A re-welded ladder rung failed on a tractor trailer and a metallurgical failure analysis was requested. An overall view of the failed truck ladder is shown in Photograph A.
Photograph A Ladder failure on grain truck.
The failure was the result of metal fatigue. Visual and microscopic inspection revealed that the ladder and a variety of components had been re-welded numerous times. These facts indicated that the truck had been subjected to significant vibration stresses while driven on "washboard" roads within the company facilities. The truck manufacturer was found to have produced adequate welds when the truck was originally manufactured. Close-up views of welding cracks are shown in Photographs B and C.
Photograph B Weld cracking resulting from metal fatigue
Photograph C Weld cracking resulting from metal fatigue