Discontinuity
Excessive reinforcement
A weld face built up far higher than the joint needs, producing an abrupt change of section at the toes that concentrates stress despite the extra metal looking like extra strength.
What it looks like
- A tall crowned cap standing well proud of the base metal surface
- Steep toe angles where the bead meets the plate almost at a step
- In fillet welds the equivalent is a heavily convex face standing above a straight line across the legs
- On film, a lighter band along the weld where the extra thickness absorbs more radiation
Causes
- Travel speed too slow for the deposition rate, piling metal into a short length
- Too many fill passes or a cap pass added when the joint was already full
- Current too low for the wire feed speed in wire processes, giving a cold, high, ropey bead
- A mistaken belief that more weld metal always means a stronger joint
- Poor weave technique that heaps metal at the centre instead of spreading it across the joint
Prevention
- Match travel speed to deposition rate so each pass lays a flat, evenly spread bead
- Plan the pass sequence for the joint volume rather than adding passes until it looks full
- Set voltage and wire feed speed together so the bead wets out instead of stacking up
- Dress excessive crowns by blending the toes smoothly rather than grinding the cap flat
How it is found
- VT
- A weld reinforcement or fillet gauge reads the height above the plate surface directly and is the primary tool for this discontinuity.
- RT
- Extra thickness shows as a lighter band and can also mask smaller internal indications by reducing overall film contrast.
- UT
- A crowned cap interferes with probe contact and beam entry, so excessive reinforcement can compromise the examination as well as the joint.
How inspectors think about it
- Assessment centres on the height above the adjacent surface and on how sharply the toes transition, since the abrupt geometry, not the added metal, is the problem.
- Fatigue-loaded and cyclically loaded joints are judged more strictly, because a steep toe angle is where a fatigue crack finds its easiest start.
- Inspectors also consider whether the crown will interfere with later examination or with mating parts, which can make a technically minor profile issue a practical failure.
General reasoning only. The accept/reject limits for your work come from the code or specification governing the job, which this site does not reproduce.
Related discontinuities
UnderfillA groove weld whose face or root sits below the surface of the adjoining base metal, so the joint has less cross-section than the surrounding material it is supposed to match.UndercutA groove melted into the base metal at the weld toe and left unfilled by weld metal, reducing the section of the parent material and leaving a sharp notch exactly where stress concentrates.OverlapWeld metal that has rolled over the toe and sits on unmelted base metal, forming a lip with a sharp crevice underneath that carries no load and hides an unfused interface.Incomplete fusionWeld metal that lay against the joint face or a previous bead without melting into it, leaving a tight unbonded plane that carries no load even though the joint looks completely filled.
Can you name it on sight?
The gauge trainer's identification mode shows you a weld and four names. Reading about porosity and picking it out of a line-up are not the same skill.