you can, even rivets, though you need the equivalent amount of them and making the holes and installing them require more work and time..
Sometimes you also can't, depending on the purpose or placement
I see you don't know shit about welding. Most weld alloys are stronger than the base metal to begin with. Now, try to visualise the welded work as if it had been made from a single piece of metal bent in that shape. The fillet is about as thick as the metal itself.
>Most weld alloys are stronger than the base metal to begin with.
So what? Yes its a stronger metal but its still covering only a small percentage of the area.
>Compared to what? Butt joints?
In the sense that the bulk of the metal isnt contributing to any strength. It may in some cases only
7 months ago
Anonymous
How so? It's welded twice (lower rate of failure) and it's double the thickness for some span, so it has twice the bending resistance at the lap. The lap is not fused over the entire area but it does not matter the slightest bit.
When you're welding a corner angle, you leave the fillet there because it's not in the way and it would be extra work to take it off, but if you had complete penetration of the joint, you could grind away pretty much all of the fillet and it would hold just fine, as if you had put a bend in a single piece.
Why are butt weld much harder? Is it because you have to bevel them and fill that groove with more passes?
>What does it matter if the weld only penetrates 0.1 mm if you still get fusion of the material?
More deeper penetration means more metal is fused which means a stronger weld. For example the thing you're welding might be expected to go through heat cycles during use. If you have trapped non-welded gaps they might have gases or liquids inside that expand and contract during the heat cycle, putting strain on the weld from within that eventually causes the weld to fail due to mechanical stresses while metal is weaker when it is hotter and wants to contract and expand on its own while heating up and cooling down. Same if its going through pressure cycles. In lots of applications the way you fix the issue of penetration is by removing large amounts of base metal and fill it up, then you do various tests to make sure its completely solid and if its not you grind those parts up and fill it back with weld again. I'm sure there's cases where you can do lap joints for pressure vessels but the butt joints are stronger simply because they don't have any gaps in them at all.
How does one make sure that a critical weld has what it takes? Im concerned about the weld being brittle, cant you make it pliable by heating it and letting it cool slowly?
Can welded material be forged? I say it because these butt welds always curve, is it possible to heat them red hot and bend them into shape?
>Why are butt weld much harder? Is it because you have to bevel them and fill that groove with more passes?
Yes but there's way more to it than that. On the root pass you're constantly walking a balance with the heat of the puddle because too little and you don't get proper fusion but too much and you overheat the puddle and burn a giant hole in the joint with white hot metal and slag falling off, hitting the floor and splashing all around you. On the first fill pass you can even get too hot and end up doing a second root pass which fails the joint, while still dealing with the issue that you might burn a hole into the joint like before. In theory its same stuff you do on other joints but with butt joints you simply have less room for error. You need perfect control over your torch angle, arc length, traveling speed, filler rate, etc. Not just to meet some engineer's specs, but simply to avoid turning the work piece into scrap. And on top of that you also do have to meet some engineers specs. Its genuinely horrendous to learn and lots of people just give up. Common practice is to simply see if you're better at another welding process, which basically means you stop learning TIG welding and switch to MIG or stick and do that for several weeks until you run into the same problems at which point you'll find yourself doing things like staring at blank spaces trying to figure out where in your life you made the mistake that set you on the path that led you this place.
It's really not. More infuriating than anything. Imagine you're painting a masterpiece, and about the time you're 90% done, your hand slips with the brush and paints a big slash across it. Yes it's fixable, but it's going to take a bunch of assache and the final product won't be as nice as it could have been. That's what it's like burning through on an open root.
>How does one make sure that a critical weld has what it takes?
Various examination procedures. When learning, you cut a welded plate into strips and bend it, which reveals structural defects. In an actual critical work piece, there will be some testing procedure specified, like magnaflux testing or X-ray examination, to make sure that the weld is good. Additionally, pressure vessels are pressurized to above their rated pressure to check for leaks or other failures.
>Im concerned about the weld being brittle, cant you make it pliable by heating it and letting it cool slowly?
With certain alloys, yes, but that also causes grain growth, which reduces toughness all else equal. It's generally preferable to use a ductile alloy in the first place. For stick welding mild steel, that means low-hydrogen rods like 7018 (which has been kept dry). Annealing doesn't remove entrapped hydrogen, or remove carbides from stainless that was welded with the wrong filler/gas.
>Can welded material be forged?
Depends on the alloy, but yes. It's usually preferable to fit and weld things so that the weldment is in the shape you want after it cools.
Its more fun to build smth that is barely strong enough and cheap.
There is no fun building house out of finger thick steel, its more fun to build a house out of aluminum can foil
I know its not welding but when gluing two surfaces together the resistance to shear is given as a force divided by the total area, not attaching at the center does weaken it.
Although the assembly as a whole will still be stronger than the individual plates of steel being welded
You have no idea how strong a weld is. It's fusing two pieces together. Apart from stuff like heat tempering or a bad weld, it's as strong as if a single piece was forged into that shape. You can't break metal just by hitting it with a hammer, so a good weld won't break on its own.
It can be more efficient than a butt joint in terms of filler use (for a given strength), but it's less efficient in terms of base metal use. It does shift maximum bending stress from the cast weld material to the (presumably wrought) base metal, which could be desirable, though it doesn't matter much for mild steel.
>Just burn it in real hot. it'll hold until it won't.
What is this supposed to mean? I feel like if you were talking to me IRL you would be waving your hands a lot and might punch a table to emphasize your riddle
I am a welder. I will explain.
the picture is not accurate. welds dont sit on top of the metal, they penetrate into it by melting the base material. you are basically fusing the two plates together and adding some fill material to fill the gap in.
it's stupid strong. cant say if the lap joint is stronger than a butt weld but I think it is since fillet welds (90 degrees) tend to be very good.
https://app.aws.org/forum/topic_show.pl?tid=25615 this explains it pretty well. basically it boils down to that a fillet weld always fails in shear regardless of loading direction. 900 lbs per 1/16th of weld throat per inch of weld is an easy number to remember for ballparking strength
if everything is clean and you burn shit in with dual shield, t8 innershield, or 7018, you don't need to work about the weld failing. usually it'll tear the base metal in the heat effected zone along the weld first
>https://app.aws.org/forum/topic_show.pl?tid=25615
What exactly is weld penetration? Either the metal is fused and forms a continuous mass or it isnt.
On OPs picture the weld metal forms a continuous mass with both plates, of similar cross section along the seam
Basically penetration is how far deep into the base metal the puddle went. The deeper the peneration the more area you've welded. For example if your doing a filet weld on two pieces that are 1/8th inch thick each qnd you just put down two welds that has 1/32 of peneration you'll have a section 1/16 wide where the two plates meet that's not welded. There's rules about how deep penetration has to go to meet certain specs or when it's gone too deep even. Sometimes that 1/16 unwelded area is totally pointless to fix, sometimes it's extremely important.
With OPs example a lot of people make a fuzz because most of area where the two plates overlap aren't welded. This could be fixed with something like forge weld but then your no longer talking about arc welding techniques but rather blacksmithing. Hell there could be cases where explosion welding is the best alternative.
What does it matter if the weld only penetrates 0.1 mm if you still get fusion of the material?
This is easier to see on a butt weld, you get two walls, these melt and fuse plus the filling metal. Does it matter if the fused region is deep as long as it covers the entire area?
>What does it matter if the weld only penetrates 0.1 mm if you still get fusion of the material?
More deeper penetration means more metal is fused which means a stronger weld. For example the thing you're welding might be expected to go through heat cycles during use. If you have trapped non-welded gaps they might have gases or liquids inside that expand and contract during the heat cycle, putting strain on the weld from within that eventually causes the weld to fail due to mechanical stresses while metal is weaker when it is hotter and wants to contract and expand on its own while heating up and cooling down. Same if its going through pressure cycles. In lots of applications the way you fix the issue of penetration is by removing large amounts of base metal and fill it up, then you do various tests to make sure its completely solid and if its not you grind those parts up and fill it back with weld again. I'm sure there's cases where you can do lap joints for pressure vessels but the butt joints are stronger simply because they don't have any gaps in them at all.
>I'm sure there's cases where you can do lap joints for pressure vessels
Lap joints are used in pressure vessels for repads, additional plates of material added to a vessel to provide reinforcement where needed, like around a large opening or where a structural support meets the pressure enclosure. They're also used to attach slip-on flanges to pipes. These usually require a lot more weld to meet spec than a butt-welded flange (though they don't require purge or back gouging), but they require a lot less machining to make.
Many welds spec full penetration. That requires the fusion zone completely encompasses the joint. Usually it's done by welding from both sides. You weld one side, then grind or gouge the backside down until you expose the back of the first weld, then fill the joint with weld. It makes for a truly seamless joint that doesn't have any defects to allow a crack begine easily or to propagate. Good weld joints are all about counteracting stress trying to tear the joint apart.
With small lap welds you can get immaculate part fitment on your tailgate with a handful of clamps instead of needing a fitting table, grinder, machine shop, etc. If you want to make strong parts in your driveway lap is the way.
this image is quite wrong, as the weld penetrates the surrounding metal, it has probably more connecting surface than the cross section of the metal to be connected
i make such welds to stainless steel tubes all the time at my job
if the tensile strength of the surface area of those two lines is the same of the section of one of the plates (or the smaller one) is ok to go
>tensile strength
So it should have the equivalent strength of the base plate with a loop of metal of the same thickness?
No, in your example, if one weld breaks, the thing falls apart. In the OP, you need two breaks before the thing pulls apart.
Wrong, if a loop breaks its still attached, unless you cut any of the plates the loop is attached to
Anon was talking about the WELD breaking. One of the welds attaching the loop to the plates.
If that weld breaks, the assembly comes part.
The anon here
talked about the weld breaking, not the loop. Everyone on the same page now?
If the metal breaks, then may God have mercy on your soul.
why not just use a bolt?
you can, even rivets, though you need the equivalent amount of them and making the holes and installing them require more work and time..
Sometimes you also can't, depending on the purpose or placement
Lol imagine a bolt in the middle of a car door.
A tank for example requires proper welds for structural integrity.
I see you don't know shit about welding. Most weld alloys are stronger than the base metal to begin with. Now, try to visualise the welded work as if it had been made from a single piece of metal bent in that shape. The fillet is about as thick as the metal itself.
>Most weld alloys are stronger than the base metal to begin with.
So what? Yes its a stronger metal but its still covering only a small percentage of the area.
Did you read the rest? It's the same (more or less) as if you bent that piece.
>as if you bent that piece.
You cant bend a single steel plate into that shape
>How efficient are lap welds for joining two plates
Compared to what? Butt joints?
>can't
You can put a brake into a plate.
>Compared to what? Butt joints?
In the sense that the bulk of the metal isnt contributing to any strength. It may in some cases only
How so? It's welded twice (lower rate of failure) and it's double the thickness for some span, so it has twice the bending resistance at the lap. The lap is not fused over the entire area but it does not matter the slightest bit.
When you're welding a corner angle, you leave the fillet there because it's not in the way and it would be extra work to take it off, but if you had complete penetration of the joint, you could grind away pretty much all of the fillet and it would hold just fine, as if you had put a bend in a single piece.
>How efficient are lap welds for joining two plates
Watch Camarata try to break this weld: https://youtu.be/uSY5vBl1V44?si=NzwDpDt6kiKKIHr_&t=3119
How dishonest. That isnt the only type of stress you can apply and worse, to concentrate it on a single point.
And that's a shitty weld.
why not just butt weld...
because you can learn lap joint in less than 10 hours of practice while x-ray proof butt joints are 100 hours or more.
Why are butt weld much harder? Is it because you have to bevel them and fill that groove with more passes?
How does one make sure that a critical weld has what it takes? Im concerned about the weld being brittle, cant you make it pliable by heating it and letting it cool slowly?
Can welded material be forged? I say it because these butt welds always curve, is it possible to heat them red hot and bend them into shape?
>Why are butt weld much harder? Is it because you have to bevel them and fill that groove with more passes?
Yes but there's way more to it than that. On the root pass you're constantly walking a balance with the heat of the puddle because too little and you don't get proper fusion but too much and you overheat the puddle and burn a giant hole in the joint with white hot metal and slag falling off, hitting the floor and splashing all around you. On the first fill pass you can even get too hot and end up doing a second root pass which fails the joint, while still dealing with the issue that you might burn a hole into the joint like before. In theory its same stuff you do on other joints but with butt joints you simply have less room for error. You need perfect control over your torch angle, arc length, traveling speed, filler rate, etc. Not just to meet some engineer's specs, but simply to avoid turning the work piece into scrap. And on top of that you also do have to meet some engineers specs. Its genuinely horrendous to learn and lots of people just give up. Common practice is to simply see if you're better at another welding process, which basically means you stop learning TIG welding and switch to MIG or stick and do that for several weeks until you run into the same problems at which point you'll find yourself doing things like staring at blank spaces trying to figure out where in your life you made the mistake that set you on the path that led you this place.
that seems scary
It's really not. More infuriating than anything. Imagine you're painting a masterpiece, and about the time you're 90% done, your hand slips with the brush and paints a big slash across it. Yes it's fixable, but it's going to take a bunch of assache and the final product won't be as nice as it could have been. That's what it's like burning through on an open root.
>How does one make sure that a critical weld has what it takes?
Various examination procedures. When learning, you cut a welded plate into strips and bend it, which reveals structural defects. In an actual critical work piece, there will be some testing procedure specified, like magnaflux testing or X-ray examination, to make sure that the weld is good. Additionally, pressure vessels are pressurized to above their rated pressure to check for leaks or other failures.
>Im concerned about the weld being brittle, cant you make it pliable by heating it and letting it cool slowly?
With certain alloys, yes, but that also causes grain growth, which reduces toughness all else equal. It's generally preferable to use a ductile alloy in the first place. For stick welding mild steel, that means low-hydrogen rods like 7018 (which has been kept dry). Annealing doesn't remove entrapped hydrogen, or remove carbides from stainless that was welded with the wrong filler/gas.
>Can welded material be forged?
Depends on the alloy, but yes. It's usually preferable to fit and weld things so that the weldment is in the shape you want after it cools.
Its more fun to build smth that is barely strong enough and cheap.
There is no fun building house out of finger thick steel, its more fun to build a house out of aluminum can foil
I know its not welding but when gluing two surfaces together the resistance to shear is given as a force divided by the total area, not attaching at the center does weaken it.
Although the assembly as a whole will still be stronger than the individual plates of steel being welded
You have no idea how strong a weld is. It's fusing two pieces together. Apart from stuff like heat tempering or a bad weld, it's as strong as if a single piece was forged into that shape. You can't break metal just by hitting it with a hammer, so a good weld won't break on its own.
You should see a butt weld. Most of the metal isn't attached to anything it is just held by one line of filler material!
It can be more efficient than a butt joint in terms of filler use (for a given strength), but it's less efficient in terms of base metal use. It does shift maximum bending stress from the cast weld material to the (presumably wrought) base metal, which could be desirable, though it doesn't matter much for mild steel.
Welding noob here. How else would you weld this together other than a butt joint?
Weld what together?
Your butt so you can't shit no more.
Nuh uh
Just burn it in real hot. it'll hold until it won't.
>Just burn it in real hot. it'll hold until it won't.
What is this supposed to mean? I feel like if you were talking to me IRL you would be waving your hands a lot and might punch a table to emphasize your riddle
Not that anon, but it means exactly what I says.
X-Y question. What are you welding?
I am a welder. I will explain.
the picture is not accurate. welds dont sit on top of the metal, they penetrate into it by melting the base material. you are basically fusing the two plates together and adding some fill material to fill the gap in.
it's stupid strong. cant say if the lap joint is stronger than a butt weld but I think it is since fillet welds (90 degrees) tend to be very good.
https://app.aws.org/forum/topic_show.pl?tid=25615 this explains it pretty well. basically it boils down to that a fillet weld always fails in shear regardless of loading direction. 900 lbs per 1/16th of weld throat per inch of weld is an easy number to remember for ballparking strength
if everything is clean and you burn shit in with dual shield, t8 innershield, or 7018, you don't need to work about the weld failing. usually it'll tear the base metal in the heat effected zone along the weld first
With that kind of penetration? Might as well use super glue.
>https://app.aws.org/forum/topic_show.pl?tid=25615
What exactly is weld penetration? Either the metal is fused and forms a continuous mass or it isnt.
On OPs picture the weld metal forms a continuous mass with both plates, of similar cross section along the seam
Basically penetration is how far deep into the base metal the puddle went. The deeper the peneration the more area you've welded. For example if your doing a filet weld on two pieces that are 1/8th inch thick each qnd you just put down two welds that has 1/32 of peneration you'll have a section 1/16 wide where the two plates meet that's not welded. There's rules about how deep penetration has to go to meet certain specs or when it's gone too deep even. Sometimes that 1/16 unwelded area is totally pointless to fix, sometimes it's extremely important.
With OPs example a lot of people make a fuzz because most of area where the two plates overlap aren't welded. This could be fixed with something like forge weld but then your no longer talking about arc welding techniques but rather blacksmithing. Hell there could be cases where explosion welding is the best alternative.
A picture to illustrate the example.
What does it matter if the weld only penetrates 0.1 mm if you still get fusion of the material?
This is easier to see on a butt weld, you get two walls, these melt and fuse plus the filling metal. Does it matter if the fused region is deep as long as it covers the entire area?
>What does it matter if the weld only penetrates 0.1 mm if you still get fusion of the material?
More deeper penetration means more metal is fused which means a stronger weld. For example the thing you're welding might be expected to go through heat cycles during use. If you have trapped non-welded gaps they might have gases or liquids inside that expand and contract during the heat cycle, putting strain on the weld from within that eventually causes the weld to fail due to mechanical stresses while metal is weaker when it is hotter and wants to contract and expand on its own while heating up and cooling down. Same if its going through pressure cycles. In lots of applications the way you fix the issue of penetration is by removing large amounts of base metal and fill it up, then you do various tests to make sure its completely solid and if its not you grind those parts up and fill it back with weld again. I'm sure there's cases where you can do lap joints for pressure vessels but the butt joints are stronger simply because they don't have any gaps in them at all.
>I'm sure there's cases where you can do lap joints for pressure vessels
Lap joints are used in pressure vessels for repads, additional plates of material added to a vessel to provide reinforcement where needed, like around a large opening or where a structural support meets the pressure enclosure. They're also used to attach slip-on flanges to pipes. These usually require a lot more weld to meet spec than a butt-welded flange (though they don't require purge or back gouging), but they require a lot less machining to make.
Many welds spec full penetration. That requires the fusion zone completely encompasses the joint. Usually it's done by welding from both sides. You weld one side, then grind or gouge the backside down until you expose the back of the first weld, then fill the joint with weld. It makes for a truly seamless joint that doesn't have any defects to allow a crack begine easily or to propagate. Good weld joints are all about counteracting stress trying to tear the joint apart.
With small lap welds you can get immaculate part fitment on your tailgate with a handful of clamps instead of needing a fitting table, grinder, machine shop, etc. If you want to make strong parts in your driveway lap is the way.
this image is quite wrong, as the weld penetrates the surrounding metal, it has probably more connecting surface than the cross section of the metal to be connected
i make such welds to stainless steel tubes all the time at my job