激光喷丸强化镍基高温合金Inconel X-750抗热腐蚀性能研究

发布时间：2018-04-17 18:50

  本文选题：激光喷丸 + 镍基高温合金　； 参考：《江苏大学》2017年硕士论文

【摘要】：激光喷丸(Laser Peening,LP)是一种新型的表面强化技术,它通过作用在金属材料表面的高压冲击波,使材料发生塑性变形,从而形成高幅值的残余压应力,并诱导材料表层的位错增殖和晶粒细化,最终提高材料的表面性能。研究LP工艺对镍基高温合金抗热腐蚀性能的影响对于拓展LP工艺在腐蚀领域的应用具有十分重要的意义。本文开展了激光喷丸强化Inconel X-750镍基高温合金抗热腐蚀性能研究,探讨了激光喷丸强化抗热腐蚀性能的内在机理。主要工作有以下几点:(1)介绍了激光喷丸表面改性技术的基本原理和技术特点,分析了激光喷丸对金属材料的表面形貌、显微硬度、残余应力及微观组织的影响机理;特别是对激光喷丸诱导的晶粒细化和位错增殖机制进行了详细的分析,并基于热腐蚀的基本理论,研究了激光喷丸改善镍基高温合金抗热腐蚀性能的本质原因。(2)开展了Inconel X-750镍基高温合金在不同激光脉冲能量下和不同喷丸次数下的激光喷丸实验,通过扫描显微镜、显微硬度计和X射线应力仪测试了激光喷丸材料表面三维形貌、粗糙度、显微硬度、残余应力和微观组织。结果表明,在最佳激光脉冲能量范围内,随着激光脉冲能量的增加,合金表面的显微硬度、表面粗糙度和残余应力均增大,且表层晶粒发生细化;在1次激光喷丸的基础上进行第2次喷丸后,材料表面的显微硬度和残余应力进一步增大,且晶粒细化程度加剧,而材料表面粗糙度有所降低。(3)对LP试样和未处理试样进行了950℃(75%Na2SO4+25%Na Cl)混合盐膜中的热腐蚀实验,测定了试样的腐蚀动力学曲线,表明LP试样的腐蚀失重和腐蚀深度明显低于未处理试样,腐蚀表面出现一层致密稳定的保护性Cr2O3氧化膜。同时对腐蚀表面形貌和截面形貌进行SEM和EDS分析,通过观察得出LP后合金的晶粒细化和残余压应力有效阻止了O2、S等的侵蚀,从而提高了材料的抗热腐蚀性能。
[Abstract]:Laser peening (LPN) is a new type of surface strengthening technique, which causes plastic deformation of metal material by high pressure shock wave acting on the surface of metal material, thus forming high amplitude residual compressive stress.The dislocation proliferation and grain refinement of the surface layer were induced to improve the surface properties of the materials.It is very important to study the effect of LP process on the thermal corrosion resistance of nickel-based superalloy in order to expand the application of LP process in corrosion field.In this paper, the thermal corrosion resistance of Inconel X-750 nickel-base superalloy strengthened by laser shot peening is studied, and the internal mechanism of laser shot peening strengthening thermal corrosion resistance is discussed.The basic principle and technical characteristics of laser shot peening surface modification technology are introduced. The influence mechanism of laser shot peening on the surface morphology, microhardness, residual stress and microstructure of metal materials is analyzed.In particular, the mechanism of grain refinement and dislocation proliferation induced by laser shot peening is analyzed in detail, and based on the basic theory of hot corrosion,The essential cause of improving the thermal corrosion resistance of nickel-based superalloy by laser shot peening was studied. (2) the laser shot peening experiments of Inconel X-750 nickel base superalloy under different laser pulse energy and different shot peening times were carried out.The surface morphology, roughness, microhardness, residual stress and microstructure of laser shot peening materials were measured by microhardness tester and X-ray stress meter.The results show that the microhardness, surface roughness and residual stress of the alloy increase with the increase of laser pulse energy in the optimal laser pulse energy range, and the grain size of the surface layer is refined.After the second shot peening on the basis of one laser shot peening, the microhardness and residual stress on the surface of the material are further increased, and the grain refinement degree is aggravated.On the other hand, the surface roughness of LP and untreated samples were tested by hot corrosion experiments in Na _ 2SO _ 4 25%Na _ 1 mixed salt film at 950 鈩，

本文编号：1764832