Conclusions...

admin

I had read this quote in the General Welding Questions Forum this A.M. ...Cold rolled steel doesn't bend well at all. It is work hardened material. If you take a piece of 1/4 cold rolled flat bar and even bend it with a one inch inside radius, it will more than likely crack or even break.
Reply:I always thought cold worked was the material of choice for cold forming.  I've never seen someone take an english wheel or hammer and sand bag to a piece of hot rolled steel.  I've never seen hot rolled tubing go through a tubing bender, either.
Reply:I don't konw... I will say that in the past I have seen (with my own eyes) cold rolled develope small tears at each edge of the plate, along the line of the break tool. I have never seen it break like I have AR but there again it could have to do with the grain of the material..... again people have to understand that steel has a grain just like a piece fo wood does. Picture it like this.... If you take a plank, say 1" x 12" x 12" with the grain running the place it over a sharp corner  so that the corner runs across the grain. Push on both edges and try to break it. It probably won't break. Now turn the plank so the corner runs with the grain and do the same thing, pushing the same way.... It will probably break and faily clean, right on the grain line. This could very well be what I was seeing._________________Chris
Reply:Is there a easy way to tell the direction of the grain?Various GrindersVictor Journeyman torch200cf Acet. 250cf oxygenLincoln 175 plus/alpha2 gunLincoln v205t tigLincoln 350mpEsab 650 plasmaWhen you can get up in the morning, Its a good day.Live each day like its your last.
Reply:The direction of the grain follows the direction of rolling... and is parallel to edges of the sheet or bar.To bend across the grain is to bend at right angles to the direction of rolling.To bend with the grain is to bend parallel to the direction of rolling. In steel, the  ductility in the direction of rolling is almost twice that at right angles to the direction of rolling._________________Chris
Reply:Originally Posted by lorenzo.... again people have to understand that steel has a grain just like a piece fo wood does.
Reply:Doesn't hot rolled steel have a lot of inclusions in the surface that would make it more prone to cracking during a bend?
Reply:Zap and Graham.....Thank you both.....Graham, I anxiously await your next few posts.Patrick
Reply:Re reading my post I realize I made a mistake in how I worded my comparison  with regard to the grain of both wood and steel.What I meant to say was steel has a grian, AS DOES a piece of wood.Before I start a landslide of crap.... let me say that I used wood as a general aid that most people can quickly connect with because, most of the people here probably understand grain as it relates to wood. I'm sure that are also plenty of people, such as yourself, who understand it in the true sense as it relates to the crystal structures. I was just assuming that some of the folks who would read this may have at some point  broken a small board in the manner I mentioned, which may help them visualize what I'm talking about. I'm strictly relating grain to the bending/ forming of steel. As to identifying the grian direction......... from what I have read and have been told.  The relation of the direction of the grain is as I've described.I'm sure I'm going to get educated at this point so I'm ready._________________Chris
Reply:It is not a grain direction but size of the grain and the grain boundary among other things that determines the strength of metals.I have to reach back 25 years in my mind for some of this info from my under grad engineering days...I am am electrical engineer now.Graham will/can come back with more info that your head will be spinning. My best friend is a mechanical engineer that investigates metal fatigue failures in aircraft...very fascinating."Common sense is not very common"http://www.tahoekeyshome.com
Reply:[QUOTE=grahamtheengineer]Not a correct statementGraham :  If you look up in texts that are contemporary to someone like myself I think you will find the term grain commonly used. This was when a electron microscope was but a dream.  I was confused as instructors would babble on about grain and crystals.  The definition that I found was that a grain is an imperfect crystal.   Hmmm  I looked through my old texts:  I guess dendritic, equiaxed and elongated grains don't exist any more.  Global warming must have caused it.   I still see instructions on prints for forming plate and there will be notations with arrows indicating required "grain direction" in the plate.   Also in shops often there are instructions to note the grain direction on all crop plates before returning to stock.  I'm just an old guy making some "old " comments.
Reply:Originally Posted by brucebIt is not a grain direction but size of the grain and the grain boundary among other things that determines the strength of metals.
Reply:Zapster -- I like your approach -- just try it and see what happens.  Nothing more revealing than an experiment.  Many if not most of human discovery is driven by experimentation.  It worked for Thomas Edison!  Great stuff. DISCLAIMER: yes, yes, if safety or codes are involved we need solid engineering -- but a lot of times the only way to learn first hand is to experiment, as long as there's no danger of somebody getting hurt if the experiment "fails."  I like the analogy of metal having a grain as does wood -- easy for me to understand and I also look forward to Graham giving more details of what's really going on.  I'm seated in class at WeldingWeb college.
Reply:The first piece is 1018 cold rolled steel, 1/4 x 1.0 and the other piece is 1/4 x  3/4 A36 bent on a craft bender against a 3/8 dia. pin.  Every metal company I have ever bought cold rolled from asked me if I was going to bend the stuff because they don't like people to bring back broken pieces and claim the metal was bad.  I would never trust my life to  a piece bent cold.  However, if you heat the area red hot where the bend is to take place, it is safe to bend even after it cools. Attached Images
Reply:Looks like I have more mad scientist experiments to do tomorrow.. ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by 76GMC1500I always thought cold worked was the material of choice for cold forming.  I've never seen someone take an english wheel or hammer and sand bag to a piece of hot rolled steel.  I've never seen hot rolled tubing go through a tubing bender, either.
Reply:This is exactly everyone here learns something new everyday..I love this place!! ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by lotechman  Lamellar tearing is common in large plate if the weld is located in the wrong place.  Here we go again: Imagine edge gluing two boards together as you would do for a table top or cutting board.  When you break it the glue line holds and board breaks along it grain.  A similar thing can happen when large welds shrink and tear the grain in the steel.  A weld placed ninety degrees to this would not suffer the same fate.  I could be confusing ductility differences however.
Reply:Originally Posted by lotechman I could be confusing ductility differences however.
Reply:look at the topic "minimum bend radius"http://www.ottawaproducts.com/produc...0BEND%20RADIUS
Reply:"GRAIN""A solid polyhedral (or many sided crystal) consisting of groups of atoms bound together in a regular geometric pattern. In mill practice grains are usually studied only as they appear in one plane. (1) Direction of: Refers to grain fiber following the direction of rolling and parallel to edges of strip or sheets. (2) To bend across the grain is to bend at right angles to the direction of rolling. (3) To bend with the grain is to bend parallel to the direction of rolling. In steel, the ductility in the direction of rolling is almost twice that at right angles to the direction of rolling."http://www.metal-mart.com/Dictionary/dictletg.htm#I7
Reply:Lets add some Acetone to the fire!!!Reading over this thread..I love this place!! Ok now here are some pics from this afternoon..1/4"X2" Cold Rolled flat stock..Dirty yes but thats not the point here.. Subject..The only way to bend this was with a really big adjustable wrench and me hanging off the ground...I tried the hammer deal ..No way..My hands could not take the shock of the hit..So don't do it.. But anyways..Its bending...Now thats pretty bent..I see no signs of fatigue..So I dunno..This what it is and thats what I have come up with..I'll try more if needed..thats no problem.. But check this out..I don't know how I did it but thats pretty cool.. ...zap! Attached ImagesI am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Is that my shirt hanging from he machine? _________________Chris
Reply:YUP ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Hey Zap is it possilbe that your bends aren't with the grain ? And if you were to try to bend it the other way which would possibly be with the grain it would crack and break. Because I have seen metal develop a tear when bent to far or the wrong way Im guessing.Will   Supports Autism Awareness                            My ToysBobCat 225 PLusMillermatic 130Miller Spectrum 300 CutmateEverlast Power Tig 185 Micro April is Autism Month .When making a bend in any material, a small radius will be more stressfull than a larger one.  If you form a 90 degree bend with a 3/8 bend radius in a piece of 1/4 x 1.0 cold rolled steel flat as it comes from the steel distributor, the amount of material from where the bend starts to where it stops is about .75 inch.  What you are doing is concentrating all your force in that small area.  Commercial cold rolled flat I am talking about has a tensile strength of about 85000 lb. per square inch.  Cold rolled steel starts out as hot rolled steel and goes through pickle process and then is run through rollers cold.  The more it is cold worked, the stronger it gets.  What you gain in strength is lost in bendability.  So if you want to do an accurate experiment, bend your metal in some sort of bender, (press brake, hossfeld, shop outfitters, harbor freight.) I believe most commercial 1/4 cold rolled flat is full work hardened material.
Reply:Nice job zap!!...but look at the size of the radius you bent that piece to. If you were to have bent that to a hard 90*, it would crack and break. (like Riley's pics)Materials have a minimum bend radius...(look at the link that Dipper posted.)Just like bending tubing for a roll cage. There is only so tight of a bend you can put in a tube (or plate for this matter) without causing failure. Usually it's 1.5 times the diameter or thickness of the material.The outside of the bend has to stretch farther than the inside and causes deformation of the material taking it beyond it's yield point.I'll bend some cold rolled to a hard 90* in my 10' brake later today and post a pic of it....it won't be pretty.  - Paulhttp://all-a-cart.comWelding Cart Kits and accessories
Reply:Wheres mr. spock when you need him eh?Various GrindersVictor Journeyman torch200cf Acet. 250cf oxygenLincoln 175 plus/alpha2 gunLincoln v205t tigLincoln 350mpEsab 650 plasmaWhen you can get up in the morning, Its a good day.Live each day like its your last.