【摘要】 屈服强度对零部件的冲压变形有着极大的影响，而吕德斯带则严重影响零部件美观，可以通过拉伸实验中的屈服点延伸率评估吕德斯带严重程度。利用拉伸试验机、金相显微镜、电导率仪等设备，研究了晶粒尺寸与Mg原子存在状态对5754铝合金板材的屈服强度与屈服点延伸率的影响。当板材晶粒尺寸介于16～26μm时，随着晶粒尺寸增大，板材屈服强度降低，屈服点延伸率减小，板材屈服强度与晶粒尺寸d^-1/2呈线性关系，而板材屈服点延伸率与晶粒尺寸d呈线性关系。通过改变板材退火后的冷却速度调整Mg原子存在状态，当冷却速度变慢时，Mg原子容易形成Cottrell气团，使板材屈服强度提高，屈服点延伸率增大。更多还原

【Abstract】 The yield strength has a significant impact on the stamping deformation of parts, while the Lüders band severely affects the appearance of parts, which can be estimated by the yield point elongation in tensile tests.The effects of grain size and Mg atomic state on the yield strength and yield point elongation in 5754 aluminum alloy were investigated by tensile testing machine, metallographic microscope, and conductivity meter. With the grain size increased, both of the yield strength and yield point elongation decreased, in the range of 16-26 μm. The yield strength shows a linear relationship with the grain size d to the power of-1/2, while the yield elongation shows a linear relationship with the grain size. The different cooling rates after annealing changed the states of Mg atoms in matrix. When the cooling rate became slower, the pinning effect of Mg atoms became stronger, forming more Cottrell atmospheres. This leads to increasing of yield strength and yield point elongation.更多还原