發(fā)布時間：2018-08-25 16:58

【摘要】：激光熔化沉積技術借助大功率激光技術及CAD/CAM技術可以實現(xiàn)復雜結構金屬零部件的快速無模近成形,不僅能大幅縮減產(chǎn)品開發(fā)周期還能最大程度上節(jié)約原材料。然而由于缺乏規(guī)范的工藝標準,成形件常出現(xiàn)內(nèi)部孔隙、裂紋等缺陷,嚴重制約了其在更廣泛領域的應用。交變磁場能在其附近導體內(nèi)產(chǎn)生感應電磁力,使導體發(fā)生塑性變形。這一原理已被廣泛應用在金屬成形領域。本文借鑒電磁成形的工藝技術,旨在利用感生的電磁力使工件產(chǎn)生塑性變形,抵消工件因冷卻收縮產(chǎn)生的拉伸應變,從而達到降低殘余應力幅值,抑制熱裂紋生長的目的。主要完成工作如下:(1)從理論方面系統(tǒng)分析了激光熔化沉積殘余應力產(chǎn)生的機理以及電磁優(yōu)化激光熔化沉積的機理,包括降低殘余應力和細化枝晶組織的機理。(2)基于ANSYS平臺,模擬了電磁輔助激光熔化沉積過程。研究了單一激光熔化沉積的殘余應力在時間和空間上的分布,并分析了固定電磁力對殘余應力的影響以及不同電磁力大小的影響規(guī)律。(3)搭建試驗裝置,并開展了激光熔化沉積單道單層試驗,制備了金相樣件,對制造件內(nèi)部晶粒組織進行了觀察分析。(4)在激光熔化沉積單道單層的基礎上,進行了多道多層試驗。使用X射線衍射法測量工件表面殘余應力,并結合電解腐蝕的方法對深度方向的殘余應力進行了測量。本文通過APDL編程語言實現(xiàn)了溫度場、應力場和電磁場的三場耦合。利用該仿真模型不僅研究了殘余應力的分布情況,而且分析了電磁場對殘余應力的影響規(guī)律,仿真結果與后期試驗取得了較好的一致性,為后期進一步的工藝研究奠定了基礎。
[Abstract]:Laser melting deposition technology can realize the rapid formability of metal parts with complex structure by means of high power laser technology and CAD/CAM technology. It can not only greatly reduce the product development cycle but also save the raw materials to the greatest extent. However, due to the lack of standard process standards, defects such as internal pores and cracks often occur in forming parts, which seriously restrict its application in a wider field. The alternating magnetic field can produce inductive electromagnetic force in the nearby conductor, which causes plastic deformation of the conductor. This principle has been widely used in the field of metal forming. Using the technology of electromagnetic forming for reference, the purpose of this paper is to make use of the induced electromagnetic force to make the workpiece produce plastic deformation, to counteract the tensile strain caused by cooling shrinkage of the workpiece, so as to reduce the amplitude of residual stress and restrain the growth of hot crack. The main works are as follows: (1) the mechanism of laser melt deposition residual stress and the mechanism of electromagnetic optimization of laser melting deposition are analyzed theoretically, including the mechanism of reducing residual stress and refining dendrite structure. (2) based on ANSYS platform, The electromagnetic assisted laser melting deposition process was simulated. The distribution of residual stress in time and space of single laser melting deposition is studied, and the influence of fixed electromagnetic force on residual stress and the influence of different electromagnetic force are analyzed. (3) A test device is built. The single channel single layer experiment of laser melting deposition was carried out and the metallographic sample was prepared. The grain structure in the fabrication part was observed and analyzed. (4) on the basis of laser melting deposition single channel monolayer, multichannel and multilayer tests were carried out. The residual stress of workpiece surface was measured by X-ray diffraction method and the residual stress in depth direction was measured by electrolytic corrosion method. In this paper, the coupling of temperature field, stress field and electromagnetic field is realized by APDL programming language. The simulation model is used not only to study the distribution of residual stress, but also to analyze the influence of electromagnetic field on residual stress. The simulation results are in good agreement with the later test results, which lays a foundation for further technological research in the later stage.
【學位授予單位】：南京航空航天大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG665

【參考文獻】

相關期刊論文 前10條

1 楊光;丁林林;王向明;王華明;欽蘭云;;掃描路徑對激光修復鈦合金殘余應力與變形的影響[J];紅外與激光工程;2015年10期

2 董世運;閆曉玲;徐濱士;;微觀組織及殘余應力對瑞利波評價激光熔覆層應力的影響[J];機械工程學報;2015年24期

3 李桂榮;王宏明;李沛思;高雷章;彭琮翔;鄭瑞;;磁致塑性效應下的位錯動力學機制[J];物理學報;2015年14期

4 王宏明;李沛思;鄭瑞;李桂榮;袁雪婷;;強脈沖磁場沖擊處理對鋁基復合材料塑性的影響機制[J];物理學報;2015年08期

5 趙劍峰;馬智勇;謝德巧;韓雪謙;肖猛;;金屬增材制造技術[J];南京航空航天大學學報;2014年05期

6 王華明;;高性能大型金屬構件激光增材制造:若干材料基礎問題[J];航空學報;2014年10期

7 王洋;張述泉;劉長猛;湯海波;;激光熔化沉積TC18鈦合金組織及缺口高周疲勞性能[J];金屬熱處理;2013年05期

8 劉云雷;趙劍峰;潘滸;王凱;肖猛;;基于激光熔覆的鎳基高溫合金激光修復的數(shù)值模擬[J];應用激光;2013年02期

9 孫方遒;;宏觀殘余應力X射線測定[J];煤炭技術;2012年12期

10 孔源;劉偉軍;王越超;趙宇輝;來佑彬;;掃描方式對激光直接成形過程中熱力耦合場與殘余應力分布的影響[J];激光與光電子學進展;2012年05期

相關博士學位論文 前2條

1 徐達;外加電磁場控制焊接變形及冷裂紋研究[D];哈爾濱工業(yè)大學;2011年

2 張興國;電磁鑄造技術的研究[D];大連理工大學;2001年

相關碩士學位論文 前2條

1 王本龍;電磁沖擊控制焊接應力應變的研究[D];長春理工大學;2010年

2 劉金艷;X射線殘余應力的測量技術與應用研究[D];北京工業(yè)大學;2009年

，

本文編號：2203531