Nanocrystallization and enhanced surface mechanical properties of commercial pure titanium by electropulsing-assisted ultrasonic surface rolling
Nanocrystallization and enhanced surface mechanical properties of commercial pure titanium by electropulsing-assisted ultrasonic surface rolling
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DOI：
10.1016/j.matdes.2018.04.027
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发表时间：
2018-07-05
影响因子：
8.4
通讯作者：
Tang, Guoyi
中科院分区：
文献类型：
--
作者：
Ye, Yongda;Kure-Chu, Song-Zhu;Tang, Guoyi
在这项研究中，梯度纳米晶化和增强的表面机械性能，在商业纯钛，这是诱导的电脉冲辅助超声表面轧制工艺（EP-USRP），进行了系统的研究。结果表明，在500 Hz的最佳频率的EP-USRP是优于传统的超声表面滚压工艺（USRP）在实现优异的表面机械性能，包括较低的摩擦系数和较少的磨损量（最大磨痕深度减少到三分之二的USRP）。这种增强可能归因于更高的表面最大硬度（308 HV，与车削样品相比增加了46.7%）、更深的严重塑性变形层（480 μ m，类似于USRP的0.5倍）、更小的表面粗糙度（Ra 0.026 μ m）和更高的压缩残余应力。在电脉冲诱发塑性和超声冲击诱发加工硬化之间存在平衡。在最佳条件下，由于电脉冲的热和非热效应以及USRP的超声振动能量，不动位错的流动性显着提高，导致更高的应变和位错密度;这些诱导亚晶中的进一步动态再结晶，直到达到新的平衡。(C)2018爱思唯尔有限公司版权所有
In this study, gradient nanocrystallization and enhanced surface mechanical properties in commercial pure titanium, which were induced by an electropulsing-assisted ultrasonic surface rolling process (EP-USRP), were systematically investigated. The results indicated that EP-USRP at an optimum frequency of 500 Hz is advantageous over a conventional ultrasonic surface rolling process (USRP) in achieving excellent surface mechanical properties, including a lower friction coefficient and less wear loss (maximum depth of wear scar decreased to two-thirds of that of USRP). Such enhancements may be attributed to a higher surface maximum hardness (308 HV ,increased by 46.7% compared to the turning sample), deeper severe plastic deformation layer (480 mu m, similar to 0.5 times greater than that of USRP), smaller surface roughness (Ra 0.026 mu m), and higher compressive residual stresses. There is a balance between electropulsing-induced ductility and ultrasonic impact-induced work hardening. At the optimum conditions, the mobility of immobile dislocations is remarkably improved owing to the thermal and athermal effects of electropulsing as well as the ultrasonic vibration energy from USRP, leading to higher strains and dislocation densities; these induce further dynamic recrystallization in the sub-grains until a new balance is reached. (C) 2018 Elsevier Ltd. All rights reserved.