6063铝合金航空铆钉等径角挤压-冷镦复合成形实验研究

Experimental study on equal channel angular pressing and cold upsetting composite forming for 6063 aluminum alloy aviation rivets

为了探究等径角挤压-冷镦复合成形的铝合金航空铆钉的力学性能及失效形式,对6063铝合金航空铆钉进行了等径角挤压-冷镦复合成形实验及不同类型的失效实验,并通过SEM观察成形铆钉的断口形貌。结果表明:相对单一冷镦成形铆钉,纯拉伸时,复合成形铆钉承受的最大拉伸载荷提升了约14.2%,失效形式均为头部拉脱失效,微观断口的孔洞数目明显减少且韧窝变浅;纯剪切时,复合成形铆钉承受的最大剪切载荷提升了约15.2%,失效形式均为沿剪切方向的杆部剪断失效,且断口表面的剪切韧窝变大、变浅;复合加载时,复合成形铆钉承受的最大载荷提升了约45.6%,失效形式均为杆部以一定角度弯曲的剪切断裂失效,且断口表面存在更多的剪切韧窝。

In order to explore the mechanical properties and failure forms of aluminum alloy aviation rivets formed by equal channel angular pressing(ECAP)and cold upsetting(CU)composite forming,for 6063 aluminum alloy aviation rivets,the ECAP-CU composite forming experiments and different types of failure experiments were carried out,and the fracture morphology of formed rivets was observed by SEM.The results show that compared with the rivet formed by single cold upsetting,the maximum tensile load of the rivet by the composite forming is increased by about 14.2%in pure tension,the failure form is pull-off failure of head,the number of holes in the micro-fracture is significantly reduced,and the dimples become shallow.However,in pure shear,the maximum shear load of the rivet by the composite forming is increased by about 15.2%,the failure form is the shear failure of rod along the shearing direction,and the shear dimples on the fracture surface become larger and shallower.When composite loading,the maximum load of the rivet by the composite forming is increased by about 45.6%,the failure form is shear fracture in which the rod is bent with a certain angle,and more shear dimples appear on the fracture surface.