200℃预拉伸对车板用5052铝合金微观组织和力学性能的影响

Effect of Pre-stretching at 200 ℃ on Microstructure and Mechanical properties of 5052 Aluminum Alloy for Car Board

基于温控拉伸成形装置,采用光学金相显微镜、透射电镜,研究了200℃成形温度下预拉伸对5052铝合金微观组织和力学性能的影响。结果表明：不同预拉伸量的5052铝合金板材主要强化相形貌以相互十字交叉的针状形态进行分布。随着预拉伸量的增加,析出相尺寸变得更大,同时试样也出现更明显的粗化现象,降低了强化效果。随着预拉伸量的增加,成形试样的拉伸强度与屈服强度方面都表现出先增加后减小,最大值发生在预拉伸3%时,此时分别为516 MPa和475 MPa。经过3%预拉伸后,断口处出现明显的韧窝断裂特点,韧窝分布较为均匀且韧窝尺寸较大。

Based on the temperature control stretch forming device, the effects of pre-stretching at 200 ℃ forming temperature on the microstructure and mechanical properties of 5052 aluminum alloy were investigated by optical microscopy, transmission electron microscopy. The results show that the mainly strengthening phase morphology of 5052 aluminum alloy sheet with different pre-stretching quantities has a mutual cross acicular form distribution. With the increase of pre-stretching, the precipitated phase size becomes larger, and the sample generates more apparent coarsening phenomenon at the same time, which reduces the reinforcement effect. With the increase of pre-stretching, the tensile strength and yield strength of forming specimens increase firstly and then decreases, which are 516 MPa and 475 MPa with the maximum value occuring in the pre-stretching 3%. After 3% pre-stretching, the obvious dimple fracture characteristics appear in fracture,and then the distribution of the dimples is uniform and the dimple sizes are larger.