Residual stress and fracture strength of brazed joint of ceramic and titanium alloy with the aid of laser deposited functionally graded material layers
Residual stress and fracture strength of brazed joint of ceramic and titanium alloy with the aid of laser deposited functionally graded material layers
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DOI：
10.1016/j.jmapro.2018.06.041
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发表时间：
2018-08
影响因子：
6.2
通讯作者：
J. M. Shi;J. M. Shi;N. Ma;L. X. Zhang;J. Feng
中科院分区：
文献类型：
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作者：
J. M. Shi;J. M. Shi;N. Ma;L. X. Zhang;J. Feng
为了提高陶瓷(ZRC-SiC)与钛合金(TC4)钎焊接头的强度，设计了激光沉积功能梯度材料层(FGM层)以降低钎焊接头中的残余应力。建立了焊接接头的仿真模型，研究了功能梯度材料层降低残余应力的机理。结果表明，钎焊界面法向的残余应力分量(法向应力)在钎缝边缘为拉伸应力，而在靠近钎焊缝的钎焊界面上的面内残余应力分量为压缩应力。功能梯度材料层的采用显著降低了法向残余应力和面内残余应力。在剪切试验过程中，法向应力集中在靠近焊缝处的ZRC-SIC边缘。将剪切实验中测得的645 N和1365 N分别施加于ZrC-SiC/TC4接头模型和ZrC-SiC/TC4-FGM接头模型中，两种模型的局部法向断裂应力分别为648 Mpa和671 Mpa。虽然由于钎焊产生的残余应力不同，两种模型的断裂力有很大的不同，但识别出的局部断裂应力接近。预测的裂纹起始位置在靠近钎焊区的ZRC-SIC拐角附近，这与实验中观察到的情况一致。
To improve the strength of a ceramic (ZrC-SiC) and a titanium alloy (TC4) brazed joint, laser deposited functionally graded material layers (FGM layers) between ZrC-SiC and TC4 were designed to reduce the residual stress in the brazed joint. A simulation model of the brazed joint was created to investigate the mechanism of residual stress reduction due to FGM layers. The results show that the residual stress component in the normal direction of the brazing interface (normal stress) is tensile at the ZrC-SiC edges and the in-plane residual stress component on the brazing interface is compressive in the ZrC-SiC adjacent to the brazing seam. The adoption of the FGM layers significantly reduces both the normal residual stress and in-plane residual stress. During the shear test, the normal stress concentrates at the ZrC-SiC edges near the brazing seam. By applying fracture forces 645 N and 1365 N measured in shear experiments to the ZrC-SiC/TC4 joint model and ZrC-SiC/TC4-FGM joint model respectively, the local fracture stress in the normal direction is identified to be 648 MPa and 671 MPa from both models, respectively. Although the fracture force for both models are quite different due to the difference of residual stress produced by brazing, the identified local fracture stress is close each other. The predicted cracking initial position is around the corner of the ZrC-SiC close to the brazed zone which is the same as observed in experiments.