6063铝合金韧性断裂机制的研究

设计可实现不同应力状态的原位拉伸试样,在SEM下进行原位拉伸试验,对断裂过程做了详细的研究和分析.试验表明,不同应力状态下的试样表面在拉伸过程中都产生了大量的滑移带,但其韧性断裂机制不同.随着三轴应力度的降低,断裂从韧窝剪切机制向纯剪切断裂机制过渡,试件断口也由韧窝断裂模式向剪切断裂模式演变;6063铝合金的晶界最薄弱,微裂纹形核于晶界,随载荷增大,微裂纹之间通过扩展或剪切连接导致试样断裂;试样最小截面上的三轴应力度越小,试样断口的两个面上韧窝的取向越明显,而且断口越光滑.

Investigation of ductile fracture mechanism on 6063 aluminum alloy

In-situ tensile specimens were devised,which can product different stress states.Fracture process was investigated and analyzed carefully.Studies indicated that a lot of slip bands were produced in all specimens' surfaces under different stress states,but the ductile fracture mechanism was different.With stress triaxiality decreasing,the fracture modes were from dimple-shear fracture to pure shear fracture and the fracture surfaces were also from dimple fracture mode to shear fracture mode.The grain boundaries of 6063 aluminum alloy were the weakest area and microcracks initiated at the grain boundaries.With loading increasing,the specimens fractured due to the coalescence or shearing between the microcracks.The less the stress triaxiality,the more obvious the orientation of the dimple on the two surfaces of fracture surface and the smoother the fracture surfaces.