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Socket weld leaks at overlap/crater

Socket weld leaks at overlap/crater

Socket weld leaks at overlap/crater

(OP)
Hi All, I'm trying to decrease frequency of weld leaks in an automated GMAW-P socket weld process.

It is a weld between a "cap" and a tube which are pressed together, then welded in an automated rotating fixture.

It is SAE 1010 steel, and the cap has wall thickness .080" and the tube is .049"

The weld only ever leaks at the overlap pass, at the crater and its always on the tube side of the weld.

Any suggestions for crater options or burnback etc. ?

see picture for clarity of the part.

Thanks

RE: Socket weld leaks at overlap/crater

Can you continue the weld around.  So you are welding 365 degrees instead of 360, resulting in a little weld overlap at the end of the weld?

Regards
Stonecold

RE: Socket weld leaks at overlap/crater

(OP)
Yes, the weld goes past 360 degrees, about 3/8" overlap.  

RE: Socket weld leaks at overlap/crater

What you are more than likley experiencing is gas evolution at the tie-in loacation. If you have appropriate controls, slow down the travel speed and slightly increase the wire feed speed to permit the gas to escape at the tie in location. IF you have down sloping current control, use it after you have passed the tie-in location.

A competent, manual welder would readily compensate. Essentially, you need to mimic what he would do wiyh your automatic process.  

RE: Socket weld leaks at overlap/crater

current ramp up at the beginning of the weld and ramp down after the completion will help.
The ramp at the start acts as a pre-heat on this metal so that when you come around and weld over it you get good fusion with less gas evolution.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

RE: Socket weld leaks at overlap/crater

Is it a closed vessel?

RE: Socket weld leaks at overlap/crater

Program it to do what an experienced welder does:  breal the arc at 365°, hesitate 1 to 1.5 seconda and then 'blip' the gun for crater fill.

Also possible that the porosity is from gas evolution from lack-of-cleanliness.  GMAW, being fluxless, has almost zero tolerance for oil, etc.

RE: Socket weld leaks at overlap/crater

TheRyno,

What is causing the weld to leak?  

Are you blowing thru the .049" tube wall or not fusing?

I agree with stanweld, your parameters need to be modified, however the condition causing the leak will depend on how you modify. Another parameter to consider is the diameter of the wire.

If you are blowing thru you could decrease the overlap to avoid excessive heat input.

RE: Socket weld leaks at overlap/crater

AS Tmoose asked, is the tube a closed volume or is it free to vent?

RE: Socket weld leaks at overlap/crater

TheRyno,

Were you able to remedy this issue?  If so how did you accomplish?

 

RE: Socket weld leaks at overlap/crater

(OP)
The volume is open to vent. The leaks still occur, they are only about 1% of total parts, but they always still leak at the same location. I haven't had much time to do further trials but might be able to soon. Again I appreciate the help from everyone.  

RE: Socket weld leaks at overlap/crater

If your are pressing the parts together with significant force, welding, immediately releasing the force you may be creating cracks at the weld termination.

Suggest dye penetrate testing these areas.

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