拉拔变形量对7075铝合金晶粒组织、强度和耐蚀性的影响

Effects of drawing strain on grain structure, strength and corrosion resistance of 7075 aluminum alloy

  • 摘要: 通过室温拉伸和抗剥落腐蚀实验,结合扫描电镜、电子背散射衍射和透射电镜观察等手段,系统研究了拉拔变形量对7075铝合金棒材组织和性能的影响。结果表明:随着拉拔变形量(ε)从0增加到0.58,晶粒形貌由纤维状向近似等轴状转变,合金的强度略微减小,伸长率不断增加;合金的抗剥落腐蚀性能随变形量增加先升后降:拉拔变形量为0.09时,晶粒组织主要为纤维晶,最大腐蚀深度为530 μm;拉拔变形量为0.17时,晶粒发生异常长大,平均晶粒尺寸为193 μm,断续分布的晶界析出相阻碍了腐蚀扩展,耐蚀性显著提高,最大腐蚀深度仅为386 μm;拉拔变形量为0.36~0.58时,形成细小的再结晶晶粒(34~53 μm),大角度晶界比例上升且晶界析出相粗化,导致抗剥落腐蚀性能降低,腐蚀深度约为600 μm。

     

    Abstract: The effect of drawing strain on the microstructure and properties of 7075 aluminum alloy using tensile and exfoliation corrosion tests was investigated, combined with Scanning Electron Microscopy (SEM), Electron Backscatter Diffraction (EBSD), and Transmission Electron Microscopy (TEM) analysis. As the drawing strain (ε) increased from 0 to 0.58, the degree of recrystallization continuously increased, and the grain morphology transformed from fibrous to approximately equiaxed; The strength decreased slightly while the elongation improved continuously. The exfoliation corrosion resistance initially improved and then deteriorated with increasing deformation. At a drawing strain of0.09, the grain structure remained fibrous, leading to the maximum corrosion depth at 530 μm; At a drawing strain of 0.17, abnormal grain growth occurred, and discontinuously distributed grain boundary precipitates hinder corrosion propagation, enhancing resistance, so that the maximum corrosion depth was only 386 μm; At drawing strains of 0.36~0.58, fine recrystallized grains (34~53 μm) formed, more high-angle grain boundaries appeared, and grain boundary precipitates coarsened, leading to reduced corrosion resistance with a corrosion depth of 600 μm.

     

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