Effect Of Compound Magnetic Field On Solidified Structure And Mechanical Properties Of AZ31 Magnesium

Magnesium alloy plays an irreplaceable role in automobile,weapon,medical device and other industries.Magnesium alloy is based on magnesium and has abundant resources on earth.China is great power of magnesium resources,which is of great significance for the utilication of magnesium alloy.In order to improve the limitation of crystal structure and slip system of magnesium alloy,refining so lidification structure is a common method to improve the comprehensive properties of magnesium alloys.As the average grain size decreases,the strength of the alloy increases and the plasticity increases.In the industrial application,due to the low price of AZ31 magnesium alloy resources,it is easy to improve its strength and improve its ductility and it is widely used in many structural materials.The key to the wide application of magnesium alloys is the control of the solidification process.Pollution-free,easy to operate,effective magnetic field treatment,more and more attention.Therefore,in this article,the experimental material is AZ31 magnesium alloy,and the influence of three different processes of pulse magnetic field,a magnetic field and compound magnetic field on the solidification structure of alloy was studied.Moreover,the effect of three processes on solidified structure and mechanical properties of AZ31 magnesium alloy was compared,research results show that:1)Solidification structure of AZ31 alloy can be improved significantly by pulsed magnetic field treatment.With the increase of pulsed voltage(0?300V),pulsed frequency(1?10Hz),or pouring temperature(660??750 ?)primary phase of the alloy degrades gradually from well-developed dendrites into fine equiaxed grains or rosette crystals.Mould temperature(20??600 ?)Primary grain size is refined firstly and then coarsened.The inflection point is 200 ?.pulsed magnetic field can be obvious improve compression performance of AZ31 Alloy.When the pulsed voltage is 300 V,pulsed frequency 5 Hz,pouring temperature is720?.mould temperature is 200 ?,the Compressive stress reach 340.87MPa.Compared with conventional cast,compressive stress and compressibility of the alloy are increased by up to71.40%and75.14%,respectively.2)Under the action of alternating magnetic fields,with the increase of alternate voltage(0?250V),primary grain size is refined firstly and then coarsened.the detailed effct is best when the acvoltage is 200V,the primary phase is transformed from a developed dendrite into an equiaxial crystal or rosette gain;mould temperature(20 ??600?),primary grain size is refined firstly and then coarsened,when the temperature is 200 ?,the grain size is the smallest;pouring temperature(660??750 ?),With the increase of pouring temperature,primary phase is transformed from a developed dendrite into an equiaxial crystal or rosette gain;when the temperature is 750 ?,the primary phase ?-Mg grain is further refined,and most of it is transformed into spherical crystals;Alternate magnetic field can be obvious improve compression performance of AZ31 Alloy.When the alternate voltage is 200 V?pouring temperature is720 ??mould temperature is 200 ? the Compressive stress reach 251.59MPa,compressibility is 28.78%;the compressive strength of conventional casting was 199.15 MPa,and the compression ratio was 21.321%,Compared with conventional cast,compressive stress and compressibility of the alloy are increased by up to26.33%and 34.98%,respectively.3)Compared to conventional casting,the pulsed magnetic field treatment or alternate magnetic field treatment can reduce the grain size from 3.5mm to 1.1mm or 1.5mm,but compound treatment could reduce to 0.93mm;the pulsed magnetic field treatment or alternate magnetic field treatment can improve the transect isometric grain size from 55.8%to 76.3%or 69.2%,but compound treatment could improve to 97%;When the mould temperature is at 20?600 ?,With the increase of mould temperature,solidified structure is refined firstly and then coarsened.The knee temperature is 200 ?.Meanwhile,Effects of mechanical properties by compound treatment is the best of the three magnetic field treatment;The grain size was larger when the pulse voltage was 0V in the compound magnetic field,and the grain size was the smallest at 300V.The higher the voltage is,the smaller the grain size is.At the same time,the frequency of pulse is higher in 1?10Hz,and the grain size is smaller.The tensile strength of alternating magnetic field was 150.74Mp and the elongation rate was 9.2%;the tensile strength of the pulsed magnetic field was 173.01Mp and the elongation rate was 9.31%;the tensile strength of compound treatment field was 182.46Mp and the elongation rate was 10.53%;Compared with conventional cast,the tensile strength of alternating magnetic field increased by 12.42%and the elongation increased by 15.94%;the tensile strength of the pulsed magnetic field increased by 29.02%and the elongation increased by 23.67%;tensile strength and elongation of the compound treatment are increased by up to35.8%and 25.6%,respectively.