. Electron microscopy; proceedings of the Stockholm Conference, September, 1956. Electron microscopy. Fig. I. Initiation of Wear Damage on Soft Steel. An area of running track near the start of a test run. Tiie material of the cylinder is steel of hardness aproximately 200 Plastic deformation of this fairly ductile material is evident, also small areas of surface damage produced by the displacement of material. Magnification 7500. Fig. 2. Initiation of Wear Damage on Hard Steel. Initial damage to the surface of a case hardened E. steel cylinder of hardness over 800 The
. Electron microscopy; proceedings of the Stockholm Conference, September, 1956. Electron microscopy. Fig. I. Initiation of Wear Damage on Soft Steel. An area of running track near the start of a test run. Tiie material of the cylinder is steel of hardness aproximately 200 Plastic deformation of this fairly ductile material is evident, also small areas of surface damage produced by the displacement of material. Magnification 7500. Fig. 2. Initiation of Wear Damage on Hard Steel. Initial damage to the surface of a case hardened E. steel cylinder of hardness over 800 There is little plastic deformation of this hard material of low ductility and initial damage appears to be by displacement of material and cracking following overstressing of the surface. Magnification 6000. Visual damage by optical microscopic examina- tion after only one revolution of the wear machine appeared to be confined to circumferential scratches, but from the electron micrograph it appeared that, within each individual scratch, plastic flow had oc- curred over a narrow track and a step-wise structure had been formed suggesting a stick-slip method of formation. It is not to be expected that the complex mecha- nism of wear should be easily elucidated for the very process itself eliminates its own initial stages as cumulative action develops towards catastrophic failure. For the study of factors initiating such a failure it is desirable that a single traverse be made of a surface so that the development of surface failure may be followed. For this purpose a special crossed-cylinder machine (1) has been developed at the Mechanical Engineering Research Laboratory in which one cylinder is rotated and a mating cylin- der, at right angles, so traversed that the zone of contact moves along the surface of both cylinders and fresh contact surfaces are continually being presented. The helical track round the cylinder reveals how the damage to the surface builds up with increase of
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