选择性激光烧结金属零件的后处理

概述了选择性激光烧结(SLS)金属零件的后处理对改善结构完整性和诱导材料变形的影响.介绍了后处理液相烧结温度和时间对材料性能的影响.叙述了热等静压工艺,并论述了它在金属SLS零件中的应用.使用结果表明,热等静压适用于获得几乎全密实的零件.     

选择性激光烧结零件的冷等静压塑性成形过程模拟(英文)

应用结合的选择性激光烧结和冷等静压技术快速制造金属零件。使用有限元方法预测零件的最终尺寸并降低成本;使用Drucker-Prager-Cap模型在ABAQUS软件中实现对选择性激光烧结零件的冷等静压过程的模拟。金属粉末的性质通过冷等静压实验测量。结果表明:橡胶包套和摩擦因数对零件的形状和尺寸影响很小;零件只有均匀收缩,没有明显的形状扭曲。实验与模拟结果符合得较好,这表明Drucker-Prager-Cap模型是模拟冷等静压过程的有效模型;通过模拟可以为选择性激光烧结零件的冷等静压成形过程提供有益的指导。     

间接选择性激光烧结与选择性激光熔化对比研究

采用选择性激光烧结（Selective laser sintering，SLS）和选择性激光熔化（Selective laser melting，SLM）工艺，分别进行了铁基合金粉末的快速成形试验，对比分析了SLS与SLM成形机理、相应的工艺参数以及它们对测试件成形过程、金相组织与力学性能的影响。结果表明：由于成形机理不同，相对于SLS技术，采用SLM能够制造高致密度、组织均匀、力学性能良好的金属零件，但容易出现翘曲变形、裂纹与球化现象。通过制定合适的材料与工艺参数能够避免上述缺陷。     

选择性激光烧结金属粉末瞬态温度场模拟

局部输入的集中移动热源造成了选择性激光烧结过程中温度场分布不均衡且不稳定,因此研究其温度场对掌握烧结过程中温度动态分布规律具有重要意义。在考虑了热传导、热辐射和热对流,材料的非线性热物性参数和相变潜热的作用下,建立了水雾化Fe多道烧结的三维有限元模型,采用ANSYS参数化设计语言(APDL)实现移动的高斯热源的加载。模拟结果表明:激光烧结过程中,在光斑中心前端存在着较大的温度梯度;光斑中心的温度高于金属粉末的熔点,烧结过程存在液相;粉床内部温度场在深度方向呈漏斗状阶梯分布,随烧结深度的增加,粉床内部的温度和温度梯度迅速衰减;同一烧结道各点的最高温度相对稳定,但随着烧结道的增加,各点最高温度都有小幅度增加的趋势,这是温度累加的结果。     

固态粉末的选择性激光烧结

本文阐述了固态粉末的选择性激光烧结的各种方法。讨论了激光器及其加工参数对固体粉末烧结的影响。     

纳米材料激光选择性烧结成形的研究

纳米材料由于颗粒尺寸微小,致使其产生一些特异的性能,在应用过程中,把纳米粉末材料成形为大体积的材料及成形纳米零件产生了巨大的困难,激光选择性地成形纳米材料是利用激光烧结能量信号,能迅速加热,剧冷的特性,最大限度地控制纳米材料在烧结过程中颗粒生长的纳米材料成形的方法。本研究中,在激光选择性烧结成形纳米材料Al2O3的基础上,对纳米材料烧结成形过程中产生的问题进行了分析与探讨。     

选择性激光烧结翘曲变形模拟

建立了烧结过程的温度场、弹性应力应变场的有限元计算模型,开发了C++模拟软件,模拟了选择性激光烧结(SLS)过程的温度、残余热应力的演化,以及最终的翘曲变形.提出的改进移动热源加载算法提高了计算速度.研究结果表明:激光烧结过程中温度场不均匀,导致了热应力的产生,进而使制件变形,制件的上下部分收缩不一致,从而向上翘曲.随...     

选择性激光烧结技术在医学上的应用

简述了选择性激光烧结技术(SLS)和熔化技术(SLM)的成型原理及其在生物医学领域的应用,重点介绍了SLS在医学模型、植入体和赝复体、组织工程支架及药物传送装置等方面的应用,并对SLS和SLM技术的研究与发展方向进行展望。     

选择性激光烧结快速成形制件翘曲变形的研究

翘曲变形对选择性激光烧结(SLS)成形精度的影响很大.通过在HRPS-ⅢA型成型机上进行快速成型试验,找出产生翘曲变形的根本原因;得到了激光扫描速度和激光功率、粉末预热温度等工艺参数对翘曲变形的影响规律;并提出了减小翘曲变形的有效措施.     

选择性激光烧结成型工艺参数研究

研究了烧结温度、激光功率和扫描速度对选择性激光烧结成型件精度及力学性能的影响。结果表明:适当调整选择性激光烧结成型机的激光功率和扫描速度及烧结温度,能有效提高成型件的精度及抗拉强度,在激光功率为24 W、扫描速度为2 500 mm/s、烧结温度为80℃时,成型件的尺寸精度为100±0.1 mm,抗拉强度为1.96 MPa。     

Forming Simulation and Experimental Verification of Combined Formation of Selective Laser Sintering and Cold Isostatic Pressing

Selective laser sintering (SLS) could manufacture complex parts rapidly which, however, have high porosity and low intensity. While the parts made by cold isostatic pressing have advantages of uniform structure without composition segregation, high-dimension precision and high density. However, it could not form high complex parts because of the difficulties in manufacturing bag. A combination of SLS and cold isostatic pressing is expected to use the advantages of the two methods and is an efficient way to make complicated parts rapidly. After SLS and cold isostatic pressing, dimensions of parts decrease and relative density increases. To predict final dimensions and density, the finite element simulations are performed for cold isostatic pressing. The results show the parts made from ball shape powder contract symmetrically. The simulation results agree with the achieved geometries within 4%. Comparisons are made with that parts made from irregular powder. The SEM pictures after SLS are also showed. This has an important indication to process of SLS and cold isostatic pressing forming.     

高能球磨和冷压烧结制备Cr-Mn-Mo-N无镍不锈钢

采用高能球磨结合高温渗氮方法制备了Cr18Mn12Mo3N无镍高氮不锈钢粉末,随后利用冷压烧结工艺获得了无镍高氮奥氏体不锈钢材料。结果表明：制备的高氮复合粉末近球形,具有良好的成形性;Cr18Mn12Mo3N不锈钢的最佳烧结温度为1250℃,相对密度达到97．1％,氮含量为0．79％（质量分数）;经过1150℃固溶处理水冷后能获得完全奥氏体组织,其钝化电位范围宽,点蚀电位高,抗点蚀性能显著优于316L不锈钢。     

Sliding Wear Characteristics and Corrosion Behaviour of Selective Laser Melted 316L Stainless Steel

Stainless steel is one of the most popular materials used for selective laser melting (SLM) processing to produce nearly fully dense components from 3D CAD models. The tribological and corrosion properties of stainless steel components are important in many engineering applications. In this work, the wear behaviour of SLM 316L stainless steel was investigated under dry sliding conditions, and the corrosion properties were measured electrochemically in a chloride containing solution. The results show that as compared to the standard bulk 316L steel, the SLM 316L steel exhibits deteriorated dry sliding wear resistance. The wear rate of SLM steel is dependent on the vol.% porosity in the steel and by obtaining full density it is possible achieve wear resistance similar to that of the standard bulk 316L steel. In the tested chloride containing solution, the general corrosion behaviour of the SLM steel is similar to that of the standard bulk 316L steel, but the SLM steel suffers from a reduced breakdown potential and is more susceptible to pitting corrosion. Efforts have been made to correlate the obtained results with porosity in the SLM steel.     

New Ferro Powder for Selective Laser Sintering of Dense Parts

The paper describes a new powder composition specially developed for selective laser sintering (SLS). The aim is to obtain a ferro powder that can be sintered without need for a (sacrificial) polymer binder and that results in quasi dense parts that do not need any post-processing like furnace sintering, infiltration or HIP. The powder is a mixture of different types of particles (Fe, Cu, Ni and Fe₃P). The composition and mixture ratio are justified by using phase diagrams. The powder has been tested using an own developed Nd: YAG SLS machine. The influence of process parameters (laser power, scan velocity, scan spacing and scan strategy) and the microstructural characteristics have been investigated. Attention is devoted to the binding mechanism (liquid phase sintering, through melting) and to the quality of resulting parts (density, balling effect,…).     

On Optimization of Surface Roughness of Selective Laser Melted Stainless Steel Parts: A Statistical Study

In this work, the effects of re-melting parameters for postprocessing the surface texture of Additively Manufactured parts using a statistical approach are investigated. This paper focuses on improving the final surface texture of stainless steel (316L) parts, built using a Renishaw SLM 125 machine. This machine employs a fiber laser to fuse fine powder on a layer-by-layer basis to generate three-dimensional parts. The samples were produced using varying angles of inclination in order to generate range of surface roughness between 8 and 20 µm. Laser re-melting (LR) as post-processing was performed in order to investigate surface roughness through optimization of parameters. The re-melting process was carried out using a custom-made hybrid laser re-cladding machine, which uses a 200 W fiber laser. Optimized processing parameters were based on statistical analysis within a Design of Experiment framework, from which a model was then constructed. The results indicate that the best obtainable final surface roughness is about 1.4 µm ± 10%. This figure was obtained when laser power of about 180 W was used, to give energy density between 2200 and 2700 J/cm² for the re-melting process. Overall, the obtained results indicate LR as a post-build process has the capacity to improve surface finishing of SLM components up to 80%, compared with the initial manufactured surface.     

SLS烧结参数对快速成型制件精度与强度的影响

选择性激光烧结是一种先进的快速制造技术，其烧结参数对制件的强度和精度有很大的影响。本通过对高分子粉末选择性激光烧结，研究了激光烧结工艺参数：激光功率、扫描速度、烧结间距、单层层厚对烧结件强度与精度的影响关系，并得到两组优化的工艺参数。     

2205双相不锈钢高温变形行为及微观组织的研究

利用热模拟试验机Thermecmastor-E进行了950～1200℃,应变速率0.1～10 s-1、应变量10%～60%条件下2205双相不锈钢的高温压缩试验,并观察了变形组织。根据测定的真应力-真应变曲线分析了不同应变、温度条件下的热变形激活能Q及其变形机制的变化。结果表明,随应变量的增加,试验钢的表观应力指数n和热变形激活能Q随之增加;热变形机制逐渐由动态回复过渡到动态再结晶。     

选择性激光烧结钼基复合粉末（TZM）制造金属零件

通过采用热熔胶包覆钼合金(TZM)粉末制备了选择性激光烧结用粉末材料,并利用间接SLS方法制备了钼合金粉末毛坯,经过脱脂、高温烧结和渗铜处理制造了致密的渗铜TZM合金材料,对零件毛坯的成型、后处理工艺及合金的显微组织和力学性能进行了研究.结果表明:高温烧结中Mo、Zr、Ti、C能够通过固相扩散形成Mo2C、Mo2Zr间隙相,同时还可形成固溶体(Mo,Ti),熔渗铜后的室温组织由基体Mo、Cu、间隙相Mo2C、Mo2Zr和固溶体(Mo.Ti)构成;合金材料的拉伸强度超过480 MPa,延伸率为0.52%.     

空间网格状多孔316不锈钢的选区激光熔化制备

制备出尺寸可控的空间网状金属多孔材料,对所制备的多孔材料进行组织分析.分析试样的微观结构,并讨论选区激光熔化多孔金属材料的成形机制及工艺参数对多孔结构特征的影响规律.结果表明:通过CAD制图确定扫描路径图,确定了骨架每根梁之间的扫描间距,决定了金属多孔材料的孔隙大小、孔隙形状及分布.制备出试件的每片薄壁、方孔分布均匀,孔隙大小统一且形状规则.骨架连接结点紧密,骨架的组织严密无开裂和弯曲现象.选区激光熔化制备空间网格状多孔材料骨架的形成机理分为颗粒表面局部熔化、形成金属熔池和粉末粘接三个阶段.     

粉末特性对选择性激光熔化成形不锈钢零件性能的影响研究

选择性激光熔化技术可直接成形高性能金属零件,是最具应用前景的快速成形技术之一.现有研究主要集中讨论工艺参数,忽略了材料特性的影响.以不锈钢粉末为试验材料,实施单道单层线扫描与多层块体成形试验,揭示粉末颗粒形状、粒度分布以及含氧量对制件性能的影响规律.粉末特性影响制件性能的机理可归结于对熔池质量及球化程度的影响,其中粉末...