stud weld - continuous breakage 1

[dogbural]

Hi,
I have a plate with studs welded. Some of the studs ended up breakage while applying torque.
Looking at the broken face, would it be any possible cause for this failure?
Supplier also checked the parts by applying the torque. In their end, the parts are all conforming. But sometimes, we faced such failure.

 

[FacEngrPE]

ANSI/AWS C5.4-93 Recommended Practices for Stud Welding
Sample at the AWS store

See Also AWS D1.1 section on developing WPS for stud welding

and
thread178-415358

 

[TugboatEng]

Removing the zinc plating prior to welding both defeats the purpose of having zinc plating and is labor intensive. Perhaps there is a stud that can be welded through the zinc plating. I suggest trying silicon bronze studs. You may need to use a flux.

https://www.tescosteel.com/silicon-bronze-weld-studs-manufacturer-supplier.html

I have had good luck torch brazing silicon bronze on zinc plated steel.

 

[mfgenggear]

Welding zinc is deadly poisonous

 

[TugboatEng]

A problem that is easily mitigated with ventilation.

 

[DVWE]

I don’t know that I would say deadly poisonous, but it certainly isn’t good to breath. Most people who experience excessive zinc inhalation from welding describe it as a flu-like symptom, which is usually abated by a glass of milk or two.

It may become deadly after long term, high exposure rates.

The devil is in the details; she also wears prada.

 

[mfgenggear]

I know of welders that passed from breathing in fumes.

 

[mfgenggear]

https://www.metalfinishingsltd.co.uk/articles/welding-zinc-coatings/

 

[dogbural]

thanks guys, I will have discussion with our eng team.

 

[dogbural]

supplier just confirmed that the parts are plated after weld.

Stud is made of copper.

Supplier advised that the possible reason for the broken stud is due to the stud being slanted during welding process.
Every round of torque testing/ tightening process, the force that applied at the slanted stud eventually damaged the welding condition.

There are two challenges for their current method.
One is the binding between the stud and plate; As it’s manually weld, there might be inconsistency of the welding condition.
Second is the slanted stud during welding process. Although 100% visual inspection on the studs, if the studs insignificantly slanted, it will be challenge to detect.

To be more detailed, currently supplier verify the stud/weld condition by tightening the nut at the stud with specific range of torque.
Do you think the bending method would be more beneficial, like advised earlier.

https://www.youtube.com/watch?v=cwE5YPy4ztE&t=5s

 

[mfgenggear]

Op
Do they have a weld schedule, (wps)
Was there documentation of the weld inspected and verified with an inspector.
The welds that Crack have lack of penetration
It's been a while were the settings of the machine recorded.
The work Holding sufficient to maintain squareness to the machine.

 

[3DDave]

The studs don't look like copper. If they are, then they are plated over the copper. What is the plating? Consider a copper plated steel stud to weld to steel.

The weld has incomplete fusion - it looks contaminated.

 

[TugboatEng]

It's common for steel studs to be copper plated, many welding rods and wires are copper plated as well. The coating prevents corrosion and burns off during the welding process. Copper itself cannot be welded directly to steal. There are copper alloys that can be welded directly to steel. These will usually have quite a bit of nickel in them.

 

[gtaw]

What type of stud welding equipment is being used? Are these actual studs or are they more like a projection weld in that there is a small nub that acts as a stand off? There are several variations and each has its own particularities. Consistent results require consistent welding parameters and consistent base metal preparation.

Best regards - Al