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Stud Welding Troubleshooting Guide
This stud welding troubleshooting guidance document contains useful information from ISO 14555, along with some additional supplementary information that will allow users to troubleshoot some common welding problems. If you still require help or advice, our team are on hand to help, just give us a call on 01924 452123
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Acceptable materials
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Certain combinations of materials are recommended for better compatibility with stud welding processes. Studwelding is not restricted to these combinations, but weldability of other materials not mentioned in the tables below should be assured by appropriate WPS or WPQR requirements.
Welding Compatibility of Materials Using the Drawn Arc or
Drawn Arc Short Cycle Processes
Stud Material
Parent Materials
ISO/TR 15608 material groups 1 and 2.1
ISO/TR 15608 material groups 2.2 and 3-6
ISO/TR 15608 material groups 8 and 10
ISO/TR 15608 material groups 21 and 22
S235
4.8 (weldable)
16Mo3
Highly weldable for any application (a)
Weldable within limits (b)
Weldable within limits (b,c)
Not weldable
1.4742
1.4762
Weldable within limits (d)
Weldable within limits (d)
Weldable within limits (d)
Not weldable
1.4828
1.4841
Weldable within limits (b)
Weldable within limits (b)
Weldable within limits (b)
Not weldable
1.4301
1.4303
1.4401
1.4529
1.4541
1.4571
Weldable within limits (b) / Highly weldable for any application (a,e)
Weldable within limits (b)
Highly weldable for any application (a)
Not weldable
EN AW-Almg3/5754
EN AW-AlMg5/5019
Not weldable
Not weldable
Not weldable
Weldable within limits (b)
a. For example, for force transfer
b. For force transfer
c. Only for Drawn Arc Short Cycle process
d. Only for heat transfer
3. Up to 12mm diameter
Welding Compatibility of Materials Using Capacitor Discharge with Tip Ignition
Stud Material
Parent Materials
1.4742
1.4762
ISO/TR 15608 material groups 1-6 , 11.1
ISO/TR 15608 material groups 1-6, 11.1 and galvanised or metal coated steel sheet maximum thickness coating thickness of 25 µm
ISO/TR 15608
material group 8
Copper and Lead free copper alloys, e.g. CuZn37 (CW508L)
ISO/TR 15608
material group 8
S235
4.8
Highly weldable for any application (a)
Weldable within limits (b)
Highly weldable for any application (a)
Weldable within limits (b)
Not weldable
(weldable)
1.4301
1.4303
Highly weldable for any application (a)
Weldable within limits (b)
Highly weldable for any application (a)
Weldable within limits (b)
Not weldable
CuZn37
Weldable within limits (b)
Weldable within limits (b)
Weldable within limits (b)
Highly weldable for any application (a)
Not weldable
EN AW - AI99.5
Not weldable
Not weldable
Not weldable
Not weldable
Weldable within limits (b)
EN AW - AIMg3
Not weldable
Not weldable
Not weldable
Not weldable
Highly weldable for any application (a)
a. For example, for force transfer
b. For force transfer
Visual and Mechanical Welding Assessment Results and Corrective Actions Guidance
The below tables cover results visual and mechanical testing results for the different processes, and offer some guidance on what actions can be taken to help eliminate failures, as well as some more general information that may be helpful with weld assessment.
Drawn Arc Stud Welding with Ceramic Ferrule or Shielding Gas
Appearance & description
Assessment of
problem
Recommended
corrective actions
Notes
Visual examination or marco cross-section.
Collar regular, bright and complete. LAW correct.
Acceptable
None
The weld collar does not have to be of uniform height around the stud, but should be present around the whole circumference of the stud.​
LAW (Length After Weld) should be within tolerance, i.e. stud is NOT longer than nominal length.
Reduced diameter weld.
LAW too long.
Insufficient protrusion or lift
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Insufficient centring
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Welding power too high
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Welding time too high
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Damping too strong
In case of insufficient protrusion, the stud lacks the necessary reach to penetrate into the parent material.
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Stud should travel through ferrule without any catching up on the shoulder.
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Excessive current vaporises end of stud.
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Excessive time allows molten material to drip across the arc, cutting weld out partway through the process.
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Excess damping causing slow return to weld pool.
Increase protrusion or lift
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Check centring of stud in ceramic ferrule
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Reduce current
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Reduce welding time
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Reduce damping / disengage damper
Reduced, irregular and greyish collar. LAW too long.
Increase current/time
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Use dry ferrules
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Increase lift
Insufficient energy input to complete a good weld.​
Ferrules that contain residual moisture should not be used.
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Stud does not significantly away from weld, so lack sufficient momentum for penetration into the weld pool.
Weld power too low
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Ceramic ferrule is wet
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Lift too short
Collar off-centre with significant undercut.
Effect of arc blow
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Insufficient centring
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Stud not perpendicular during welding
Arc blow is a effect of strong magnetic fields during welding. Earth positioning needs assessment.​
Stud is likely against side of ferrule, or ferrule is not correctly seated in holder.
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During welding the stud is not perpendicular to the workpiece.
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Testing Note – when testing for acceptable undercut, bend tests must be in the direction OPPOSITE the undercut.
See guidance on earth position sections below​
Check centring of stud in ceramic ferrule
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Check operator positioning and tooling
Collar height extremely reduced, bright, large, lateral projections. LAW too short
Reduce weld current or time
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Reduce protrusion and/or check damper engagement
Too much energy input into weld​​
The return speed to the weld pool is too high. This can be caused by too much protrusion giving excessive tension on the spring in welding tool, or the damping action is not working, due to disengagement or alteration of damper position.
Weld power too high
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Plunge rate too high
Mechanical testing assessment
Plug failure in parent material
Testing Note – acceptable if plug failure is around the circumference of the stud, or if a significant amount of the cross-section of the weld area comes away with the stud, otherwise treat as weld failure.
Acceptable
None
Fracture above collar after sufficient deformation
Testing Note – acceptable after stud exceeds mechanical testing limit.
Acceptable
None
Fracture within weld area. High porosity
Insufficient energy input to complete a good weld.
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Excessive surface contamination is causing impurities to be trapped in weld area.
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Carbon content or CEV is too high, for best results use materials with a CEV of 0.25 or lower.
Weld power to low​
Unclean Surface
Material not suitable for stud welding
Increase current/time​
Clean the surface
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Select suitable material
Fracture in HAZ. Greyish fracture surface without sufficient deformation
Material hardness is too high, material not suitable for studwelding.
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Material cools too quickly post-weld, causing contraction cracking. Increase weld time to increase latent heat in material, or consider preheating/ postheating to ease cooling rates.
Hardening increased​
Cooling rate too high
Select suitable material​
Increase weld time, preheating may be required.
Fracture in weld, bright sparkling appearance.
Excessive flux creates layer of impurity in weld.​
Insufficient weld time results in flux not being fully removed during welding.
Flux content of stud is too high
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Welding time too low
Reduce flux quantity on studs
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Increase weld time
Fracture in weld area after insufficient deformation with lack of fusion in border areas
Control unit may not allow hot plunge, contact manufacturer for guidance.
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Increase protrusion.
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Excess damping causing slow return to weld pool.
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Because of the quick weld times, even brief obstructions of the tool in the shaft can result in weld failures.
Cold plunge
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Return speed too low
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Damping too strong
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Extraordinary friction
Provide hot plunge
Insufficient protrusion
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Reduce damping / disengage damper
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Ensure welding tool shaft moves smoothly and freely
Burn-through
For drawn arc processes a minimum ratio of stud diameter: parent metal thickness applies as follows;​
Drawn Arc ≤ M10 3:1
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Drawn Arc > M10 4:1
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If the above ratios are applied and burn-through is still a problem, then the weld time is too high.
Weld pool penetrates parent material
Increase parent material thickness
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Reduce energy input
Drawn Arc Short Cycle Stud Welding
Appearance & description
Assessment of
problem
Recommended
corrective actions
Notes
Visual examination or macro cross-section
Regular collar, no visual defects
Acceptable
None
Collar should be present all the way around the circumference of the stud.
Partial weld
Weld power
too low
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Polarity incorrect
Increase current/time
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Correct polarity
Energy input is to low to complete a good weld.​
Usually the handtool will be the negative electrode. Changing this will change heat distribution across the weld.
Large irregular collar
Welding time too long
Reduce welding time
Energy input to weld too high resulting in excess molten material produced during welding.
Pores in Collar
Welding time too long​
Current too low
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Oxidation of weld pool
Surface contamination
Reduce welding time
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Increase current
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Provide suitable shielding gas
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Clean the surface
Welding time too long allowing greater chance of oxidation.
Current too low to burn contaminants out of weld area, increase current or clean material.
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Select appropriate shielding gas for material.
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Excessive surface contamination is causing impurities to be trapped in weld area.
Collar off-centre with unacceptable undercut
Effect of arc blow
See guidance on earth positions section below
Arc blow is a effect of strong magnetic fields during welding. Earth positioning needs assessment.
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Testing Note – when testing for acceptable undercut, bend tests must be in the direction OPPOSITE the undercut.
Mechanical testing assessment
Plug failure in parent material
Acceptable
None
Testing Note – acceptable if plug failure is around the circumference of the stud, or if a significant amount of the cross-section of the weld area comes away with the stud, otherwise treat as weld failure.
Plug failure in parent material
Acceptable
None
Testing Note – acceptable after stud exceeds mechanical testing limit.
Fracture in HAZ
Material not suitable for stud welding
Select suitable material
Carbon content or CEV is too high, for best results use materials with a CEV of 0.25 or lower.
Lack of Penetration
Heat input
too low​
Incorrect polarity
Energy input is too low to complete a good weld.
Usually the handtool will be the negative electrode. Changing this will change heat distribution across the weld.
Capacitor Discharge Stud Welding
Appearance & description
Assessment of
problem
Recommended
corrective actions
Notes
Visual examination or macro cross-section
Small weld spatter around joint, no visual defects
Acceptable
None
Spatter should be present all the way around the circumference of the stud.
Gap between flange and parent material
Weld power too low
Return speed too low
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Insufficient parent metal support
Increase voltage
Increase spring pressure
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Provide support to underside of material
Insufficient energy input to complete weld.
Higher spring pressure makes a faster return.
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Thin material may flex if unsupported. Support material to eliminate any flex.
Considerable spatter
around weld
Weld power too high
Return speed too low
Reduce voltage
Increase spring pressure
Excessive voltage causes increase in spatter around weld.
Slower return time causes excessive material ejection from weld area.
Weld spatter off-centre with undercut
Effect of arc blow
See guidance on earth positions section below
Arc blow is a effect of strong magnetic fields during welding. Earth positioning needs assessment.
Testing Note – when testing for acceptable undercut, bend tests must be in the direction OPPOSITE the undercut.
Mechanical testing assessment
Plug failure of parent material
Acceptable
None
Testing Note – acceptable if plug failure is around the circumference of the stud, or if a significant amount of the cross-section of the weld area comes away with the stud, otherwise treat as weld failure.
Fracture of stud above flange
Acceptable
None
Testing Note – acceptable after stud exceeds mechanical testing limit.
Fracture in weld area
Weld power to low
Return speed too low
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Combination stud/parent material unsuitable
Increase voltage
Increase spring pressure
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Select suitable materials
Insufficient energy input to complete weld.
Higher spring pressure makes a faster return.
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Carbon content or CEV is too high, for best results use materials with a CEV of 0.25 or lower.
Guidance on Positions of Earth Clamps and Remedies to Effect of Arc Blow
The below table shows some situations in which arc blow is being caused and then gives some examples of how the problem may be remedied.
Cause
Remedy
Arc blow is caused by the strong electro-magnetic field established during the welding process, and causes the movement of material from the weld pool under the stud during the welding process.
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When the arc is struck, the plate material is melted and takes on the same positive charge as the earth clamps, as the earth clamps are strong positive electrodes, they repel the plate material from underneath the stud.
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The effect of arc blow is proportional to the current intensity and can be influenced by positioning of the earth clamps and by placing additional masses of metal as compensators to reduce the effect of arc blow. Arc blow causes the weld to only melt one side of the stud and creates additional porosity in the weld area, so taking appropriate measures to counteract arc blow is essential.