Nonmetallic inclusions have detrimental effects on ductility parameters such as elongation and reduction in area obtained in tension testing. Moreover, inclusions elongated in the rolling direction cause distinct anisotropy of these parameters.

This paper gives a demonstration of how this anisotropy can be utilized to assess the effect of elongated inclusions on the ductility of steel sheet. Other factors (e.g., sheet thickness and steel strength) that also influence the ductility are eliminated by taking the difference between the values of the ductility parameters in the longitudinal (rolling) and the transverse directions. Replicate tests and methods of mathematical statistics are employed in estimating the sensitivity of the different ductility parameters to nonmetallic inclusions. Tension specimens with special forms (twice perforated and V-notched specimens) have been devised to increase the sensitivity of the ductility parameters. Reduction in area is found to be a much more discriminating parameter than elongation at fracture.