Forming Cracks on Stainless Steel Wire

Cold-drawn type 303 stainless steel wire sections, 6.4 mm (0.25 in.) in diameter, failed during a forming operation. All of the wires failed at a gradual 90 deg bend. Investigation (visual inspection and 5.3x/71x/1187x SEM views) supported the conclusion that the wires cracked due to ductile overload. The forming stresses were sufficient to initiate surface ruptures, suggestive of having exceeded the forming limit. Recommendations included examining the forming process, including lubrication and workpiece fixturing.