本文選題：激光沖擊強(qiáng)化 + AM50鎂合金��； 參考：《江蘇大學(xué)》2016年碩士論文

【摘要】：鎂合金因其密度小,比強(qiáng)度高、導(dǎo)熱性好、尺寸穩(wěn)定性高、阻尼特性高等特點(diǎn),廣泛應(yīng)用于航空航天、運(yùn)輸、汽車等工業(yè)領(lǐng)域。由于鎂合金表面強(qiáng)度和硬度較低、耐磨性差,嚴(yán)重阻礙了鎂合金在工程上的應(yīng)用。因此,提高鎂合金的表面性能已經(jīng)成為重要構(gòu)件制造中的關(guān)鍵問題之一。表面處理技術(shù)能夠通過改善鎂合金表層組織結(jié)構(gòu),從而提高鎂合金整體的機(jī)械性能。激光沖擊強(qiáng)化(LSP:Laser Shock Processing)是一種新型的表面處理技術(shù),被廣泛應(yīng)用于金屬表面改性,其最大的特點(diǎn)是通過高能量激光脈沖誘導(dǎo)的高強(qiáng)度沖擊波在金屬表面產(chǎn)生較深的殘余壓應(yīng)力層。實(shí)現(xiàn)長壽命關(guān)鍵件抗疲勞制造是使我國從機(jī)械制造大國邁向機(jī)械制造強(qiáng)國的必由之路,是我國的戰(zhàn)略舉措和緊迫需求。2015年我國提出的《中國制造2025》行動(dòng)綱領(lǐng)明確將激光先進(jìn)制造列為“前沿技術(shù)”。針對(duì)以上現(xiàn)狀,本文開展壓鑄鎂合金激光沖擊強(qiáng)化應(yīng)力場和拉伸性能的研究,獲得的一些主要結(jié)論和創(chuàng)新性成果如下:(1)利用有限元軟件ABAQUS分析研究不同激光沖擊路徑對(duì)AM50鎂合金殘余應(yīng)力場的影響規(guī)律以及雙面同時(shí)沖擊與雙面間隔沖擊之間的差異。在建立三維拉伸試樣分析模型后,對(duì)比分析不同模型厚度方向和表面的殘余應(yīng)力分布,得出最佳的激光沖擊方式。結(jié)果表明:當(dāng)激光參數(shù)保持不變時(shí),激光沖擊強(qiáng)化雖然能在AM50鎂合金表層誘導(dǎo)高幅值的殘余壓應(yīng)力,但也會(huì)在材料內(nèi)部產(chǎn)生不好的殘余拉應(yīng)力;雙面同時(shí)沖擊誘導(dǎo)出的殘余壓應(yīng)力場在板料沿厚度方向的中間區(qū)域不僅有殘余拉應(yīng)力存在,還有一定的壓應(yīng)力;激光沖擊路徑垂直于拉伸力方向所誘導(dǎo)的表面殘余應(yīng)力分布更均勻、波動(dòng)性更小、平均殘余應(yīng)力值更大、強(qiáng)化效果更好。另外,雖然雙面激光間隔沖擊在試樣上表面誘導(dǎo)的殘余壓應(yīng)力最大值更大一些,但是雙面激光同時(shí)沖擊誘導(dǎo)出的殘余壓應(yīng)力場在深度方向上結(jié)構(gòu)對(duì)稱,上下表面殘余應(yīng)力的一致性更好。綜上可得最優(yōu)的激光沖擊強(qiáng)化AM50鎂合金拉伸試樣方式是:雙面同時(shí)激光沖擊處理,且沖擊路徑垂直于拉伸力方向。(2)采用高能納秒激光束對(duì)鎂合金拉伸試樣進(jìn)行變面積激光沖擊強(qiáng)化處理,研究沖擊面積對(duì)應(yīng)力-應(yīng)變曲線的影響,結(jié)合斷口形貌分析,獲得沖擊面積與拉伸裂紋萌生位置的關(guān)系模型。對(duì)比分析不同激光沖擊覆蓋面積下試樣的應(yīng)力-應(yīng)變曲線,基于斷口形貌和裂紋位置系統(tǒng)研究激光沖擊面積對(duì)試樣拉伸性能的影響機(jī)理,得出雙面激光沖擊強(qiáng)化AM50鎂合金平板拉伸試樣的最佳覆蓋面積。結(jié)果表明:大面積激光沖擊強(qiáng)化使得拉伸試樣的抗拉強(qiáng)度和屈服強(qiáng)度得到明顯提升,且抗拉強(qiáng)度和屈服強(qiáng)度隨著沖擊面積的增加而增加。然而,拉伸試樣的塑性(包括斷后伸長率和斷面收縮率)隨著激光沖擊面積的增加先增加后減小。當(dāng)激光沖擊長度從0 mm(LSP-0)增加到40 mm(LSP-40)時(shí),裂紋萌生位置由中間向兩邊轉(zhuǎn)移再回到中間,由于不同激光沖擊覆蓋面積下裂紋萌生位置的轉(zhuǎn)移,試樣斷裂模式發(fā)生從脆性斷裂向韌性斷裂的轉(zhuǎn)變。(3)微觀表征和對(duì)比鎂合金激光沖擊前后表層微觀組織,獲得沖擊面積對(duì)AM50鎂合金試樣拉伸性能的影響規(guī)律。通過對(duì)激光沖擊區(qū)域微觀組織的觀測獲得激光沖擊AM50鎂合金表層晶粒細(xì)化過程。研究微觀結(jié)構(gòu)對(duì)試樣拉伸性能的影響機(jī)理,較好的解釋試樣拉伸性能變化的原因。結(jié)果表明,大面積激光沖擊AM50鎂合金上表層晶粒細(xì)化過程示意性地描述如下:(i)由于超高能量激光沖擊波的機(jī)械作用,在平均晶粒大小為50μm的粗晶中產(chǎn)生了一些變形孿晶,兩個(gè)相鄰變形孿晶的間隔長度大約為5μm;(ii)沿一個(gè)方向的變形孿晶將原始粗晶劃分為T-M薄片;(iii)T-M薄片隨機(jī)演化成平均大小5μm的細(xì)化晶粒。隨著激光沖擊面積的增加,晶粒細(xì)化的區(qū)域也逐漸擴(kuò)大,使得裂紋萌生位置發(fā)生轉(zhuǎn)移,從而導(dǎo)致AM50鎂合金試樣拉伸性能隨激光沖擊覆蓋面積的變化而變化。激光沖擊強(qiáng)化作為新型的材料表面強(qiáng)化技術(shù),不僅可以在材料表層誘導(dǎo)出高幅值的殘余壓應(yīng)力,也能明顯細(xì)化表層晶粒。由于殘余壓應(yīng)力層和晶粒細(xì)化層的共同作用,AM50鎂合金試樣的拉伸性能得到顯著提升,裂紋萌生位置隨激光沖擊覆蓋面積的變化而發(fā)生轉(zhuǎn)移。
[Abstract]:Magnesium alloy has low density, high strength, good thermal conductivity, high dimensional stability and high damping characteristics. It is widely used in aerospace, transportation, automobile and other industrial fields. Because of low surface strength and hardness and poor wear resistance of magnesium alloy, magnesium alloy has been seriously hindered the application of magnesium alloy in Engineering. Therefore, the surface properties of magnesium alloys have been improved. As one of the key problems in the manufacturing of important components, surface treatment technology can improve the mechanical properties of magnesium alloy by improving the structure of magnesium alloy surface, and laser impact strengthening (LSP:Laser Shock Processing) is a new type of surface treatment technology, which is widely used in the surface modification of metal. High intensity laser pulses induced by high energy laser pulses produce a deep residual compressive stress layer on the metal surface. It is the only way for China to make our country from a large machinery manufacturing country to a powerful mechanical manufacturing country. It is a strategic measure in China and an urgent need to seek China's 2025> line made in.2015. The dynamic program explicitly lists advanced laser manufacturing as "frontier technology". Aiming at the above situation, this paper studies the stress field and tensile properties of laser shock strengthening of die casting magnesium alloy. Some main conclusions and innovative achievements are obtained as follows: (1) the study of AM50 magnesium alloy residue by different laser impact paths by the finite element software ABAQUS The influence of the stress field and the difference between the double side impact and the double-sided spacer impact. After establishing the three-dimensional tensile specimen analysis model, the distribution of the residual stress in the thickness direction and the surface of the different models is compared and analyzed. The results show that the laser shock enhancement is not constant when the excitation parameters remain unchanged. The residual compressive stress of high amplitude can be induced on the surface of AM50 magnesium alloy, but the residual tensile stress is produced inside the material, and the residual compressive stress field induced by double side impact at the same time has not only residual tensile stress but also some compressive stress in the middle area along the thickness direction of the sheet material, and the laser impact path is perpendicular to the direction of tensile force. The induced surface residual stress distribution is more uniform, the fluctuation is smaller, the average residual stress is higher and the strengthening effect is better. In addition, although the double-sided laser spacing impact on the sample surface induces the maximum residual compressive stress, but the residual compressive stress field induced by double side laser at the same time is structured in the depth direction. It is said that the consistency of the residual stress on the upper and lower surfaces is better. The best way to obtain the best laser impact strengthening AM50 magnesium alloy tensile specimen is double-sided laser shock treatment, and the impact path is perpendicular to the tensile force direction. (2) high energy nanosecond laser beam is used to improve the tensile test of magnesium alloy. The relation model of the impact area and the initiation position of the tensile crack was obtained by the effect of the area corresponding to the stress strain curve. The stress strain curve of the specimen under the different laser impact coverage area was compared and analyzed. The influence mechanism of the laser impact area on the tensile properties of the specimen was studied on the basis of the fracture morphology and the crack position system. The results show that the tensile strength and yield strength of the tensile specimen are greatly enhanced by the large area laser shock strengthening, and the tensile strength and yield strength increase with the increase of the impact area. However, the plasticity of the tensile specimens (including the after fracture) is increased. When the laser impact area increases, the length of the laser impact increases first and then decreases. When the laser impact length increases from 0 mm (LSP-0) to 40 mm (LSP-40), the crack initiation position is transferred from the middle to the middle, and the fracture mode of the specimen occurs from brittleness due to the shift of the crack growth position under different laser impact coverage area. The transformation of fracture to ductile fracture. (3) microscopic characterization and comparison of microstructure of surface surface before and after laser impact of magnesium alloy, the influence of impact area on the tensile properties of AM50 magnesium alloy samples was obtained. The grain refinement process of laser shock AM50 magnesium alloy was obtained by observing the microstructure of laser shock region. The influence mechanism of the tensile properties of the sample is explained well. The results show that the grain refinement process on the surface of AM50 magnesium alloy with large area laser shock is described as follows: (I) some deformation twins are produced in the coarse grains with the average size of 50 mu m due to the mechanical action of the ultra high energy laser shock wave. The interval length of two adjacent deformed twins is about 5 m; (II) the original coarse grains are divided into T-M thin slices along the deformation twins in one direction; (III) T-M thin slices are randomly evolved into refined grains with an average size of 5 mu m. With the increase of the impact area of the laser, the region of grain refinement gradually expands, so that the crack initiation position is transferred, thus the transition of the crack initiation position is made. The tensile properties of AM50 magnesium alloy change with the change of the coverage area of laser shock. As a new material surface strengthening technology, laser shock strengthening can not only induce high amplitude residual compressive stress on the surface of the material, but also obviously refine the surface grain. Because of the joint action of the residual compressive stress layer and grain refining layer, AM50 The tensile properties of magnesium alloy samples were significantly improved, and the location of crack initiation shifted with the coverage of laser shock.

【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】：2016
【分類號(hào)】：TG249.2;TG665

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 張永康;余承業(yè);;激光沖擊提高航空材料的疲勞壽命概述[J];電加工;1993年05期

2 ;激光沖擊處理的新活力[J];激光與光電子學(xué)進(jìn)展;1996年12期

3 范靜怡;激光沖擊處理[J];激光與光電子學(xué)進(jìn)展;1997年04期

4 肖愛民,楊繼昌,張永康;激光沖擊強(qiáng)化原理及應(yīng)用概述[J];電加工與模具;2000年06期

5 全宏聲;激光沖擊強(qiáng)化提高構(gòu)件疲勞強(qiáng)度[J];材料工程;2001年12期

6 謝頌京;張偉;;激光沖擊效果的影響因素及其發(fā)展趨勢[J];新技術(shù)新工藝;2006年10期

7 馬壯;李應(yīng)紅;張永康;任旭東;張凌峰;;激光沖擊處理對(duì)304不銹鋼力學(xué)性能的影響[J];材料熱處理學(xué)報(bào);2007年03期

8 羅新民;馬輝;張靜文;張永康;;激光沖擊中的“應(yīng)變屏蔽”和“約束擊穿”[J];材料導(dǎo)報(bào);2010年05期

9 羅新民;苑春智;任旭東;陳康敏;張永康;;激光沖擊超高應(yīng)變率對(duì)鈦板形變微結(jié)構(gòu)的影響[J];材料熱處理學(xué)報(bào);2010年06期

10 徐國建;李挺;王虹;杭爭翔;邢飛;;激光沖擊處理的應(yīng)用[J];電焊機(jī);2010年11期

相關(guān)會(huì)議論文 前10條

1 吳先前;宋宏偉;魏延鵬;王曦;黃晨光;段祝平;;激光沖擊強(qiáng)化誘導(dǎo)的沖擊波壓力特征研究[A];第十屆全國沖擊動(dòng)力學(xué)學(xué)術(shù)會(huì)議論文摘要集[C];2011年

2 阮亮;張文武;焦俊科;;激光沖擊強(qiáng)化研究現(xiàn)狀與發(fā)展[A];第15屆全國特種加工學(xué)術(shù)會(huì)議論文集（下）[C];2013年

3 鄒世坤;吳樹輝;曹子文;費(fèi)群星;;激光沖擊處理焊接區(qū)在核反應(yīng)堆上的應(yīng)用[A];第13屆全國特種加工學(xué)術(shù)會(huì)議論文集[C];2009年

4 鄒世坤;曹子文;;鈦合金整體葉盤的激光沖擊強(qiáng)化[A];2009年先進(jìn)光學(xué)技術(shù)及其應(yīng)用研討會(huì)論文集（上冊）[C];2009年

5 汪誠;李應(yīng)紅;馬壯;趙雙成;周鑫;;航空部件激光沖擊強(qiáng)化系統(tǒng)與工藝研究[A];大型飛機(jī)關(guān)鍵技術(shù)高層論壇暨中國航空學(xué)會(huì)2007年學(xué)術(shù)年會(huì)論文集[C];2007年

6 任旭東;張永康;周建忠;李國杰;;激光沖擊提高鈦合金機(jī)械性能研究[A];光子科技創(chuàng)新與產(chǎn)業(yè)化——長三角光子科技創(chuàng)新論壇暨2006年安徽博士科技論壇論文集[C];2006年

7 任旭東;張永康;馮愛新;張西良;;激光沖擊中殘余應(yīng)力對(duì)鏈篦機(jī)零件裂紋的影響[A];2008全國功能材料科技與產(chǎn)業(yè)高層論壇論文集[C];2008年

8 胡永祥;姚振強(qiáng);;基于高斯過程回歸的激光沖擊加工可靠建模方法研究[A];第15屆全國特種加工學(xué)術(shù)會(huì)議論文集（下）[C];2013年

9 羅龍錦;任志強(qiáng);張宗林;;激光沖擊強(qiáng)化與噴丸提高不銹鋼疲勞性能對(duì)比研究[A];第十五屆中國科協(xié)年會(huì)第13分會(huì)場：航空發(fā)動(dòng)機(jī)設(shè)計(jì)、制造與應(yīng)用技術(shù)研討會(huì)論文集[C];2013年

10 聶祥樊;臧順來;何衛(wèi)鋒;;激光沖擊“殘余應(yīng)力洞”敏感性分析與抑制方法研究[A];中國力學(xué)大會(huì)——2013論文摘要集[C];2013年

相關(guān)重要報(bào)紙文章 前4條

1 記者 張梅;首條激光沖擊強(qiáng)化生產(chǎn)線落戶航空基地[N];陜西日?qǐng)?bào);2008年

2 張梅;中國首條激光沖擊強(qiáng)化生產(chǎn)線在西安落戶[N];陜西科技報(bào);2008年

3 陳軍;我國激光沖擊強(qiáng)化應(yīng)用技術(shù)取得重大突破[N];中國高新技術(shù)產(chǎn)業(yè)導(dǎo)報(bào);2009年

4 鄒世坤;激光沖擊強(qiáng)化：新一代抗疲勞表面強(qiáng)化技術(shù)[N];中國航空?qǐng)?bào);2013年

相關(guān)博士學(xué)位論文 前8條

1 魯金忠;激光沖擊強(qiáng)化鋁合金力學(xué)性能及微觀塑性變形機(jī)理研究[D];江蘇大學(xué);2010年

2 蘇孺;基于X射線衍射技術(shù)的金屬材料受限形變行為研究[D];北京理工大學(xué);2015年

3 鄭超;激光沖擊微成形工藝數(shù)值模擬及其實(shí)驗(yàn)研究[D];山東大學(xué);2011年

4 胡永祥;激光沖擊處理工藝過程數(shù)值建模與沖擊效應(yīng)研究[D];上海交通大學(xué);2008年

5 羅開玉;激光沖擊不銹鋼抗腐蝕性能及微觀強(qiáng)化機(jī)理研究[D];江蘇大學(xué);2012年

6 車志剛;微尺度激光沖擊強(qiáng)化金屬靶材數(shù)值模擬與實(shí)驗(yàn)研究[D];華中科技大學(xué);2009年

7 丁華;金屬板料激光沖擊變形機(jī)理及鋁板校形研究[D];江蘇大學(xué);2010年

8 葛茂忠;AZ31B變形鎂合金及其焊接件激光沖擊處理研究[D];江蘇大學(xué);2013年

相關(guān)碩士學(xué)位論文 前10條

1 殷開婷;激光沖擊微細(xì)塑性成形工藝研究[D];江蘇科技大學(xué);2015年

2 黃婉婉;稠油熱采智能轉(zhuǎn)換接頭設(shè)計(jì)及抗腐蝕性能研究[D];江蘇大學(xué);2016年

3 李振;基于激光沖擊的鈦合金小孔構(gòu)件殘余應(yīng)力分布及疲勞性能研究[D];江蘇大學(xué);2016年

4 宣婷;激光沖擊表面微造型的理論和實(shí)驗(yàn)研究[D];江蘇大學(xué);2016年

5 邵偉;激光沖擊強(qiáng)化對(duì)AZ80鎂合金微觀組織和電化學(xué)腐蝕的影響[D];江蘇大學(xué);2016年

6 徐士東;GH2036合金激光沖擊晶粒細(xì)化及耐腐蝕性能優(yōu)化研究[D];江蘇大學(xué);2016年

7 鮑士喜;耐熱馬氏體不銹鋼ЭП866激光沖擊強(qiáng)化組織與性能研究[D];江蘇大學(xué);2016年

8 邢佳;鎂合金激光沖擊植入納米SiC顆粒工藝與性能研究[D];江蘇大學(xué);2016年

9 王長雨;壓鑄鎂合金雙面激光沖擊強(qiáng)化殘余應(yīng)力和拉伸性能研究[D];江蘇大學(xué);2016年

10 杜金星;基于激光沖擊強(qiáng)化的擠壓模具延壽方法及機(jī)理研究[D];江蘇大學(xué);2016年

，

本文編號(hào)：1825707