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对TA15合金在SANS CMT4104型高温电子拉伸实验机上进行恒应变速率超塑性拉伸试验,研究了合金超塑性变形过程中空洞演化及断裂行为。结果表明:超塑性变形过程中,TA15合金空洞含量和大小受变形量、应变速率和应变速率敏感性指数m值的影响较大。随变形量增大,空洞分别沿拉伸轴方向和垂直于拉伸轴方向发生了聚合和连接,空洞长大由形核时的一般扩散机制向塑性变形机制转变。TA15合金超塑性拉伸试样断口呈针点状,断口上含有大量的韧窝状空洞,空位聚集-空洞连接是TA15合金超塑性断裂的主要机制。
The constant strain rate superplastic tensile test was carried out on the TA15 alloy on the SANS CMT4104 high temperature electronic tensile testing machine to study the cavitation evolution and fracture behavior in the superplastic deformation process. The results show that in the process of superplastic deformation, the void content and size of TA15 alloy are greatly affected by the deformation, strain rate and strain rate sensitivity index m. With the increase of deformation, the voids are polymerized and connected along the direction of the stretching axis and perpendicular to the direction of the stretching axis, respectively. The cavity growth changes from the general diffusion mechanism during nucleation to the plastic deformation mechanism. The fracture of TA15 alloy superplasticity tensile specimen is needle-like, the fracture contains a large number of dimple-like cavities. The vacancy accumulation-void connection is the main mechanism of TA15 alloy superplastic fracture.