7050-T7452高强铝合金的开坯与锻造工艺研究

Cogging and Forging Techniques for 7050-T7452 High-strength Aluminum Alloy

为了研究7050高强铝合金开坯工艺的变形均匀性及锻件的断裂韧性,采用数值模拟、微观组织分析及紧凑拉伸试样的KIC试验等,分析研究7050高强铝合金铸坯改锻和挤压坯锻造的变形均匀性、显微组织和断裂韧性,得到了两种开坯工艺条件下坯料的平均等效应变、变形均匀系数、晶粒尺寸大小及分布和断裂韧度值。结果表明:铸坯改锻工艺的变形均匀性较好,其平均等效应变约为7.2,变形均匀系数约为0.475;挤压坯锻造工艺的变形均匀性较差,其平均等效应变约为1.9,变形均匀系数约为0.954;铸坯改锻工艺的平均晶粒尺寸与挤压坯锻造工艺基本相当,约为7.5μm,但铸坯改锻工艺的晶粒尺寸比挤压坯锻造更均匀;铸坯改锻工艺下锻件的KIC满足AMS4108F标准要求,而挤压坯锻造工艺不满足,其原因是挤压坯锻造后脆性较大,并残留有挤压织构。

The numerical simulation,microstructure analysis and KIC testing of compact-tension specimen have been employed to explore the deformation uniformity,microstructure and fracture toughness of techniques in forging process for 7050 high strength aluminum alloy ingot and extruded stock.The mean value of equivalent strain,deformation uniformity coefficient,and dimension distribution of grains have been achieved as well as magnitude of fracture toughness in condition of the former two different techniques respectively.The results indicate that the technique which uses ingot blank for forging has better deformation uniformity,and the mean value of its equivalent strain is approximate 7.2 while the deformation uniformity coefficient is approximate 0.475.However,the deformation uniformity of technique which uses extruded stock for forging is worse,and the mean value of its equivalent strain is approximate 1.9 while deformation uniformity coefficient is approximate 0.954.The two different techniques have an equivalent grain size and the value is approximate 7.5μm,but the grain size of the former technique is more homogeneous than the latter.The KIC of technique which uses ingot stock to forge meets requirements of AMS4108F standard,but it is not right for the latter technique because of greater brittleness with remaining extruded texture in extruded stock after forging.