本文選題：激光噴丸 + 鎳基高溫合金　； 參考：《江蘇大學(xué)》2017年碩士論文

【摘要】：激光噴丸(Laser Peening,LP)是一種新型的表面強(qiáng)化技術(shù),它通過(guò)作用在金屬材料表面的高壓沖擊波,使材料發(fā)生塑性變形,從而形成高幅值的殘余壓應(yīng)力,并誘導(dǎo)材料表層的位錯(cuò)增殖和晶粒細(xì)化,最終提高材料的表面性能。研究LP工藝對(duì)鎳基高溫合金抗熱腐蝕性能的影響對(duì)于拓展LP工藝在腐蝕領(lǐng)域的應(yīng)用具有十分重要的意義。本文開(kāi)展了激光噴丸強(qiáng)化Inconel X-750鎳基高溫合金抗熱腐蝕性能研究,探討了激光噴丸強(qiáng)化抗熱腐蝕性能的內(nèi)在機(jī)理。主要工作有以下幾點(diǎn):(1)介紹了激光噴丸表面改性技術(shù)的基本原理和技術(shù)特點(diǎn),分析了激光噴丸對(duì)金屬材料的表面形貌、顯微硬度、殘余應(yīng)力及微觀組織的影響機(jī)理;特別是對(duì)激光噴丸誘導(dǎo)的晶粒細(xì)化和位錯(cuò)增殖機(jī)制進(jìn)行了詳細(xì)的分析,并基于熱腐蝕的基本理論,研究了激光噴丸改善鎳基高溫合金抗熱腐蝕性能的本質(zhì)原因。(2)開(kāi)展了Inconel X-750鎳基高溫合金在不同激光脈沖能量下和不同噴丸次數(shù)下的激光噴丸實(shí)驗(yàn),通過(guò)掃描顯微鏡、顯微硬度計(jì)和X射線應(yīng)力儀測(cè)試了激光噴丸材料表面三維形貌、粗糙度、顯微硬度、殘余應(yīng)力和微觀組織。結(jié)果表明,在最佳激光脈沖能量范圍內(nèi),隨著激光脈沖能量的增加,合金表面的顯微硬度、表面粗糙度和殘余應(yīng)力均增大,且表層晶粒發(fā)生細(xì)化;在1次激光噴丸的基礎(chǔ)上進(jìn)行第2次噴丸后,材料表面的顯微硬度和殘余應(yīng)力進(jìn)一步增大,且晶粒細(xì)化程度加劇,而材料表面粗糙度有所降低。(3)對(duì)LP試樣和未處理試樣進(jìn)行了950℃(75%Na2SO4+25%Na Cl)混合鹽膜中的熱腐蝕實(shí)驗(yàn),測(cè)定了試樣的腐蝕動(dòng)力學(xué)曲線,表明LP試樣的腐蝕失重和腐蝕深度明顯低于未處理試樣,腐蝕表面出現(xiàn)一層致密穩(wěn)定的保護(hù)性Cr2O3氧化膜。同時(shí)對(duì)腐蝕表面形貌和截面形貌進(jìn)行SEM和EDS分析,通過(guò)觀察得出LP后合金的晶粒細(xì)化和殘余壓應(yīng)力有效阻止了O2、S等的侵蝕,從而提高了材料的抗熱腐蝕性能。
[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，

本文編號(hào)：1764832