Effect of pulsed magnetic field pre-treatment of AISI 52100 steel on the coefficient of sliding friction and wear in pin-on-disk tests

Disc specimens manufactured from commercial bearing rollers (AISI 52100 steel, 62–63 HRC) in initial state and after pre-treatment by pulsed magnetic field (PMF) with a magnetic field strength of 1–7 MA/m were tested with sunflower oil using pin-on-disk apparatus. According to the obtained results the treatment causes a reduction in the coefficient of friction and wear. To explain the results, nano- and microhardness tests as well as optical and atomic force microscopy were used. Reasons of the effect of PMF on the friction and wear were discussed.Peer reviewe

Wear Process Description Based on Acoustic Emission

Since acoustic emissions are generated by fundamental mechanical processes, they can provide insight into the basic processes which determine friction and wear behavior. Descriptions Introduction When the mechanical state of a material body changes, energy is released, and some of it goes into the formation of transient stress waves called acoustic emission (AE). The surface displacements that occur when the AE interact with material surfaces are easy to measure using a displacement sensor mounted on the surface. These measurements provide a signal related to the AE and hence to the physical process which generated it. The ease of AE measurements and the possibility of relating them to the fundamental mechanical processes of deformation, fracture, and structural and compositional changes are strong incentives for the use of AE monitoring in material behavior characterization. In the tribological setting, AE measurements have two general uses. One is in basic studies of the mechanical processes giving rise to friction and wear. The goal is to relate signal characteristics to basic mechanical processes and so gain a detailed understanding of friction and wear. Another general use of AE monitoring is in the continuous assessment of material and machinery states. Material and interface monitoring is useful for performance measurement and condition monitoring. Two difficulties arise in AE monitoring. In almost all applications, the AE generation site and sensor location are widely separated. The transmission of the AE through the intervening material results in attenuation and, in extreme cases, such as transmission through material interfaces, in a change in form of the AE. More specific to tribological studies are complications in AE signal interpretation which may arise due to the high AE generation rates expected. Typically, friction and wear occur over an extended volume, and the rates of the processes are high. The result is that the individual transient stress waves generated interact with a large number of other AE and lose their distinct identity and characteristics. Signal interpretation then becomes a problem