Research On Warm Compression Deforming Behavior Of AZ31Magnesium Alloy

In this paper, single-pass compression and multi-pass compression experiment ofAZ31B magnesium alloy have been tested by Gleeble-3800Thermal Simulated TestingMachine, studied the influence rule of deforming temperature, strain rate anddeformation quantity on stress-strain behavior，microstructure and micro-hardness ofAZ31B magnesium alloy, and established the constitutive equation of AZ31Bmagnesium alloy plastic deformation in the experiment temperature range. By annealingexperiments, we have studied the microstructure changing of AZ31Bmagnesium afterhot compression deformation in different annealing temperature. By AZ31B magnesiumalloy sheet rolling experiments, we have studied warm rolling process of AZ31Bmagnesium alloy sheet in the actual production. From the experimental analysis andresults showed that:(1)We find the changed of temperature, strain rate and deformation quantity have anobvious influence to the stress-strain relationship, microstructure and micro-hardness ofAZ31B hot compression specimen. Under certain conditions, the deformation resistancedecline with the temperature increasing, the degree of recrystallization continues toimprove, micro-hardness decreased. With the strain rate increasing, the deformationresistance increases, microstructure finer, grain distortion will increase, organizationaluniformity will decline, micro-hardness increases. The strain rate and deformationquantity have more obvious influence on lower temperature.(2)We established the constitutive equation among flow stress, strain rate anddeforming temperature of AZ31B magnesium alloy warm compression. It can beexpressed as: (3) The temperature of AZ31B magnesium alloy multi-pass on warm compression can be controlled between180℃-260℃, the strain rate control between0.5to1.5s-1, the pass deformation should be about10%, the deformation passes should be about four times, the total amount of deformation controlled at about35%.(4) The micro structure of single-pass compression sample effect by annealing temperature is larger than multi-pass compression. It take a greater impact to the sample micro structure which deforming temperature is below220℃with220℃annealing, have little impact to that deforming temperature is up to220℃. With deformation increased, the micro structure is finer after annealing.(5)It have got4mm and2.5mm AZ31B magnesium alloy sheet which have good surface quality and a little edge cracking through hot-rolled and warm-rolled. The mechanical properties of warm-rolled2.5mm sheet are as follows:tensile strength σm is330MPa, yield strength σ0.2is275MPa, elongation rate is9.0%. Its elongation rate can reach to20.9%after250℃annealing, the average grain size up to5.2μm.(6)The deforming process and its results of AZ31B magnesium alloy are decided by the combined effects of various factors. It is very important that get appropriate deformation conditions in process of magnesium alloys deforming. When formulate deformation process and parameter of AZ31B magnesium alloy, we must consider the combined effects of the main factors, but also need to consider carefully about other factors.