| METALS AND METAL MATRIX COMPOSITES |
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| Microscopic Mechanism of Fatigue Crack Propagation in TC4-DT Titanium Alloy |
| GUO Ping, ZHAO Yongqing, HONG Quan, MAO Xiaonan, HOU Hongmiao, PAN Hao
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| Northwest Institute for Nonferrous Metal Research, Xi’an 710016 |
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Abstract The microscopic mechanism of crack propagation in TC4-DT titanium alloy was discussed by fracture analysis. Specifically speaking, the analysis of microscopic mechanism of crack propagation corresponding to the TC4-DT titanium alloy with diverse microstructures was conducted from the formation of microcracks, fatigue crack propagation of initial stage, near-threshold zone and the steady-state zone. The analysis results indicated that the cyclic loading caused the rough fracture surface and the dislocation accumulation at the phase interface during plastic deformation to induce crack initiation for the lamellar structure. The cracks in the equiaxed microstructure were primarily derived from the fracture surface generated by small grain deformation process. In the near-threshold area, the dislocations accumulation during the deformation of the equiaxed grains gave rise to the cracks along the grain boundary, accelerating the crack propagation. The size effect of the secondary α phase in double-layer structure also sped up the crack propagation. In the steady-state extension zone, the fracture surface transitions from the zigzag fracture mode of the first stage to the striation fracture mode of the second stage, presenting the plastic strip fracture mechanism.
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Published: 29 August 2019
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| About author:: Ping Guo,received her Ph.D. degree in materials from Northwestern Polytechnical University. She is currently a professor in Titanium Alloy Research Center in Northwest Institute for Nonferrous Metal Research and parti-cipates in the research of titanium alloy. She has published more than 20 articles, and applied for the patent more than 20. |
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2019, Vol. 33 
