2002 年 42 巻 9 号 p. 1049-1055
This paper deals with the influence of the manufacturing process on the microscopic fracture behaviour of axisymmetric notched specimens of pearlitic steels with different degrees of cold drawing. To this end, samples from different steps of the manufacturing chain were obtained, from the initial hot rolled material (not cold draw at all) to the final prestressing steel (heavily cold drawn). A detailed fractographic analysis was performed by using scanning electron microscopy and image analysis techniques, in order to define and measure the fracture process zone in each case (final aim of this paper). Results show that the microscopic fracture modes range from ductile micro-void coalescence to brittle cleavage, depending on the stress triaxiality generated in the vicinity of the notch tip. A special fibrous region was detected, which al-lows a definition of the fracture process zone as the central region of the fractured area in bluntly notched samples and the external ring (i.e., the notch tip) in sharply notched specimens.
