Experiment On Grinding Hardening Effect Of 48MnV Micro-alloyed Steel

Grinding-hardening process is a new kind of technology to quench, which makes use of the heat produced during grinding. This technology can combine grinding process and surface quenching, which leaves out the induction quenching process. Accordingly energy is saved, production process is predigested and the heat produced during grinding is fully and efficiently used.This paper firstly takes the 48MnV steel as research object which is used to produce bent axles of motorcars. With grinding wheel of corundum, examinations are taken on flat surface grinding machine of MMD7125. On different grinding parameters and cooling condition, the temperature curve of grinding-hardening is attained by using the technology of measuring temperature with half artificial thermocouple. The microhardness of grinding-hardening layer is measured by the instrument of HSX-1000. The photos of microstructure are shot on electron microscope of MM6 with digital camera. The effect and mechanism of grinding-harden are also discussed.The results indicate those facts as follows. By optimizing parameters, the necessary grinding-hardening conditions are achieved such as warming up rate, highest temperature, action time of temperature and cooling rate. The microstructure and effect of hardening get from grinding-hardening is better than the one get from induction quenching. The microstructure of entirely hardening layer is much more subtle needle-type martensite whose microhardness is more than HV800. The depth of entirely hardening layer could reach 1.2mm. The microstructure, microhardness and depth of grinding-hardening all meet the need of surface quenching.There is a fact should be specially emphasized. By the means of controlling the parameters of grinding-hardening such as grinding wheel topography, dosage condition and cooling condition, accordingly with the controlling of coupling interaction between temperature field and mechanical stress field, this test gains the super strengthening layer whose microhardness reaches more than HV4094.5. The layer is hard but not crisp. It behaves good plasticity and tenacity. The mechanism for further investigation is suggested.