超声滚压对TC4表面组织和高频疲劳与超声疲劳性能的影响
发布时间：2018-11-15 20:54
【摘要】：钛及其合金具有高的比强度,优良的耐蚀性和生物相容性等优异性能,被广泛地应用于航空航天、生物医学和化学工业等领域。如今随着机械工业尤其是航空航天工业的不断发展,对钛合金的疲劳性能提出了更高的要求。因此,表面强化技术得以应用。本文通过整理多种表面机械强化技术,分析比较了各种技术对Ti-6A1-4V表面完整性和疲劳性能的影响。同时采用超声滚压技术对TC4进行了表面强化,并对其表面组织性能和高频-超声疲劳性能进行了系统的测试分析。研究的结论如下。(1)超声滚压技术可以在不破坏试样尺寸的基础上有效降低TC4的表面粗糙度,提高表层硬度,细化表层晶粒,并在TC4表层引入了一层残余压应力。(2)在高频疲劳试验和超声疲劳试验中,TC4超声滚压试样的疲劳寿命都降低了。原因是由于超声滚压使TC4表层晶粒细化,表面强度提高,导致材料不均匀,从而在循环加载过程中发热量更大,影响了疲劳寿命。(3)对TC4超声滚压试样进行真空热处理后,表层形成更均匀的梯度结构,经过200 ℃和300 °C处理后试样的疲劳寿命比热处理前稍有提高;但是当温度提高到400 ℃及以上时,试样的疲劳寿命大幅度降低。(4)相同应力幅下,与超声疲劳加载相比,试样表面的残余压应力在高频疲劳加载过程中释放的更快,最终残留的压应力更小。
[Abstract]:Titanium and its alloys have been widely used in aerospace, biomedical and chemical industries because of their high specific strength, excellent corrosion resistance and biocompatibility. With the development of machinery industry, especially aerospace industry, the fatigue properties of titanium alloys are required. Therefore, surface strengthening technology has been applied. In this paper, the effects of various surface mechanical strengthening techniques on the surface integrity and fatigue properties of Ti-6A1-4V are analyzed and compared. At the same time, ultrasonic rolling technique was used to strengthen the surface of TC4, and the surface microstructure and high-frequency ultrasonic fatigue properties were tested and analyzed systematically. The conclusions are as follows: (1) Ultrasonic rolling technology can effectively reduce the surface roughness of TC4 without destroying the sample size, improve the surface hardness and refine the surface grain. A layer of residual compressive stress was introduced into the surface of TC4. (2) in high frequency fatigue test and ultrasonic fatigue test, the fatigue life of TC4 ultrasonic rolling specimen was decreased. The reason is that the surface grain of TC4 is refined by ultrasonic rolling, and the surface strength is increased, which leads to the uneven material, which results in more heat in the process of cyclic loading, which affects the fatigue life. (3) after the vacuum heat treatment of the TC4 ultrasonic rolling specimen, A more uniform gradient structure was formed in the surface layer, and the fatigue life of the specimen treated at 200 鈩，
本文编号：2334430
[Abstract]:Titanium and its alloys have been widely used in aerospace, biomedical and chemical industries because of their high specific strength, excellent corrosion resistance and biocompatibility. With the development of machinery industry, especially aerospace industry, the fatigue properties of titanium alloys are required. Therefore, surface strengthening technology has been applied. In this paper, the effects of various surface mechanical strengthening techniques on the surface integrity and fatigue properties of Ti-6A1-4V are analyzed and compared. At the same time, ultrasonic rolling technique was used to strengthen the surface of TC4, and the surface microstructure and high-frequency ultrasonic fatigue properties were tested and analyzed systematically. The conclusions are as follows: (1) Ultrasonic rolling technology can effectively reduce the surface roughness of TC4 without destroying the sample size, improve the surface hardness and refine the surface grain. A layer of residual compressive stress was introduced into the surface of TC4. (2) in high frequency fatigue test and ultrasonic fatigue test, the fatigue life of TC4 ultrasonic rolling specimen was decreased. The reason is that the surface grain of TC4 is refined by ultrasonic rolling, and the surface strength is increased, which leads to the uneven material, which results in more heat in the process of cyclic loading, which affects the fatigue life. (3) after the vacuum heat treatment of the TC4 ultrasonic rolling specimen, A more uniform gradient structure was formed in the surface layer, and the fatigue life of the specimen treated at 200 鈩，
本文编号：2334430
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