Basic Research On The Ultrasonic Vibration-assisted Quenching Process Of Medium Carbon Steel

Magnetic field quenching is a relatively mature technology among the compound field effect quenching.And the ultrasonic vibration-assisted quenching provides a new direction for the compound effect field quenching.On the one hand,when the ultrasonic vibration is injected into the quenching medium,there will be a cavitation effect,which can enhance the stage of the quenching medium,effectively increase the cooling intensity of the quenching medium and keep the cooling uniformity.On the other hand,during the process of ultrasonic assisted molding,the energy of ultrasonic vibration can be absorbed by material and aggravate the movement of dislocation to promote plastic deformation.At the same time,the vibration can increase the activity of particles.In this paper,ultrasonic vibration with different powers was respectively injected into the workpieces during the induction hardening of AISI1045 steel and injected into the quenching liquid during integral quenching process.The influence of ultrasonic vibration on the quenching effect was researched.As for the process of directly injecting ultrasonic into the workpiece,ultrasonic vibration with different powers was injected into the bar of AISI1045.After the quenching process,the microstructure,residual stress and mechanical properties were analyzed.The results showed that the microstructure of quenching without ultrasonic vibration were mainly twins,but with ultrasonic were mainly lath martensite and little cementite precipitates.With the addition of ultrasonic vibration during quenching process,the grain size decreased,and the surface residual stress,tensile strength,the width and depth of hardened layer increased.The greater the ultrasonic power was,the more obvious the effect was.Under the same ultrasonic power,with the increase of induction heating power,the morphology of martensite became larger,and the grain size,residual compressive stress,the width and depth of hardened layer increased,while the tensile strength first increased and then decreased.As for the process of directly injecting ultrasonic into the quenching medium,at first,the suitable heating temperature was set for 840? after the AISI1045 water quenching process under different heated temperature.And then,the AISI1045 steel workpieces with small sizes(8mm×10mm×30mm)were quenched by oil which was injected ultrasonic vibration with different power,the results showed that after quenching: the martensite content increased while the troostite decreased,the hardness and tensile strength increased,but the elongation decreased.The greater theultrasonic power was,the more significant the effect was.As for the AISI1045 workpieces with large sizes((37)30mm×100mm),when the ultrasonic was injected into the water,the martensite content and the depth of hardened layer increased.The greater the ultrasonic power was,the more obvious the effect was.