激光冲击强化TC11钛合金高温摩擦磨损性能研究

发布时间：2018-01-07 03:11

本文关键词：激光冲击强化TC11钛合金高温摩擦磨损性能研究　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：激光冲击强化(laser shock peening,LSP)利用诱导产生的高压、瞬时等离子体冲击波实现对材料改性,可以有效提高材料的耐磨性。本文研究了TC11钛合金在不同激光冲击工艺参数以及不同环境下的磨损行为和磨损性能变化。采用SEM、EDS等对磨痕表面和截面的形貌、成分和结构等进行了分析,探讨了TC11钛合金激光冲击前后的主要磨损形式,分析了激光冲击强化提升TC11高温下耐磨性的机制,为开展高温环境下钛合金摩擦磨损性能的研究奠定了理论基础。论文的主要研究内容和结论如下:(1)激光冲击工艺参数对TC11钛合金摩擦性能有较大影响,随着激光冲击层数的增加摩擦系数达到稳定的时间越短,光斑搭接率为50%时摩擦系数较大。激光冲击试样的摩擦系数随着温度的升高逐渐减小并且波动性较小。激光冲击前后试样的摩擦系数均随着载荷的增加呈现逐渐增加的趋势。(2)激光冲击强化技术可以显著提高TC11钛合金的耐磨性能。钛合金高温环境下的耐磨性随着激光冲击层数的增加而逐渐提高。600°C及以下,TC11钛合金经过激光冲击后,其耐磨性随着温度的升高而增强,而未冲击试样的耐磨性随着温度升高先升高后下降。25N及以下,激光冲击前后钛合金的磨损率均随着载荷的增大而增大,然而经激光冲击后试样的磨损率较小。(3)未冲击试样的磨痕表面出现许多裂纹,磨屑呈现大块剥落,其主要磨损机制为剥层磨损、磨粒磨损和氧化磨损。经过激光冲击强化处理的TC11钛合金,在高温条件下的主要磨损机制为磨粒磨损和氧化磨损,并且随着温度升高氧化磨损程度越严重,氧化磨损引起的材料损失远低于剥层磨损。(4)TC11钛合金激光冲击后耐磨性提高的主要机制可归纳为:a、钛合金激光冲击强化后,材料的显微结构和硬度沿深度方向上呈现梯度分布,各层间具有较好的结合性,表面硬度较高;b、钛合金经过激光冲击后表层被压实,摩擦过程中形成的机械混合层比较致密;c、激光冲击强化后的钛合金表面残留较大的残余压应力,有效减少因裂纹萌生和扩展引起的剥层磨损。
[Abstract]:Laser shock peeningine (LSPs) was modified by high pressure and transient plasma shock wave induced by laser shock. In this paper, the wear behavior and wear properties of TC11 titanium alloy under different laser impact parameters and in different environments were studied. SEM was used to improve the wear resistance of the alloy. The morphology, composition and structure of wear mark surface and section were analyzed by EDS, and the main wear patterns of TC11 titanium alloy before and after laser impact were discussed. The mechanism of enhancing wear resistance of TC11 at high temperature by laser shock strengthening was analyzed. It lays a theoretical foundation for the study of friction and wear properties of titanium alloys under high temperature. The main contents and conclusions of this paper are as follows: 1). Laser impact process parameters have great influence on the friction properties of TC11 titanium alloy. With the increase of the number of laser shock layers, the time of the friction coefficient reaching stability is shorter. The friction coefficient of laser impact specimen decreases gradually with the increase of temperature and the fluctuation is small. The friction coefficient of the sample before and after laser shock increases with the increase of load. A gradual increasing trend. 2) the wear resistance of TC11 titanium alloy can be significantly improved by laser impact strengthening technology. The wear resistance of titanium alloy increases gradually with the increase of laser impact layer number. 600 掳C and below. The wear resistance of TC11 titanium alloy increases with the increase of temperature, while the wear resistance of unimpacted titanium alloy increases first with the increase of temperature and then decreases under .25N. The wear rate of titanium alloy increases with the increase of load before and after laser impact. However, after laser impact, the wear rate of titanium alloy is smaller. 3) there are many cracks on the surface of wear mark of unimpacted specimen. The main wear mechanisms were delamination, abrasive wear and oxidation wear. The TC11 titanium alloy was strengthened by laser impact. The main wear mechanisms at high temperature are abrasive wear and oxidation wear, and the degree of oxidation wear becomes more serious with the increase of temperature. The material loss caused by oxidation wear is much lower than that of delamination wear. TC11 titanium alloy after laser impact. The main mechanism of improving wear resistance can be summarized as: 1: a, after laser shock hardening of titanium alloy. The microstructure and hardness of the material show gradient distribution along the depth direction. The surface layer of b-, titanium alloy is compacted after laser impact, and the mechanical mixing layer formed in the process of friction is compact. The large residual compressive stress on the surface of titanium alloy strengthened by laser shock can effectively reduce the delamination and wear caused by crack initiation and propagation.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.23;TG665

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