7056铝合金厚板的组织和性能

Microstructure and Mechanical Properties of 7056 Aluminum Alloy Thick Plates

通过金相显微镜、透射电镜、扫描电镜观察及X射线衍射织构测量与拉伸试验,研究了40mm厚7056铝合金厚板热轧态与时效后不同厚度层的微观组织与力学性能。结果表明,热轧态厚板不同厚度层的组织有很大差别;表层第二相弥散,尺寸相对较小;中心层有粗大的第二相,分布集中。从表层到中心层,剪切织构减少,中心层变形织构最多,不同厚度层立方织构差别不大。固溶后表层再结晶织构增加,剪切织构减少,中心层变形织构增强。固溶时效后表层与中心层晶内均出现大量均匀细小的η′相,晶界处都出现不连续析出相与一定宽度的无沉淀析出带。40mm厚板(7056铝合金)最优固溶制度是470℃/3 h,时效后表层屈服强度为605 MPa,抗拉强度达628 MPa;T/4层屈服强度626 MPa,抗拉强度达643 MPa;中心层屈服强度623 MPa,抗拉强度达639 MPa。

Tensile tests, optical microscopy（OM）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and transmission electron microscopy（TEM） were used to characterize the mechanical properties and microstructure of 7056 aluminum alloy plates, which were rolled to a thickness of 40 mm. The results show that the microstructure of 7056 hot rolled plate is inhomogeneous in different layers. The second phase particles on the surface are distributed dispersively and their size is relatively small, while when they are concentrated at the center, the size is relatively large. From the surface to the center, the shear texture is gradually reduced. The content of the deformed texture in the center layer is the largest, and the difference between the cube textures in each layer is not significant. After solution treatment, the recrystallization texture increases and the shear texture decreases on the surface, and the deformed texture of the central layer increases. After aging, a large amount of homogeneous and fine η＇ phases appear in the surface layer and the center layer, while discontinuous precipitates and a certain width of precipitation-free zone can be observed at the grain boundaries. The optimal solution treatment of 40 mm thick 7056 plate is 470 °C for 3 h. After aging, the yield strength and the tensile strength of the surface layer are 605 MPa and 628 MPa, respectively, those of T/4 layer are 626 MPa and 643 MPa, respectively, and those of the center layer are 623 MPa and 639 MPa, respectively.