發(fā)布時間：2018-06-16 06:21

  本文選題：選擇激光熔化 + 工藝參數(shù)　； 參考：《蘭州理工大學》2017年碩士論文

【摘要】：選擇激光熔化(SLM)技術可直接成形復雜結構的金屬零件,成為了快速成形制造(RPM)技術中最有前景的技術。但SLM技術的發(fā)展時間尚短,國內(nèi)基于該技術的基礎研究還比較少。因此,本文以提高SLM成形零件質(zhì)量為目的,對成形樣件的致密度和力學性能進行了系統(tǒng)研究。研究的具體內(nèi)容有:(1)單熔道成形規(guī)律的研究。以不同的線能量輸入密度作為工藝參數(shù),研究單熔道燒結表面質(zhì)量。結果表明:按燒結表面質(zhì)量可將其劃分為四個區(qū)域(未熔化區(qū)、部分熔化區(qū)、充分熔化區(qū)、過熔區(qū))。(2)工藝參數(shù)的優(yōu)化。實驗的工藝參數(shù)包括旋轉角度(α )、鋪粉厚度(h)、激光功率(P)、掃描速度(v)以及掃描間距(s)。優(yōu)化結果為:α=600,h=0.04mm,P=310W,v=960mm/s,s=0.13mm,此時樣件的致密度和力學性能最佳。(3)顯微組織和斷口形貌分析。觀察SLM成形零件的表面微觀形貌,其組織晶粒細小均勻,韌窩尺寸也均勻細小,這就表明樣件力學性能相對較高。綜合分析實驗結果,能量輸入密度φ=P/(vsh)可作為一個統(tǒng)一的參數(shù)來研究各工藝參數(shù)對樣件致密度和力學性能的影響,φ存在一個最優(yōu)值,此時,樣件的致密度和力學性能最佳,當能量輸入密度低于或高于該值,樣件的致密度、抗拉強度、屈服強度都有所下降,相應的延伸率會小幅度提升。(4) SLM成形零件中冶金缺陷的研究。SLM成形零件內(nèi)部的冶金缺陷降低其致密度和力學性能。冶金缺陷的形式有孔隙、裂紋、氧化物夾雜以及殘余應力等。優(yōu)化工藝參數(shù),可改善成形零件中存在的冶金缺陷。綜合而言,本文的研究結果,為進一步研究SLM成形零件的致密度和力學性能提供理論基礎。
[Abstract]:Laser melting technique (SLM) has become the most promising technology in rapid prototyping (RPM) because it can be directly used to form metal parts with complex structures. However, the development time of SLM technology is still short, and the basic research based on SLM technology is relatively few. Therefore, in order to improve the quality of SLM forming parts, the density and mechanical properties of the formed samples are studied systematically in this paper. The specific content of the study is the study of the forming law of the single melt channel. The surface quality of single channel sintering was studied with different input density of linear energy. The results show that it can be divided into four regions according to the quality of sintered surface (unmelted zone, partial melting zone, full melting zone, overmelting zone, etc.). The technological parameters of the experiment include rotation angle (偽), thickness of powder coating, laser power, scanning speed (v) and scanning spacing. The optimized results are as follows: (a) the density and mechanical properties of the samples are the best, and the microstructure and fracture morphology of the samples are analyzed. The microstructure and dimple size of SLM formed parts are fine and uniform, which indicates that the mechanical properties of the samples are relatively high. Synthetically analyzing the experimental results, the energy input density 蠁 P / v 路h) can be used as a unified parameter to study the effect of each process parameter on the density and mechanical properties of the sample. There is an optimum value 蠁, and the sample has the best density and mechanical properties. When the energy input density is below or above this value, the densification, tensile strength and yield strength of the sample are all decreased. The study of Metallurgical defects in the formed parts of SLM. The Metallurgical defects in the formed parts of SLM can reduce the density and mechanical properties of the formed parts. Metallurgical defects take the form of pores, cracks, oxide inclusions and residual stresses. The metallurgical defects in forming parts can be improved by optimizing process parameters. In general, the results of this paper provide a theoretical basis for further study of density and mechanical properties of SLM forming parts.
【學位授予單位】：蘭州理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG665

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本文編號：2025694