How do I tell if a weld is strong?

[Thebeast]

Hi I bought a old Clarke 210 amp stick welder (ac) I am new to stick welding.

Bought some 6013 electrodes (2.5mm) and I have been practicing on 3mm thick mild steel. Running straight lines and everything was fine. Decided to do T joints just one side only and bend tested them and the weld snaps right in half pretty easily.

For a weld to be strong shouldn’t the metal I’m welding too break before the weld?

 

[Barking Mat]

Try hitting it, destructive testing.

 

[Richiew]

Stick welds usually hold up. What are you ultimately trying to build?

 

[Screwdriver]

Hi I bought a old Clarke 210 amp stick welder (ac) I am new to stick welding.

Bought some 6013 electrodes (2.5mm) and I have been practicing on 3mm thick mild steel. Running straight lines and everything was fine. Decided to do T joints just one side only and bend tested them and the weld snaps right in half pretty easily.

For a weld to be strong shouldn’t the metal I’m welding too break before the weld?

Difficult to say because there's no real strength opening up a weld from the back side. Best bet is to stick up some pictures. For it to be weak, you might have poor penetration or contamination and that should be obvious from the pictures.

 

[voipio]

Look at how the weld metal was deposited, and try and get some idea of how well the filler metal has penetrated into the parts being welded. Good penetration is necessary for a strong weld. Once the arc is established, it's necessary to almost push the rod into the weld pool, in order to get the necessary penetration. 2.5mm rods are a bit on the thin side for practising with. I started with 1.6mm rods, many years ago, and they were a complete nightmare, at the beginning. 3.2mm rods are much easier to work with, using a suitable current.

 

[Thebeast]

So is it quite normal for a weld to break in half easily by bending it back over itself?

Look at how the weld metal was deposited, and try and get some idea of how well the filler metal has penetrated into the parts being welded. Good penetration is necessary for a strong weld. Once the arc is established, it's necessary to almost push the rod into the weld pool, in order to get the necessary penetration.

When I was welding the arc was really aggressive. I’m guessing my arc was too far out from the pool? Could this be a problem and causing poor penetration?

 

[Richiew]

Keep the rod buried if you can. Excessive arc length is a bad thing. As a beginner, you are likely to have too long an arc length rather than too short.

 

[voipio]

So is it quite normal for a weld to break in half easily by bending it back over itself?

Only if penetration is poor, and the metal hasn't been prepared ideally. A better result will be achieved, if welding from one side, if the parts being welded are chamfered, so that they form a V-groove when put against each other, prior to welding. That way the molten filler metal has access to the full thickness of the parts being welded. With this method, there's often no need to then weld from the other side.

When I was welding the arc was really aggressive. I’m guessing my arc was too far out from the pool? Could this be a problem and causing poor penetration?

Yes. As Richiew said in their posting above.

 

[Screwdriver]

Yes. You can tack say a bracket in place as a temporary support which is strong in tension or if you bend the material such that it is trying to lift up the weld. If you do as you are doing which is to bend the part towards the weld, opening it up from the rear, there is a HUGE amount of leverage and you are bending the weld rather than pulling on it. Should snap off like a carrot.

Better test is to weld both sides of the "T" and hit it with a hammer. Then I would expect a good solid weld to tear up the parent material or bend depending on the strength/shape of the test piece.

<edit> Oh yeah, you can really shove the end of the rod right in there. I like to be able to feel it disappearing as the rod collapses with the arc. Don't poke it out the other side though...

PS I am not a good welder. Better ought to mention that.

 

[Richiew]

Photos please.

 

[voipio]

The tutorial linked to at the top of the forum pages is very useful:

Arc Welding Tutorial

This practical arc welding tutorial, supported by videos, is intended to bring a complete beginner up to a basic standard of welding

www.mig-welding.co.uk

 

[Thebeast]

Yes. You can tack say a bracket in place as a temporary support which is strong in tension or if you bend the material such that it is trying to lift up the weld. If you do as you are doing which is to bend the part towards the weld, opening it up from the rear, there is a HUGE amount of leverage and you are bending the weld rather than pulling on it. Should snap off like a carrot.

Better test is to weld both sides of the "T" and hit it with a hammer. Then I would expect a good solid weld to tear up the parent material or bend depending on the strength/shape of the test piece.

<edit> Oh yeah, you can really shove the end of the rod right in there. I like to be able to feel it disappearing as the rod collapses with the arc. Don't poke it out the other side though...

PS I am not a good welder. Better ought to mention that.

This makes a lot more sense to me now. Thank you :-) yeah I was tack welding with stick and they seem extremely weak like if I move the material it just falls off or the tack weld itself just comes off like a blob of hot solder has fell and splashed on the material. I’m guessing when I tack weld I need to really push the rod in more?

 

[Richiew]

A tack weld is only there to hold the material in place to be fully welded. It's a place holder. Don't mistake it for proper welding.

 

[Thebeast]

A tack weld is only there to hold the material in place to be fully welded. It's a place holder. Don't mistake it for proper welding.

Yeah I know that mate I was just on about in general I noticed when I done a few tack welds they where not penetrating one little bit. I’m guessing because I wasn’t pushing the rod right in