Using manganese-sulfide inclusions for localized strain measurements in machining 1144 steel
University of New Brunswick
The following research compares and discusses the results of two series of orthogonal cutting tests of AISI 1045 and AISI 1144 steel, two common alloys in both industry and academia. The focus of these tests was on cutting forces, shear angles and the strains associated with metal cutting. The cutting tests were performed on a CNC lathe to compare the two materials and a quick-stop device in order to study the resulting chip-roots. A custome built quick-stop device was developed in order to study zones of deformation in metal cutting which was based on a equal channel angular press. The device had the benefits of quick set-up times between cutting tests, utilized small samples and was a true representation of orthogonal cutting. In order to validate the resulting cutting speeds and forces, the device was mounted to a force dynamometer. The novel design of this device was able to produce a stopping distance of 2.2 μm or a stopping time of 0.83 μs, an order of magnitude smaller than any experimental work published. The microstructure of 1144 steel lends itself to the study of localized strains in metal cutting. By monitoring the size and shape of the manganese-sulfide inclusions, localized strains were calculated and found to have an average value of 6, with strains as high as 10. Comparably, the general strain calculations based on continuous chip formation produce an average strain of 2.5. From the findings, metal cutting cannot be assumed as a bulk deformation process.