Need some welding questions answered

[Garage5.9]

As far as welding goes i wouldn't say im a 100% rookie but im not gonna say im good but maybe good enough as long as it isn't structrual or if some ones life depends on it i can burn it together and not have it fall apart. Now my questions are

1. If im making a fillet weld and i start welding and go for about 3-4 inches , stop. Reposition or for what ever reason then start again is the weld weaker than a single pass not stopping at all ?

2. My current machine is a cheap lincoln 150 HD flux core 110v and all is well with this thing for what i do but my questions is why do some of my welds have holes in the slag/weld when some times i make a pass and it ways nicer with out these little holes ? Im guessing inconsistent speed ? or is it something else.

any info is appreciated

 

[Dara]

to answer Q 1 your aim if you have to stop start weld is not to leave a hole inside the weld where you stopped an restarted...best thing to do is go back about 20mm on the weld you jus done from where you stopped an start there that way it fills in any potential hole that would have been left where you stopped..the weld will be fine then as long as its penetratin into both metals on the fillet

 

[Heavy Metal Doctor]

#1 - Doesn't matter as long they are good welds - and be sure the re-start burns in good to the previous one.

#2 - Dirty material being welded or shield gas blowing away.


There may be some textbook answers that say I'm wrong though, since I'm not a full-on welder by trade. My answers only come from a high school welding class in 1986 and fabrication work at my job since '95....none of my work has ever failed to my knowledge....

 

[Garage5.9]

to answer Q 1 your aim if you have to stop start weld is not to leave a hole inside the weld where you stopped an restarted...best thing to do is go back about 20mm on the weld you jus done from where you stopped an start there that way it fills in any potential hole that would have been left where you stopped..the weld will be fine then as long as its penetratin into both metals on the fillet

cool , i kinda figured if i went back a little over the previous weld i should but good but just wanted to confirm with some more seasoned people.

#1 - Doesn't matter as long they are good welds - and be sure the re-start burns in good to the previous one.

#2 - Dirty material being welded or shield gas blowing away.


There may be some textbook answers that say I'm wrong though, since I'm not a full-on welder by trade. My answers only come from a high school welding class in 1986 and fabrication work at my job since '95....none of my work has ever failed to my knowledge....

The material is pretty clean ive grounded all the mill scale or what ever its called off the flat stock and both sides. no chance of shield gas blowing away because im using a fluxcore machine at the moment. I have semi nice "dimes" flowing in the weld but every so often theres these holes that make the weld look like ****.

 

[Murphy4570]

cool , i kinda figured if i went back a little over the previous weld i should but good but just wanted to confirm with some more seasoned people.


The material is pretty clean ive grounded all the mill scale or what ever its called off the flat stock and both sides. no chance of shield gas blowing away because im using a fluxcore machine at the moment. I have semi nice "dimes" flowing in the weld but every so often theres these holes that make the weld look like ****.

You're using flux core, it's not gonna look pretty unless you have years of experience with it.

Little holes as you go along are probably from you going too fast. Slow down and take your time making the bead, watch the puddle. You can add another bead on top to seal the holes if you like, and make it look better.

 

[Heavy Metal Doctor]

You're using flux core, it's not gonna look pretty unless you have years of experience with it.

Little holes as you go along are probably from you going too fast. Slow down and take your time making the bead, watch the puddle. You can add another bead on top to seal the holes if you like, and make it look better.

I guess I've been lucky with with my cheapo little flux core set-up at home.....

 

[aka Larry]

One disadvantage to using the flux core is you can't just stop the bead and then start back over the edge of the previous one. If you are doing this, the slag left behind from the flux will cause inclusions in the new bead. So if you want to stop you need to remove the slag before restarting. Of course if you use the shielding gas, this problem is moot.

My main gripe with using the flux core is all the smoke. It makes it harder to see the puddle and keep the bead consistant not to mention the harmful affects of breathing that stuff into your lungs.

 

[MoonRise]

As far as welding goes i wouldn't say im a 100% rookie but im not gonna say im good but maybe good enough as long as it isn't structrual or if some ones life depends on it i can burn it together and not have it fall apart. Now my questions are

1. If im making a fillet weld and i start welding and go for about 3-4 inches , stop. Reposition or for what ever reason then start again is the weld weaker than a single pass not stopping at all ?

2. My current machine is a cheap lincoln 150 HD flux core 110v and all is well with this thing for what i do but my questions is why do some of my welds have holes in the slag/weld when some times i make a pass and it ways nicer with out these little holes ? Im guessing inconsistent speed ? or is it something else.

any info is appreciated

#1. Yes and no. If you have a stop and a start and don't properly tie the two together, then you can have a 'weaker' weld.

If you don't 'properly' actually weld the things together and just 'caulk' some molten wire filler on top of the parent metal without fusing the piece(s) of parent material and the molten weld filler all into one, then you will have a weaker weld.

#2. Some small holes in the slag is no problem. Some small 'pinholes' in the weld bead itself is not so good. Porosity can be commonly caused by crud (clean the steel well before welding), the voltage being set too high for the amperage/WFS being used, the WFS/amperage being set too low for the voltage being used, too fast of a travel speed being used, or too much of a drag angle being used.

Read up over on the Lincoln or Miller or ESAB websites. Tons of information.

http://www.lincolnusmarketing.com/products.asp?cat=CAT105

Especially

http://www.lincolnelectric.com/assets/en_US/Products/literature/C32400.pdf

See Page #25 there especially.

Also see

http://www.lincolnelectric.com/assets/en_US/Products/literature/C4200.pdf

for some good info about GMAW and general wire-feed welding.

Miller's website http://www.milerwelds.com

ESAB's website (North America)

http://www.esabna.com

especially the "Education" section

http://esabna.com/us/en/education/index.cfm

http://esabna.com/us/en/education/esab-university.cfm

http://www.esabna.com/EUWeb/AWTC/Lesson1_1.htm

 

[bika bill]

1. A grinder is a welder's best friend. Always grind stops smooth before re-starting. Metallurgically you don't hurt the steel at all (low carbon like A36, that is). Actually, multi-pass welds provide beneficial tempering.
2. All the above plus beware of stick out -- distance from tip to work -- usually about 1/2 to one inch works for me. (But that's not to say I make pretty welds, still working on that.)

 

[Garage5.9]

One disadvantage to using the flux core is you can't just stop the bead and then start back over the edge of the previous one. If you are doing this, the slag left behind from the flux will cause inclusions in the new bead. So if you want to stop you need to remove the slag before restarting. Of course if you use the shielding gas, this problem is moot.

My main gripe with using the flux core is all the smoke. It makes it harder to see the puddle and keep the bead consistant not to mention the harmful affects of breathing that stuff into your lungs.

Thanks on the tip about not restarting on the slag. I will be in the near future will be buying something with gas not sure on what machine yet , any reccomendations ? I plan to spend no more than a G

#1. Yes and no. If you have a stop and a start and don't properly tie the two together, then you can have a 'weaker' weld.

If you don't 'properly' actually weld the things together and just 'caulk' some molten wire filler on top of the parent metal without fusing the piece(s) of parent material and the molten weld filler all into one, then you will have a weaker weld.

#2. Some small holes in the slag is no problem. Some small 'pinholes' in the weld bead itself is not so good. Porosity can be commonly caused by crud (clean the steel well before welding), the voltage being set too high for the amperage/WFS being used, the WFS/amperage being set too low for the voltage being used, too fast of a travel speed being used, or too much of a drag angle being used.

Read up over on the Lincoln or Miller or ESAB websites. Tons of information.

http://www.lincolnusmarketing.com/products.asp?cat=CAT105

Especially

http://www.lincolnelectric.com/assets/en_US/Products/literature/C32400.pdf

See Page #25 there especially.

Also see

http://www.lincolnelectric.com/assets/en_US/Products/literature/C4200.pdf

for some good info about GMAW and general wire-feed welding.

Miller's website http://www.milerwelds.com

ESAB's website (North America)

http://www.esabna.com

especially the "Education" section

http://esabna.com/us/en/education/index.cfm

http://esabna.com/us/en/education/esab-university.cfm

http://www.esabna.com/EUWeb/AWTC/Lesson1_1.htm

Thanks for the tips on the wire speed/voltage. The thing with this machine is there isn't to much adjustability with the heat , there is only low/hi basically.

1. A grinder is a welder's best friend. Always grind stops smooth before re-starting. Metallurgically you don't hurt the steel at all (low carbon like A36, that is). Actually, multi-pass welds provide beneficial tempering.
2. All the above plus beware of stick out -- distance from tip to work -- usually about 1/2 to one inch works for me. (But that's not to say I make pretty welds, still working on that.)

Thanks for the tips

 

[kald]

cool , i kinda figured if i went back a little over the previous weld i should but good but just wanted to confirm with some more seasoned people.


The material is pretty clean ive grounded all the mill scale or what ever its called off the flat stock and both sides. no chance of shield gas blowing away because im using a fluxcore machine at the moment. I have semi nice "dimes" flowing in the weld but every so often theres these holes that make the weld look like ****.

I wouldn't worry to much about "stacking dimes". Just concentrate on good, mechanically solid welds. http://www.weldingtipsandtricks.com/ is a good site with lots of videos. Not sure if he has any flux core videos but you still pick up a ton of good info by watching the videos for the other processes.

 

[Garage5.9]

I wouldn't worry to much about "stacking dimes". Just concentrate on good, mechanically solid welds. http://www.weldingtipsandtricks.com/ is a good site with lots of videos. Not sure if he has any flux core videos but you still pick up a ton of good info by watching the videos for the other processes.

Ill be sure to check this out. I try to stack dimes but with the flux core it looks more like a stacked pile of **** haha but still i like to try to get that stacked look some what. This welding thing is getting kind of addictive i really enjoy burning **** together

 

[dr_clyde]

Lots of good info already, but I'll add my professional welder's 2 cents.

Porosity is ALWAYS a function of shielding. This could be the result of pockets of crud ougassing active gases into the inert sheild, gas being blown away, bad gas, or a hollow pocket of no flux in the wire. I realize you are using flux core so there is no gas, but with some welders, you can do what is called dual shield welding. This is using gas with the flux wire. Kind of uncommon, but I've done it in the shop pipe welding. Going back over your previous weld trying to create a "stack of dimes" with flux core is a no no. The weld can trap pockets of slag and create defects and other problems. I wouldn't be surprised if that is what was causing your porosity problem.

Flux core welding was designed to be used in an outdoor setting in the spray transfer mode of deposit. It creates a weld that resembles a properly done 7018 stick weld. However, welder manufacturers sell smaller welding outfits with flux core wire to guys without the budget to get a bigger machine capable of spray transfer. This isn't to say that flux core won't work with short arc, it just is very messy and much more difficult to get consistent, good welds. If you can get shielding gas, do it.

Restarts are a common, necessary, and metallurgically acceptable welding practice. In critical welding, ie structural steel, pressure vessels, or tanks, it is important they are done properly.

First, grab a chipping hammer and a wire brush. Scrape the hammer over the flux to remove it. Chipping hammer is kind of a misnomer, because you seldom hammer with it. Pock marks all over the weld are signs of a rookie weld. Slag shouldn't fight you to come off. Wire brush the area where you are going to restart. There should be NO slag or spatter. grab a 4.5" grinder with a rock if you need it. This area should be clean and smooth. Light up about a quarter inch ahead of where your last bead ended. Quickly, before you puddle, focus on the end of the previous bead until a good hot puddle forms. Then proceed with the weld. This ensures no arc marks or bad deposits on the visible weld. It is necessary when certifying for pipe welding; the inspectors don't like to see arc marks or spatter on the cap or the pipe.

Good luck. Practice makes perfect.

 

[kald]

Lots of good info already, but I'll add my professional welder's 2 cents.

Porosity is ALWAYS a function of shielding. This could be the result of pockets of crud ougassing active gases into the inert sheild, gas being blown away, bad gas, or a hollow pocket of no flux in the wire. I realize you are using flux core so there is no gas, but with some welders, you can do what is called dual shield welding. This is using gas with the flux wire. Kind of uncommon, but I've done it in the shop pipe welding. Going back over your previous weld trying to create a "stack of dimes" with flux core is a no no. The weld can trap pockets of slag and create defects and other problems. I wouldn't be surprised if that is what was causing your porosity problem.

Flux core welding was designed to be used in an outdoor setting in the spray transfer mode of deposit. It creates a weld that resembles a properly done 7018 stick weld. However, welder manufacturers sell smaller welding outfits with flux core wire to guys without the budget to get a bigger machine capable of spray transfer. This isn't to say that flux core won't work with short arc, it just is very messy and much more difficult to get consistent, good welds. If you can get shielding gas, do it.

Restarts are a common, necessary, and metallurgically acceptable welding practice. In critical welding, ie structural steel, pressure vessels, or tanks, it is important they are done properly.

First, grab a chipping hammer and a wire brush. Scrape the hammer over the flux to remove it. Chipping hammer is kind of a misnomer, because you seldom hammer with it. Pock marks all over the weld are signs of a rookie weld. Slag shouldn't fight you to come off. Wire brush the area where you are going to restart. There should be NO slag or spatter. grab a 4.5" grinder with a rock if you need it. This area should be clean and smooth. Light up about a quarter inch ahead of where your last bead ended. Quickly, before you puddle, focus on the end of the previous bead until a good hot puddle forms. Then proceed with the weld. This ensures no arc marks or bad deposits on the visible weld. It is necessary when certifying for pipe welding; the inspectors don't like to see arc marks or spatter on the cap or the pipe.

Good luck. Practice makes perfect.

Good post!

 

[Ozwelder]

1. If im making a fillet weld and i start welding and go for about 3-4 inches , stop. Reposition or for what ever reason then start again is the weld weaker than a single pass not stopping at all ?

2. My current machine is a cheap lincoln 150 HD flux core 110v and all is well with this thing for what i do but my questions is why do some of my welds have holes in the slag/weld when some times i make a pass and it ways nicer with out these little holes ? Im guessing inconsistent speed ? or is it something else.

1. Given that the welding is performed correctly, no problem- a stop start is equal in strength to a full bead. A potential failure point can be the crater left, when the arc is broken. On stressed work it can give rise to cracking from the thin section of the crater. Fill the crater at the end of the bead or on a restart, start the arc a bit down stream from the crater and snap back and fill the crater move off and continue with the bead. The time span is almost like snapping your fingers - its that quick.

The crater is only critical to failure when there is a high loading on the weldment.


2. Not owning a small machine like yours ,I can only surmise,but experience tells me the porousities are caused from ; unclean base material or contaminants ,ie rust, oil and paint, or lack of shielding.

Arc voltage can be critical on larger machines and possibly is so on yours.On smaller machines I have used I have found somewhere around 21 volts is the sweet spot for FCAW wire.

Also dragging as opposed to pushing -as in GMAW often makes a big difference.

Does this help?

 

[Garage5.9]

1. Given that the welding is performed correctly, no problem- a stop start is equal in strength to a full bead. A potential failure point can be the crater left, when the arc is broken. On stressed work it can give rise to cracking from the thin section of the crater. Fill the crater at the end of the bead or on a restart, start the arc a bit down stream from the crater and snap back and fill the crater move off and continue with the bead. The time span is almost like snapping your fingers - its that quick.

The crater is only critical to failure when there is a high loading on the weldment.


2. Not owning a small machine like yours ,I can only surmise,but experience tells me the porousities are caused from ; unclean base material or contaminants ,ie rust, oil and paint, or lack of shielding.

Arc voltage can be critical on larger machines and possibly is so on yours.On smaller machines I have used I have found somewhere around 21 volts is the sweet spot for FCAW wire.

Also dragging as opposed to pushing -as in GMAW often makes a big difference.

Does this help?

Alot of info to absorb but yes this does help as it give me a better understanding. Ill post some pics of my beautiful welds when i get a chance and your pros can tell me what im doing wrong/right

 

[Mechsoldier]

I have a Millermatic 180 with a spool gun which allows you to weld stainless and aluminum as well with the correct gasses, although the weld is no where near as pretty as tig so I'm trying to pick one of those up.

Edit: Technically you can weld stainless with a standard mig torch but the weld will rust. Spool gun allows stainless wire to be used (without trying to feed it through the torch like normal wire which is technically possible but a pain in the ****)

Anyways, flux core *****, you can't use it on anything thin because it's too hot, it looks crappy, and slag gets everywhere.