Abstract: Electromagnetic, ultrasonic and the ultrasonic electromagnetic combination field is introduced into the experiment of horizontal twin-roll casting AZ31B magnesium alloy strip to improve its mechanical properties. The influence of electromagnetic, ultrasonic and the ultrasonic electromagnetic combination field treatment on the microstructure and the mechanical properties of the magnesium alloy strip is investigated by using Leica DMI 5000 M metallurgical microscope, CSS-44100 electronic testing machine and HV-1000 hardness tester, etc. Results of the tests show the distinct improvement on microstructure and the mechanical properties of the electromagnetic, ultrasonic and the ultrasonic electromagnetic combination field treated AZ31B strip. The general, electromagnetic, ultrasonic and the ultrasonic electromagnetic combination field cast-rolling AZ31B strip average grain diameter is 120 µm, 25 µm, 27 µm and 15 µm, separately. The tensile strength, yield strength, elongation and hardness of the electromagnetic treated AZ31B strip are increased by 15.7%, 24.8%, 22.7% and 66.6%, ultrasonic treated AZ31B strip are increased by 13.8%, 26.2%, 11.4% and 13.4%, the ultrasonic electromagnetic combination field treated magnesium alloy strip are increased by 17.1%, 27.8%, 31.8% and 73.8%, separately, than that of the general strip. Electromagnetic, ultrasonic and ultrasonic electromagnetic combination field cast-rolling process enhances the mechanical properties and refines microstructure of AZ31B. At the same time, the effect mechanism of grain refinement during cast-rolling process with ultrasonic cavitation and electromagnetic field effect are discussed and analyzed.

Key words: AZ31B, Electromagnetic, Mechanical properties, Ultrasonic, Ultrasonic electromagnetic combination