均匀化处理对2A12铝合金组织及性能的影响

Effect of Homogenization Treatment on Microstructure and Properties of 2A12 Aluminum Alloy

为了获得力学性能优良的2A12铝合金并提高其合金化铣表面质量,综合采用差热分析(DSC)、扫描电镜(SEM)、透射电镜(TEM)、室温拉伸及表面粗糙度分析等测试方法,研究2A12铝合金均匀化对组织演变、析出行为、T6态合金化铣表面质量及力学性能的影响。结果表明:合金铸锭中存在的非平衡结晶相为S相、θ相及高熔点AlCuFeMn相,均匀化后晶界上残留第二相对合金化铣表面质量有重要影响;合金经495℃/12 h+505℃/18 h双级均匀化处理后,大量非平衡结晶相回溶基体,T6态组织中强化相S相呈片状析出密集分布,T相呈棒状弥散分布;获得最佳的合金均匀化制度为495℃/12 h+505℃/18 h,合金T6态化铣表面粗糙度为(1.18±0.06)μm,抗拉强度、屈服强度及延伸率分别为(469±3.5)MPa、(396±4.8)MPa和(11.8±0.1)%。

In order to obtain excellent mechanical properties and improve the quality of milling surface,the effect of homogenization of 2A12 aluminum alloy on microstructure evolution,precipitation behavior,chemical milling surface quality and mechanical properties were investigated by using diffe-rential scanning calorimetry(DSC),scanning electron microscope(SEM),transmission electron microscope(TEM),tensile,surface roughness measurement.The results show that the non-equilibrium constituent existing in the alloy ingot is the S phase,theθphase and the high melting point AlCuFeMn phase,and the residual second phase on the grain boundary affects the quality of the alloyed milling surface.After the alloy was homogenized by 495℃/12 h+505℃/18 h,a large amount of non-equilibrium constituent was dissolved back into the matrix.In the T6 alloy,the S phase was densely distributed in the form of a sheet,and the T phase was distributed in a rod shape.The best homogenization was 495℃/12 h+505℃/18 h,the milling surface roughness was(1.18±0.06)μm,and the tensile strength,yield strength and elongation were(469±3.5)MPa,(396±4.8)MPa and(11.8±0.1)%,respectively.