| Mg Alloy has poor plasticity at room temperature. The mature production technology of Mg alloy sheet mainly includes break-down hot-rolling and break-down extruded-rolling, which have cumbersome processes and are limited by high temperature and high cost. While continuous cast-rolling is a new kind of developing technology, especially the application of external energy-field during the cast-rolling process, which is a kind of efficient, energy-saving and short process, can improve comprehensive properties of the alloy. The microstructure and texture are the critical factors affecting the comprehensive properties of Mg alloy. In order to find the efficient and low-cost preparation method of Mg alloy sheet with high performance, the paper studied on the evolution of textures and properties of the three kinds of AZ31B Mg alloy sheets through a series of relative experiments. The specimens were deformed by hot-rolling, general cast-rolling and electromagnetic ultrasonic energy-field cast-rolling. The main works and conclusions in this paper are as follows:(1) The effect of electromagnetic and ultrasonic energy-field on cast-rolling sheet shows that under the effect of electromagnetic and ultrasonic energy-field, the original microstructure of cast-rolling sheet is obviously refined and homogenized, the original texture intensity of it is also reduced and the preferred orientation of it is weakened.(2) Comparative analysis of the three kinds of Mg alloy sheets rolled by subsequent multiple passes at250℃shows that the successive dynamic recrystallization of electromagnetic and ultrasonic Mg sheet arise at the fourth pass and the fifth pass. In terms of general Mg sheet, that of the electromagnetic and ultrasonic Mg sheet is advanced by one pass. In comparison to hot-rolling Mg sheet, that of the electromagnetic and ultrasonic Mg sheet is advanced by three passes. The minimum grain size (4-6μm) of the electromagnetic and ultrasonic Mg sheet was obviously less than that (8-10μm) of the general Mg sheet and that (10-12μm) of the hot-rolling Mg sheet. In comparison to general Mg sheet, the intensity of main texture, basal plane texture, of electromagnetic and ultrasonic Mg sheet increases more rapidly in the previous three rolling processes and increases more slowly in the following four processes. With the advantage of grain size and texture, the yield strength, ultimate tensile strength and elongation of the electromagnetic and ultrasonic Mg sheet are higher than the general one respectively. Furthermore, the anisotropy of it is weaker than the general one.(3) The effect of annealing on the ultimate rolled Mg sheets shows that the process of static recrystallization of electromagnetic and ultrasonic ultimate rolled sheet is completed after annealing at the temperature of200℃, which is lower about50℃than that of the general ultimate rolled sheet and the hot-rolling ultimate rolled sheet. Furthermore, the Al and Zn of precipitates of the electromagnetic and ultrasonic ultimate rolled sheet diffuse into matrix most quickly and the distribution of precipitates of it on grain boundary is the most dispersed among the three kinds of ultimate rolled sheets.(4) The study on stamping performance of the ultimate rolled Mg alloy sheets shows that compared to general ultimate rolled sheet, the maximum limiting drawing ration (2.00) and Erichsen (2.95) at room temperature of electromagnetic and ultrasonic ultimate rolled sheet are respectively improved by7.0%,16.1%. Compared to hot-rolling ultimate rolled sheet, the maximum limiting drawing ration and Erichsen of electromagnetic and ultrasonic ultimate rolled sheet are respectively reduced by only6.5%,8.1%. Chart:74; table:9;reference:87... |
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