Li Fagui, Chen Xiyu, Wang Yuannan, Zhao Guolong, Yang Yinfei
College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics & Astronautics, Nanjing 210016, China.
Nanjing High Speed & Accurate Gear (Group) Co., Ltd., Nanjing 211100, China.
Materials (Basel). 2023 Aug 20;16(16):5702. doi: 10.3390/ma16165702.
The creep stress exponent is commonly employed to characterize the deformation mechanism during the steady-state creep stage, serving as an indicator of creep behavior. The creep phenomenon of high melting point metallic materials is not obvious at room temperature. However, the nanoindentation method proves suitable for investigating the creep properties of metallic materials under such conditions. Consequently, this paper places emphasis on measuring the creep stress exponent of TC17 titanium alloy at room temperature using the load preservation stage of the nanoindentation method with a constant loading rate. In order to investigate the effects of loading rate and maximum load on the experimental results, different loading rates were applied to the diamond Berkovich indenter to reach different maximum loads. The indenter was held under the maximum load for a duration of 360 s, and the relationship between the indentation strain rate and indentation stress during the holding process was used to obtain the creep stress exponent of the material at room temperature. The findings indicate that within the loading rate range of 1.25 to 15 mN/s and maximum load range of 50 to 300 mN, the influence on the experimental results is insignificant. Ultimately, the distribution range of the creep stress exponent for TC17 titanium alloy at room temperature was measured to be 8.524-8.687.
蠕变应力指数通常用于表征稳态蠕变阶段的变形机制，作为蠕变行为的一个指标。高熔点金属材料在室温下的蠕变现象并不明显。然而，纳米压痕法被证明适用于研究此类条件下金属材料的蠕变性能。因此，本文重点利用纳米压痕法的恒加载速率保载阶段来测量TC17钛合金在室温下的蠕变应力指数。为了研究加载速率和最大载荷对实验结果的影响，对金刚石Berkovich压头施加不同的加载速率以达到不同的最大载荷。压头在最大载荷下保持360 s，利用保持过程中压痕应变速率与压痕应力之间的关系来获得材料在室温下的蠕变应力指数。结果表明，在1.25至15 mN/s的加载速率范围和50至300 mN的最大载荷范围内，对实验结果的影响不显著。最终，测得TC17钛合金在室温下蠕变应力指数的分布范围为8.524 - 8.687。
