7050高强铝合金铆钉丝材T73双级时效工艺

针对国产7050高强铝合金铆钉丝材，采用室温拉伸、室温剪切、镦粗试验的方法，研究了经177～182℃不同二级时效时间后7050铝合金丝材的性能。利用扫描电镜(SEM)、透射电镜(TEM)观察合金不同时效工艺下断口组织和析出相形貌特征。结果表明，拉伸强度和剪切强度随二级时效温度的升高、二级时效时间的延长逐渐降低，剪切强度低于330 MPa时镦粗试样不开裂。TEM微观组织显示，随二级时效温度的升高、时间的延长析出相形貌变化不大，但析出相的尺寸随时效温度的升高逐渐长大、间距逐渐增大；拉伸断口形貌显示，二级时效的断裂方式均为韧窝断裂和沿晶断裂的混合断裂模式，随二级时效温度的升高和保温时间的延长，断口中韧窝数量逐渐增加且尺寸变大，沿晶断裂逐渐减少。

T73 two-stage aging process of 7050 high-strength aluminum alloy rivet wire

Properties of the domestic 7050 high strength aluminum alloy wire secondary aged at 177-182 ℃ for different time were studied by room temperature tensile, room temperature shearing and upsetting tests. The fracture morphology was studied by means of scanning electron microscope (SEM) and the precipitation phase was studied by means of transmission electron microscope (TEM). The results show that the tensile strength and the shearing strength decrease gradually with the increase of secondary aging temperature and secondary aging time. The upsetting specimens do not crack when the shear strength is less than 330 MPa. The TEM microstructure show that the higher the aging temperature and the long the aging time, the larger the size and the inter-spacing of precipitated phase are, but morphology of precipitated phase changes little. The tensile fracture morphologies show that the fracture mode is a mixture of ductile fracture and intergranular fracture. The dimple number and size increase and the intergranular fracture decreases with the increase of secondary aging temperature and aging time.