不同变形量5182-O铝合金汽车板PLC效应表现和吕德斯带演变

PLC Effect and Luders Band Performance of 5182-O Aluminum Alloy Automotive Plate under Different Deformation

目的系统研究变形量对5182-O合金吕德斯效应、PLC效应和吕德斯带演变的影响,为提高汽车用5182-O合金冲压零件表面质量、扩大其应用范围奠定理论基础。方法采用透射电子显微镜(TEM)、拓扑仪和万能拉伸试验机等手段表征变形时材料的位错演变、局部变形带形成、宏观形貌演变规律等。结果当材料变形量较小时,位错密度较低,呈现随机散布状态,随着变形量的增大,位错快速增殖且密度迅速增大,位错相互缠结,当材料变形发展至PLC效应临界区时,逐渐演变形成小范围位错塞积群,当材料变形发展至PLC效应深入发展区时,最终演变形成大范围位错塞积群和林位错墙,而与之相对应的材料表面的宏观形貌演变规律如下:由低变形量时的光滑表面演变为单条变形条带、多条变形条带和最终致密粗糙的变形条带。结论不同变形量对材料吕德斯效应、PLC效应、局部变形条带形成影响显著。当变形量较小时,位错密度低,位错增殖速度缓慢,吕德斯效应、PLC效应弱,材料表面无明显变形条带。而当变形量较大时,位错增殖迅速,位错相互缠结,位错与第二相、晶界交互作用,形成位错塞积群和林位错墙,PLC效应剧烈,变形不均,导致表面形成变形条带。

The work aims to systematically study the influence of deformation on Luders effect,PLC effect and Luders band evolution of 5182-O aluminum alloy,to lay a theoretical foundation for improving the surface quality of automotive 5182-O al-loy stamping parts and expanding its application range.The dislocation evolution,local deformation zone formation and macro-scopic morphology evolution were characterized with a transmission electron microscopy(TEM),a topometer and a universal tensile testing machine.When the material deformation was small,the dislocation density was low,showing a random scattering state.With the increase of the deformation,the dislocation rapidly increased and the density increased rapidly,and the disloca-tion became entangled with each other.When the material deformation developed to the critical zone of PLC effect,the disloca-tion plug group gradually evolved into a small range.When the material deformation developed to the deep development zone of PLC effect,a large range of dislocation plug groups and forest dislocation walls were finally formed,and the corresponding macro-morphologic evolution of the material surface was as follows:the smooth surface with low deformation changed to a sin-gle deformation strip,multiple deformation strips and finally dense and rough deformation strips.The different deformation amount has significant influence on the Luders effect,PLC effect and local deformation strip formation.When the deformation amount is small,the dislocation density is low,the dislocation proliferation rate is slow,the Luders effect and PLC effect are weak,and there is no obvious deformation strip on the surface of the material.However,when the deformation is large,the dis-location proliferation is rapid,the dislocation entangles with each other,the dislocation interacts with the second phase and the grain boundary,forming the dislocation plug group and the forest dislocation wall.The PLC effect is severe,and the deforma-tion is uneven,resulting in the formation of deformation bands on the surface.