发动机用TC17合金喷丸+微弧氧化涂层组织和疲劳性分析

通过实验研究了TC17钛合金的喷丸处理效果,利用微弧氧化方法来达到纳米晶过渡层组织结构重构的过程。通过实验测试的方式研究不同工艺涂层微观组织,硬度以及疲劳性能。研究结果表明:形成许多火山型微孔,孔洞尺寸也存在明显差异。对合金实施喷丸处理能够获得厚度更大微弧氧化层,引起了晶粒的明显细化,得到更加致密的组织结构。经过喷丸处理后,硬度为463HV0.1,表现为硬度提高。对不同深度区域的组织硬度进行对比发现,从表面过渡到基体中的范围内硬度呈现不断减小的变化趋势。当试样表面经喷丸处理后疲劳寿命可以达到15361周次,相对处理前的试样疲劳寿命延长了15%左右。对试样表面实施喷丸处理将会导致表面组织中产生众多疲劳源并进一步迁移到基体内,疲劳源范围也持续缩小,涂层表面存在众多微孔。

Surface Modification of TC17 Alloy by Shot-Peening and with Micro-Arc Oxidized Coating

The surfaces of TC17 Ti-alloy,an advanced aircraft engine blade material,were modified first by shot-peening and then by micro-arc oxidation(MAO).The microstructures and tribological behavior of the surface modified TC17 Ti-alloy were characterized with X-ray diffraction,scanning electron microscopy and conventional mechanical tools.The preliminary results show that the shot-peening significantly affected the compactness/thickness/density/porosity/hardness/corrosion-resistance/residual-stress of the MAO coatings because of the considerable reduction of grain-size,decrease of micro-voids and surface reconstruction.Specifically,the shot-peening greatly enhanced the hardness of TC17 alloy up to 463 HV0.1,with a top-down decreasing depth hardness profile,and increased the fatigue-life by 15% to 15,361 weeks.The growth of quite a few fatigue-sources into the substrate,induced by the shot peening,were observed.As expected,the MAO coating increased the corrosion resistance because MAO layer sealed the micro-pores of the alloy.