Abstract
Recent observations that rolling direction surface striations are generated by tensile elongation transverse to the rolling direction have cast doubt on the validity of the plastic buckling model for roping in ferritic stainless steels. Moreover, these observations are seemingly incompatible with the transverse cross section undulations which characterize the roping morphology. To clarify this situation, detailed profilometric evaluations have been performed on roping prone type 434 stainless steel strip elongated at angles of 0, 30, 45, 60 and 90 deg to the rolling direction. In all cases, light surface striations were produced parallel to the rolling direction. However, the amplitude of the characteristic cross section undulation was quite dependent on the tensile strain axis orientation. The undulation or corrugation amplitude was greatest for tensile elongation in the rolling direction and decreased as the tensile axis diverged from the rolling direction to a point where noundulations were apparent for the case of tensile elongation transverse to the rolling direction. Thus, it is concluded that the acceptibility of the plastic buckling model is not called to question by the results of tensile elongation transverse to the rolling direction and that roping, in the general sense, is not developed by such transverse elongation. The compatibility of the plastic buckling model with observed corrugation development upon 45 deg extension is demonstrated.
Published Version
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