工业化制备7050铝合金厚板显微组织与力学性能

摘要

采用OM、TEM观察、室温拉伸试验,研究工业化制备大截面7050铝合金厚板微观显微组织和力学性能.结果表明:板材表层、1/4厚度层和芯部处均存在部分粗大晶粒组织以及晶粒尺寸分布不均匀现象,其中芯部粗大晶粒的尺寸、数量以及晶粒尺寸不均匀程度均高于1/4厚度层和表层;合金时效后晶内的析出相主要为η'相、η相以及少量GPⅡ区,表层晶粒内的析出相密度大于1/4层和芯部,且1/4层和芯部粗棒状的η相含量较高;合金的强度、硬度以及延伸率在厚度方向上呈梯度分布,表层硬度、抗拉强度(σb)、屈服强度(σ0.2)和延伸率(δ)均最高,从表层到芯部,硬度、σb、σ0.2以及δ均逐渐减小.%The microstructure and tensile property of industrially prepared 7050 aluminum alloy thick plate were investigated by means of optical microscopy (OM),transmission electron microscopy (TEM) and tensile test.The distribution of grain size in the alloy was uneven,with parts of coarse grains.The size and quantity of coarse grains and the degree of grain size inhomogeneity in the central layer were higher than those in the surface and quarter layer.After the two-step aging,the main precipitation phases of the alloy were η phase,phase and a small amount of GP Ⅱ region.Discontinuous precipitation and precipitation free zone (PFZ) was found in the grain boundaries.The precipitation density in the surface layer was greater than that in the quarter and center layer.The gradient distribution of the hardness and tensile properties along with the thickness direction were found.The strength,hardness and elongation in the surface were higher than those in the quarter and center layer.