论文部分内容阅读
采用金相显微镜(OM)及扫描电镜(SEM)对2D70铝合金的半连续铸锭的不同位置铸态凝固组织及其热形变后的组织进行了观察,并采用X射线衍射物相分析(XRD),能谱分析仪(EDS)对合金在凝固过程中的形成相进行了分析,对经过不同热形变工艺及淬火时效处理后的棒材进行了力学性能检测。结果表明,2D70铝合金凝固组织为典型枝晶结构,铸锭从心部到外部晶粒逐渐变细小,等轴倾向逐渐增加,沿晶界析出物逐渐增加。典型铸态组织为α(Al)、灰色蜂窝状S(Al2CuMg)、褐色针状Al7Cu2Fe和棕色条状或片状Al9FeNi相。与直接挤压工艺相比,采用先锻后挤大变形工艺后的组织均匀,化合物破碎严重,为进一步热处理和压力加工提供了良好的条件。先锻后挤工艺棒材最终抗拉强度和断后延伸率高于直接挤压棒材。屈服强度峰时效前先锻后挤的低于直接挤压的,而峰失效后前者高于后者。两种变形工艺棒材的分别于时效23和20 h达到强度峰值,先锻后挤工艺棒材的峰时效时抗拉强度、屈服强度、延伸率分别为453 MPa,390 MPa和12%。
The as-cast and as-cast microstructure of the as-cast 2D70 aluminum alloy semi-continuous ingot at different positions were observed by optical microscope (OM) and scanning electron microscopy (SEM). The microstructure of the as-cast solidified 2D70 aluminum alloy was observed by X-ray diffraction (XRD) ), Energy dispersive spectrometer (EDS) was used to analyze the formation phase of the alloy in the solidification process. The mechanical properties of the bars after different heat deformation and quenching aging treatments were tested. The results show that the solidified microstructure of 2D70 aluminum alloy is a typical dendritic structure. The ingot gradually tapers from the heart to the outside, and the equiaxial tendency increases gradually. The precipitation along the grain boundaries increases gradually. Typical as-cast microstructures are α (Al), gray honeycomb S (Al2CuMg), brown acicular Al7Cu2Fe, and brown bar or lamellar Al9FeNi phases. Compared with the direct extrusion process, using the first large deformation after extrusion process uniform organization, the compound broken serious, for further heat treatment and pressure processing provides a good condition. After the first forging process after the final tensile strength bar and elongation after breaking higher than the direct extrusion of bar. The yield strength of the peak before aging after squeezing less than direct squeeze, while the peak after the former is higher than the latter. The tensile strength, yield strength and elongation of the extruded bars reached 453 MPa, 390 MPa and 12% respectively after aging for 23 and 20 h, respectively.