J. Cirne, R. Dormeval, et al.
J. Phys. IV France 134 (2006) 1313-1318
Microstructure of surface zones subjected to high-velocity parting-offK. Ryttberg1, M. Knutson Wedel1, P. Dahlman2 and L. Nyborg1
1 Department of Materials and Manufacturing Technology, Chalmers University of Technology, 412 96 Gothenburg, Sweden
2 SKF Sverige AB, 415 50 Gothenburg, Sweden
Published online: 26 July 2006
A hydraulic high-velocity pressing machine with a parting-off tool was used for adiabatic cutting with impact velocities ranging from 5 to 10 m/s. In this study the associated fracture mechanisms and microstructures of three different materials (100Cr6, 100CrMn6 and C56) in the form of wire or bar were investigated. It was concluded that the parting-off is initiated through a shearing effect resulting in ductile shear fracture being responsible for the cutting. In all of the samples microcracks were found in the severely deformed region around the cut, which became larger with increasing sample diameter. Evidence of heating was not observed in the cut zone of samples having 6 mm diameter. However, for samples with a diameter of 70 mm and above, a white-etching band could be found, indicating that the temperature had increased considerably in this region. Analysis of the fracture surfaces using scanning optical microscopy showed that the fracture mode had mostly been ductile shear, with exception of the largest samples where some evidence of tensile fracture could be observed.
© EDP Sciences 2006