TA15钛合金薄板室温弯曲有限元模拟及破裂机制

Finite element simulation and fracture mechanism of TA15 titanium alloy sheet bending at room temperature

以TA15钛合金薄板为研究对象,利用Abaqus软件模拟了室温下TA15板材在不同弯曲角度下的变形过程,得到了不同弯曲角度下的应力-应变分布情况,确定了TA15钛合金薄板弯曲变形破裂的极限角度。为验证数值模拟结果和研究破裂机制,利用弯曲试验机进行了三点弯曲试验。结果表明,当弯曲角度达到120°时,试样发生破裂,试样产生裂纹的角度与有限元模拟结果一致,弯曲处剖面的硬度值与模拟结果的应力值趋势同样吻合。此外,通过观察试样不同弯曲角度的剖面显微组织,得到TA15板材冷弯破坏机制。结果表明,在不同的弯曲角度下,变形区域均出现细小晶粒,破裂机制为:在弯曲角度较小时,组织以纤维状为主,有少量等轴α相和晶间β相;随着弯曲角度增加,有亚晶界在变形区域产生,并且拉长的条状α相部分破碎,有更加细小条状和微小等轴α相出现,当弯曲角度进一步增大时,基体中的条状α相部分破碎,空洞的萌生导致破裂。

Taking TA15 titanium alloy sheet as the research object,the Abaqus software was used to simulate the deformation process of TA15 sheet with different bending angles at room temperature.The stress-strain distribution with different bending angles was obtained,and the ultimate fracture angle in bending deformation of TA15 titanium alloy sheet was determined.To verify the numerical simulation results and study the fracture mechanism,the three-point bending tests were carried out by bending tester.The results show that when the bending angle reaches 120°,the specimen breaks,and the angle of fracture formation of the specimen is consistent with the finite element simulation results,and the hardness value of the bending section is also consistent with the stress value trend of the simulation results.In addition,the cold bending failure mechanism of TA15 sheet was obtained by observing the cross-section microstructure of the specimen with different bending angles.The results show that with different bending angles,the fine grains appear in the deformation areas,and the fracture mechanism is that when the bending angle is small,the structure is mainly fibrous,with a small amount of equiaxedαphase and intergranularβphase.As the bending angle increases,the sub-grain boundaries are generated,and the elongated stripαphase partially breaks,and the finer strip and tiny equiaxedαphase appears.When the bending angle further increases,the stripαphase in the matrix partially breaks,and the initiation of voids leads to fracture.