Metallurgical examination and failure analysis was requested of a barstool that collapsed while being used in a retail location. The person seated on the barstool was severely injured. An overall view of the failed barstool, with the front left leg missing is shown in Photograph A.
Photograph A Failed barstool with missing front left leg.
An overall view of the bottom side of the barstool is shown in Photograph B. The location of a failed fillet weld used to connect the barstool foot ring to one of the four legs is denoted with a white arrow.
Photograph B Arrow denotes location of failed fillet weld.
A close-up view of the failed foot ring to leg fillet weld is shown in Photograph C. Note the straight edge of the fillet weld, denoted with arrows, which attached the foot ring to the barstool leg. The straight edge of the failed weld indicates lack of weld penetration into the barstool leg.
Photograph C Failed foot ring to leg fillet weld.
The underside of the weld on the barstool leg of failed fillet weld, is shown in Photograph D. Visual and microscopic examination revealed massive weld porosity. A close-up view of the area where the fillet weld was designed to attach the foot ring to the barstool leg is shown in Photograph E. White arrows indicate a heat effect from attempted welding, but total lack of weld penetration.
Photograph D Underside of foot ring to leg fillet weld showing weld porosity.
Photograph E Bar stool leg showing lack of weld penetration.
For reference purposes, a properly and adequately welded leg to foot ring joint is shown in photograph F.
Photograph F Properly welded leg to foot ring joint.
The failure of the subject barstool was the result of poor welding and lack of weld penetration between the bar stool ring and the barstool leg. Massive weld porosity was a symptom of defective, improper and inadequate welding.