【摘要】：在現(xiàn)如今的工業(yè)生產(chǎn)實(shí)踐中,許多關(guān)鍵位置的零部件受限于其復(fù)雜的腐蝕性服役環(huán)境,并同時(shí)受到循環(huán)交變載荷的交互作用,這些零部件往往會(huì)產(chǎn)生腐蝕疲勞斷裂而導(dǎo)致破壞性的事故。現(xiàn)代機(jī)械構(gòu)件再制造工程核心科學(xué)問(wèn)題之一就是如何選用先進(jìn)的表面處理技術(shù)來(lái)強(qiáng)化關(guān)鍵零部件,延長(zhǎng)服役壽命的同時(shí)提高其使用的可靠性。激光沖擊強(qiáng)化作為一種表面形變強(qiáng)化的新方法,其原理是運(yùn)用激光高能脈沖誘導(dǎo)產(chǎn)生的高幅沖擊波壓力,在極短的時(shí)間內(nèi)作用于金屬靶材表面并使之發(fā)生超高應(yīng)變速率的塑性變形,有效地改善金屬材料的應(yīng)力分布狀態(tài)并優(yōu)化微觀組織結(jié)構(gòu),達(dá)到抑制腐蝕疲勞斷裂過(guò)程并提升零部件有效服役壽命的目的。針對(duì)上述所存在的問(wèn)題,本文以2Cr13馬氏體不銹鋼為探究對(duì)象,通過(guò)對(duì)激光沖擊強(qiáng)化不銹鋼抗腐蝕疲勞特性進(jìn)行理論探討,分析研究了不同層數(shù)激光沖擊強(qiáng)化對(duì)腐蝕疲勞性能的影響。將宏觀機(jī)械性能和微觀斷口形貌相結(jié)合,詳盡地闡明了激光沖擊強(qiáng)化的延壽作用,進(jìn)一步建立了對(duì)應(yīng)殘余應(yīng)力場(chǎng)數(shù)值的仿真模擬。獲得了如下的結(jié)論和進(jìn)展:(1)完成了以ABAQUS軟件為基礎(chǔ)的數(shù)字化分析,可視化地獲得了激光沖擊強(qiáng)化仿真應(yīng)力場(chǎng)的分布,結(jié)合模擬來(lái)研究應(yīng)力對(duì)裂紋的抑制性。同時(shí)仿真分析的結(jié)果也可以用來(lái)進(jìn)行不銹鋼腐蝕疲勞裂紋擴(kuò)展特性的預(yù)測(cè)。經(jīng)過(guò)激光沖擊強(qiáng)化,模型表面應(yīng)力狀態(tài)發(fā)生了明顯改變,并產(chǎn)生了塑性變形,沖擊強(qiáng)化誘導(dǎo)產(chǎn)生了表面殘余壓應(yīng)力,同時(shí)也造成了內(nèi)部拉應(yīng)力,經(jīng)過(guò)雙面激光沖擊強(qiáng)化,模型截面的殘余應(yīng)力場(chǎng)呈現(xiàn)對(duì)稱式分布。(2)通過(guò)試驗(yàn)具體分析了不同激光沖擊層數(shù)、腐蝕介質(zhì)濃度對(duì)腐蝕疲勞壽命的影響,探索了腐蝕疲勞裂紋擴(kuò)展的變化。通過(guò)對(duì)數(shù)據(jù)進(jìn)行分析處理,獲得了裂紋擴(kuò)展曲線a-N、擴(kuò)展速率曲線da/dN-ΔK等,定性揭示了裂紋擴(kuò)展規(guī)律。激光沖擊強(qiáng)化處理以后,腐蝕疲勞壽命增幅達(dá)到了30%~50%;裂紋的擴(kuò)展速率隨著激光沖擊層數(shù)的增加而減小。而腐蝕介質(zhì)濃度提高會(huì)增大材料的斷裂脆性并導(dǎo)致材料壽命的縮短;依據(jù)Paris公式求取了激光沖擊強(qiáng)化不銹鋼材料常數(shù)的改變規(guī)律,得到了激光沖擊對(duì)不銹鋼腐蝕疲勞壽命的增益機(jī)制。(3)深入探討了不銹鋼腐蝕疲勞斷口形貌特性,系統(tǒng)地分析了斷口宏微觀特征以及強(qiáng)化改善機(jī)理。根據(jù)局部塑性變形的差異,重建了從裂紋開(kāi)始到最終斷裂的微觀順序。未沖擊基體斷裂面比較平滑,激光沖擊強(qiáng)化后的斷面變得粗糙不平坦,產(chǎn)生了加倍彎曲轉(zhuǎn)折的裂紋擴(kuò)展路徑,同時(shí)出現(xiàn)了疲勞臺(tái)階、微觀變形及撕裂棱等現(xiàn)象,并損耗了應(yīng)變能,降低了裂紋擴(kuò)展速率,起到了阻滯作用。對(duì)比了斷口主要元素含量的變化,經(jīng)過(guò)激光沖擊強(qiáng)化后材料的腐蝕程度降低了,增加沖擊層數(shù)可以進(jìn)一步降低腐蝕程度。(4)研究了激光沖擊強(qiáng)化不銹鋼的機(jī)械性能及表面完整性。分析了表面形貌和粗糙度變化:材料表面的塑性變形量隨激光沖擊強(qiáng)化層數(shù)的增加而增大,抗塑性變形能力也得到了顯著強(qiáng)化,可以更好地承受外加載荷。探究了激光沖擊強(qiáng)化后殘余壓應(yīng)力場(chǎng)的分布:殘余壓應(yīng)力值隨激光沖擊層數(shù)的增加而增大并趨于飽和,殘余壓應(yīng)力有效地抑制了表面裂紋萌生并降低了裂紋擴(kuò)展速率,形成了擴(kuò)展抗力并以此改善了抗腐蝕疲勞性能。綜上所述,本文研究為實(shí)際應(yīng)用中如何改善關(guān)鍵零部件的抗腐蝕疲勞性能提供了一種新思路,為深入了解激光沖擊強(qiáng)化2Cr13不銹鋼的表面機(jī)械性能改善提供了參考,為系統(tǒng)揭示激光沖擊強(qiáng)化對(duì)2Cr13不銹鋼表面塑性變形和強(qiáng)化機(jī)制,提供了可供參考的理論與試驗(yàn)依據(jù)。
[Abstract]:In today's industrial production practices, many of the key locations are limited to their complex corrosive service environments and are subject to cyclic and alternating loads that often result in destructive accidents due to corrosion fatigue fracture. One of the core scientific problems in the re-manufacturing of modern mechanical components is how to use advanced surface treatment technology to strengthen the key parts, prolong the service life and improve the reliability of its use. The invention relates to a new method for strengthening surface deformation by laser shock strengthening, which is characterized in that the high-amplitude shock wave pressure generated by laser high-energy pulse induction is applied to the surface of the metal target material in a very short time and the high strain rate is plastically deformed, The stress distribution state of the metal material is effectively improved and the microstructure of the microstructure is optimized, and the purpose of inhibiting the corrosion fatigue fracture process and improving the effective service life of the component is achieved. In the light of the above problems, this paper makes a theoretical study on the corrosion fatigue characteristics of laser shock-reinforced stainless steel by using 2Cr13 Martensitic stainless steel as the research object, and analyzes the effect of laser shock strengthening on the corrosion fatigue property of different layers. In this paper, the macro-mechanical property and the micro-fracture morphology are combined, the life-prolonging effect of the laser shock strengthening is explained in detail, and the simulation of the corresponding residual stress field is further established. The following conclusions and progress have been obtained: (1) The digital analysis based on the ABAQUS software is completed, and the distribution of the laser shock-enhanced simulated stress field is obtained and the suppression of the stress on the crack is studied in combination with the simulation. At the same time, the results of the simulation analysis can also be used to predict the corrosion fatigue crack growth of the stainless steel. Through the laser shock strengthening, the stress state of the model surface is obviously changed, the plastic deformation is generated, the impact strengthening induction generates the surface residual compressive stress, and the internal tensile stress is also caused, and the double-sided laser shock strengthening is carried out, The residual stress field of the model section presents a symmetric distribution. (2) The effects of different laser shock layers and corrosion medium concentration on the corrosion fatigue life were analyzed, and the change of corrosion fatigue crack propagation was investigated. By analyzing the data, the crack propagation curve a-N, the extension rate curve da/ dN-K and the like are obtained, and the crack propagation rule is revealed. The increase of the corrosion fatigue life is 30% ~ 50% after the laser shock-strengthening treatment, and the crack growth rate decreases with the increase of the number of laser shock layers. The increase of the concentration of the corrosion medium increases the fracture and brittleness of the material and leads to the shortening of the life of the material. The change of the constant of the laser shock-reinforced stainless steel material is obtained according to the Paris formula, and the gain mechanism of the laser shock on the fatigue life of the stainless steel is obtained. (3) The characteristics of the fracture morphology of the corrosion fatigue fracture of the stainless steel are discussed, and the micro-characteristics of the fracture and the strengthening mechanism of the fracture are systematically analyzed. The micro order from the beginning of the crack to the final fracture is re-established according to the difference of the local plastic deformation. the fracture surface of the non-impact substrate is relatively smooth, the cross section after the laser shock strengthening becomes rough and uneven, the crack propagation path of the double bending transition is generated, the phenomena of fatigue steps, micro-deformation and tearing edges and the like are generated, the strain energy is lost, the crack growth rate is reduced, And has a blocking effect. The change of the main element content of the fracture is compared, the corrosion degree of the material after the laser shock strengthening is reduced, and the corrosion degree can be further reduced by increasing the number of the impact layers. (4) The mechanical properties and surface integrity of laser shock-reinforced stainless steel were studied. The change of surface morphology and roughness is analyzed. The plastic deformation of the surface of the material is increased with the increase of the number of the laser shock-enhancing layers, and the anti-plastic deformation capability is greatly enhanced, and the applied load can be better borne. The distribution of residual compressive stress field after laser shock strengthening is explored. The residual compressive stress value increases with the increase of the number of laser shock layers and tends to be saturated. The residual compressive stress effectively inhibits the surface crack initiation and reduces the crack growth rate. The extension resistance is formed and the anti-corrosion fatigue property is improved. To sum up, this paper provides a new idea for how to improve the corrosion fatigue performance of key parts in practical application, and provides a reference for the in-depth understanding of the improvement of the surface mechanical properties of the laser shock-reinforced 2Cr13 stainless steel. The plastic deformation and strengthening mechanism of the surface of the 2Cr13 stainless steel is revealed by laser shock strengthening for the system, and the theoretical and experimental basis for reference is provided.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG142.71;TG665

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 王江濤;張永康;陳菊芳;周金宇;盧雅琳;張朝陽(yáng);;強(qiáng)激光沖擊對(duì)7075鋁合金等離子弧焊接頭電化學(xué)腐蝕行為的影響[J];中國(guó)激光;2015年12期

2 李興成;盧雅琳;周金宇;陳菊芳;;激光沖擊AZ31鎂合金的腐蝕疲勞特性研究[J];機(jī)械科學(xué)與技術(shù);2015年11期

3 黃群慧;賀俊;;中國(guó)制造業(yè)的核心能力、功能定位與發(fā)展戰(zhàn)略——兼評(píng)《中國(guó)制造2025》[J];中國(guó)工業(yè)經(jīng)濟(jì);2015年06期

4 汪誠(chéng);賴志林;何衛(wèi)鋒;薛彥慶;周留成;;激光沖擊次數(shù)對(duì)1Cr11Ni2W2MoV不銹鋼高周疲勞性能的影響[J];中國(guó)激光;2014年01期

5 羅開(kāi)玉;陳起;呂刺;劉娟;林通;;雙面激光同時(shí)沖擊AM50鎂合金板料的厚度分析[J];中國(guó)激光;2014年01期

6 任維彬;董世運(yùn);徐濱士;王玉江;閆世興;方金祥;;Fe314合金激光熔覆層的應(yīng)力分布規(guī)律[J];中國(guó)表面工程;2013年03期

7 徐慶東;林鑫;宋夢(mèng)華;楊海歐;黃衛(wèi)東;;激光成形修復(fù)2Cr13不銹鋼熱影響區(qū)的組織研究[J];金屬學(xué)報(bào);2013年05期

8 鐘俊偉;魯金忠;羅開(kāi)玉;楊超君;戴峰澤;鐘金杉;王慶偉;齊晗;張磊;;AISI 8620合金鋼激光沖擊強(qiáng)化層摩擦學(xué)特性[J];中國(guó)激光;2012年01期

9 陳志坤;劉敏;曾德長(zhǎng);馬文有;;激光熔覆裂紋的產(chǎn)生原因及消除方法探究[J];激光雜志;2009年01期

10 張永康;陳菊芳;許仁軍;;AM50鎂合金激光沖擊強(qiáng)化實(shí)驗(yàn)研究[J];中國(guó)激光;2008年07期

相關(guān)博士學(xué)位論文 前3條

1 黃舒;激光噴丸強(qiáng)化鋁合金的疲勞裂紋擴(kuò)展特性及延壽機(jī)理研究[D];江蘇大學(xué);2012年

2 陳菊芳;AM50鎂合金表面激光改性研究[D];江蘇大學(xué);2008年

3 王衛(wèi)國(guó);輪盤低循環(huán)疲勞壽命預(yù)測(cè)模型和試驗(yàn)評(píng)估方法研究[D];南京航空航天大學(xué);2006年

相關(guān)碩士學(xué)位論文 前3條

1 于水生;AZ31B鎂合金中強(qiáng)激光誘發(fā)沖擊波的實(shí)驗(yàn)研究及數(shù)值模擬[D];江蘇大學(xué);2010年

2 裴旭;AZ91鎂合金激光沖擊力學(xué)性能及表層材料結(jié)構(gòu)變化效應(yīng)研究[D];江蘇大學(xué);2010年

3 李東;轉(zhuǎn)子系統(tǒng)若干故障問(wèn)題的非線性及可靠性分析[D];東北大學(xué);2008年

，

本文編號(hào)：2496830