It's kind of analogous to how if your muscles are stiff and sore a good soak in a hot tub relaxes them.It's usually only necessary with some of the higher alloys used in more critical applications.  For the kinds of things the OP is talking about building (and the kinds of things you've been welding on) I can't see it ever being a factor that needs to be worried about.Last edited by HT2-4956; 12-01-2014 at 12:08 PM.
Reply:Process annealing is used to counteract the hardening effects of a cold-working operation on a metal. http://www.thermo-fusion.com/Annealing.html : Annealing and Stress Relief are terms used to describe heating a part to a certain temperature, holding it at that temperature, and then cooling the part at a relatively slow rate. Think of it this way: You’re stressed from a long day at work (the heat treat term is “work hardened”). You need to relieve the stress. Sitting in the easy chair and relaxing, that would be stress relief. But once you get up, there’s still the nagging pain in your back/leg/shoulder.Annealing gets rid of a lot more stress than a simple stress relief, and in many cases actually causes a softening of the material. You could say its equivalent to soaking in the hot tub or spa for awhile, then having a nice massage. A lot more of the nagging pain is gone.So, stress relief is a lower-temperature heat treating process that relieves some of the residual stresses, and cools the parts slowly so no new stresses are introduced. Annealing, on the other hand, is a higher temperature heat treating process that relieves a lot more stress and also softens the material."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Thank you. I have a basic knowledge of the damage rapid freeze/thaw cycling can do to things like ohhh... concrete patios and plants so what you say makes sense. So does this, "It's kind of analogous to how if your muscles are stiff and sore a good soak in a hot tub relaxes them" and this, "So, stress relief is a lower-temperature heat treating process that relieves some of the residual stresses, and cools the parts slowly so no new stresses are introduced. Annealing, on the other hand, is a higher temperature heat treating process that relieves a lot more stress and also softens the material." --I haven't been doing any structural welding and have no desire to do any but I was definitely curious about what he was asking... for future reference.  The welds I complete are checked to ensure they're functional. He used to find bad tacks and welds on my work all the time. Not so much any more and the last month I was welding.... I was spotting the flops on my own and grinding them out and starting over before he could walk back to inspect what I had worked on. It's real easy getting a non-functional weld when MIGing I've learned. For me at least it has been. Critical applications and any required annealing would best be left to the veterans.adding something...I found more on annealing, http://weldingweb.com/vbb/showthread.php...g-with-a-torchLast edited by Equilibrium; 12-01-2014 at 01:09 PM.Reason: adding something...MM 211Smith Tru Lite O/A set, Thanks Bob!Lincoln AC-225--But you must not change one thing, one pebble, one grain of sand, until you know what good and evil will follow on that act. The world is in balance, in Equilibrium- Ursula K. Le Guin
Reply:I have a customer who has all their weldments stress relieved prior to machining. Though they actually do this on aluminum weldments. The material is 6061-T6 because it is most readily available and they get it stress relieved to T0 to obtain certain mechanical properties for their application. Seems kinda hokey to me, but they've been doing this for decades. They also do it on their steel weldments because they experience cyclic loading (being repeatedly dropped or smashed into a wall, they build crash testing equipment), so in that case they relieve the stress to prevent cracking or breaking.John 3:16(2) Miller Pheonix 456(2) Millermertic 252Dynasty 210DXHobart 210MVPDoringer D350 SA Cold SawScotchman 350LT Cold SawWebb 10x50 MillWebb 15x40 LatheGeka Bendicrop Ironworker
Reply:Equilibrium;Weld filler is liquid, and hot expanded when it is put in place, as it cools a bit, it solidifies. As it cools the rest of the way, it shrinks. This phenomenon is most of what causes distortion in weldments. Weld two pieces of flat bar together end to end, the cross section is small, there isn't much distortion. Run a long bead of weld as joining two pieces of sheet metal edge to edge, distortion can be severe.I like the illustration of a crack in the cutting edge of a loader bucket. The weldor would v it out good making room for the filler to fully penetrate leaving a gap to fill. Weld it in with a very high tensile filler, it cools, the weldment is too strong to bend as the filler shrinks, enormous tension builds, the filler is very strong. BANG! The bucket material breaks beside the weld. If the weldor preheats the bucket using a big propane torch, giving extra attention to the area past the end of the crack, welds it in, then relieves stress by repeating the big torch heating process. it all shrinks together without much stress. In some cases very high strength filler isn't as strong as more ductile filler be.
Reply:Would you guys stress relieve this part before I machine it square? It is made of 1" thick 1018. I used 7018 rod. I built up a big fillet just to get some practice. Attached ImagesBrianMiller Thunderbolt 225 AC/DCEverlast 255 EXT with water coolerH.F. 170 Mig/Flux welderKent 3h.p. 9x42 milling machineHome Built 2"x72" variable speed 2 h.p. belt grinderHome built 9" variable speed 2 h.p. disc grinder
Reply:You better
Reply:melsdad,The stress relieving temperature for 1018 is in the 500 to 700 C. range (932 - 1292 F.).   And it's not just heating it up to that temperature and letting it cool slow.  Once you get it up to temperature you have to let it "soak" there for some time.   The general rule is one hour / inch of thickness.    It would be my guess though that it will machine up square (and stay that way) with out being stress relieved.
Reply:Originally Posted by HT2-4956melsdad,The stress relieving temperature for 1018 is in the 500 to 700 C. range (932 - 1292 F.).   And it's not just heating it up to that temperature and letting it cool slow.  Once you get it up to temperature you have to let it "soak" there for some time.   The general rule is one hour / inch of thickness.    It would be my guess though that it will machine up square (and stay that way) with out being stress relieved.
Reply:Some of the machining issues are when machining the welded area itself and one piece is effectively 'crushed' against the other."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Melsdad,This oven is capable of 1350 F.   It's computer controlled and is capable of a pretty precise heat treat profile.
Reply:IIRC, this batch of spool pieces got brought up to and then soaked for an hour at 950 F.  Then they were allowed to cool at a rate of 75 degrees / hour until they got to 600 F.  At this point the oven was shut off and they were allowed to cool the rest of the way over night in a closed oven.   When the oven was opened the next day they were still close to at least 300 F.
Reply:Here's some more stress relieving of pipe welds on assemblies that were to big to fit in the oven.   This is a good example of how they use electrical resisitance heating to stress relieve pipe welds in the field.   A big part of my job for the last 3 years has to been to build the controllers and maintain the equipment for doing this.
Reply:Stress relieving is simply heating to a certain temp below the critical and holding it there long enough to reduce residual stresses and cooled slowly to to minimize new stresses. Stress relieving is not normalizing or annealing which are done at higher temps.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720Stress relieving is just another term for "process annealing".   You are correct in that it does occur (is done) below the lower critical transformation temperature (Ac1).   Full annealing (maximum softening) on the other hand requires that the material be heated above it's upper critical temperature (Ac3).   Even though stress relieving (process annealing) occurs at a lower temperature than "full annealing", time at temperature is much more important to stress relieving (process annealing)than it is to "full annealing".
Reply:This is the furnace I used for this part. If it were a critical part I would have used computer controlled furnace to control the step down from the soak temperature. I brought the temperature up to 1200 deg. And let soak for 3 hrs. Then simply shut it down and let it slow cool in the furnace.  After 26 hours it is at 300 deg. Attached ImagesBrianMiller Thunderbolt 225 AC/DCEverlast 255 EXT with water coolerH.F. 170 Mig/Flux welderKent 3h.p. 9x42 milling machineHome Built 2"x72" variable speed 2 h.p. belt grinderHome built 9" variable speed 2 h.p. disc grinder
Reply:Damn these sideways pictures! Never had a problem till tapatalk did an upgrade. How do I edit this to make the pictures right?BrianMiller Thunderbolt 225 AC/DCEverlast 255 EXT with water coolerH.F. 170 Mig/Flux welderKent 3h.p. 9x42 milling machineHome Built 2"x72" variable speed 2 h.p. belt grinderHome built 9" variable speed 2 h.p. disc grinder
Reply:Brian,There's nothing wrong with that oven for doing what you did with it.   Stress relieving a 1018 weldment like what you built is a pretty straight forward operation with out all those critical hold points and rates of heating and cooling like there would be with something like p22 or p91 group piping materials.   With the heat profile you say you subjected the part to I'd have to say it's probably well stress relieved.
Reply:Here is the part out of the furnace after 30 hours. I'm going to sandblast the scale off. Then machine it square a nd surface grind it. Hopefully I'll have this complete in the next week or so. Attached ImagesBrianMiller Thunderbolt 225 AC/DCEverlast 255 EXT with water coolerH.F. 170 Mig/Flux welderKent 3h.p. 9x42 milling machineHome Built 2"x72" variable speed 2 h.p. belt grinderHome built 9" variable speed 2 h.p. disc grinder
Reply:Angle plate for the mill?
Reply:Originally Posted by EcondronAngle plate for the mill?
Reply:All machined square and ready to be surface ground. Attached ImagesBrianMiller Thunderbolt 225 AC/DCEverlast 255 EXT with water coolerH.F. 170 Mig/Flux welderKent 3h.p. 9x42 milling machineHome Built 2"x72" variable speed 2 h.p. belt grinderHome built 9" variable speed 2 h.p. disc grinder