Research On The Superplastic Bulging Control Mechanism Of Aluminum Alloy Based On The Maximum M

In cold forming condition, the plasticity of aluminium alloy is poor, forming isvery difficult, and the superplastic forming can effectively solve the problem.Therefore, the majority of scientific research personnel have conducted the extensiveresearch on the superplastic forming technology of aluminum alloy, however, thesestudies are based on the traditional research methods, such as the constant velocityand the constant strain rate method. It is well known that the strain rate sensitivityindex m value is one of the important indicators to evaluate the superplasticity ofmaterial, the value is the greater, the superplasticity of materials is better, so, thisarticle firstly uses the maximum m method to explore the mechanical properties ofaluminum alloy, and a new method of optimum strain rate superplastic bulging basedon the maximum m method is putted forward, and that has the vital significance forfurther studying and the superplastic forming technology of aluminum alloy forreference.First of all, the uniaxial tensile experiments were conducted by using the methodof the maximum m, the method of the constant velocity and the method of theconstant strain rate, for researching on the mechanical properties of5083,2A12aluminum alloy. The results show that the deformation temperature of5083aluminumalloy was525℃, the largest elongation was331%, and had certain superplasticity;Compared with the tensile method of the constant velocity and the constant strain rate,the tensile method based on the maximum m value, not only improved the elongation,and had also reduced the time, in addition, the different rolling direction led toanisotropy of the material, had obvious effects on the superplasticity of5083aluminium alloy; The best deformation temperature of2A12aluminum alloy was450℃, the maximum elongation was121.4%, also had certain superplasticity, the K andm of the constitutive model parameter were respectively119.95and0.344at450℃;The strain rate-true strain curve of2A12aluminum alloy based on the maximum mvalue tensile experiments was optimized, got the curve of optimized bulging strainrate at the best superplastic bulging deformation temperature, provided the basis forthe finite element simulation.Combined with the direct-reverse bulging process, the superplastic bulging of fairing shell was simulated by using the optimized strain rate curve based on themaximum m method. The results show that: compared with the constant strain ratebulging, the optimized strain rate bulging based on the maximum m method cangreatly improve the efficiency of bulging; Compared with unidirectional bulgingprocess, the direct-reverse bulging process can not only reduce material thinning rate,and can effectively improve wall thickness uniformity; According to the results offinite element simulation of superplastic bulging, the bulging die has been optimized,and get the pressure control curve of the optimized strain rate bulging based onmaximum m method.The superplastic bulging experiment of fairing shell was carried on by using thepressure control curve of the optimized strain rate bulging based on maximum mmethod. The results showed that: the forming quality is good, the efficiency ofbulging is high, and the uniformity of wall thickness has been effectively improved, atthe same time, the results of the simulation are agreed well with the experimentalresults.