热处理温度对SLM成形316L不锈钢组织性能影响研究

使用选区激光熔化(SLM)技术制备316L不锈钢试样以及残余应力样件,采用光学显微镜、扫描电子显微镜（SEM,配备电子背散射衍射探头EBSD）、显微硬度计等研究不同热处理工艺对SLM成形316L的显微组织、显微硬度、力学性能以及残余应力的影响,得到最优热处理工艺。结果表明SLM制备制件组织致密,在最优热处理1 000℃、保温2 h制度下,试样的性能稳定,显微硬度及拉伸性能各向异性差异小,残余应力小。此研究为SLM成形316L不锈钢的力学性能优化及显微组织调控提供了强有力的基础。     

不同种类不锈钢临界折射纵波激励及声弹系数对比

首先介绍了临界折射纵波的应力检测原理，使用多频率探头分别对316L不锈钢、SLM316L不锈钢和304不锈钢进行了激励和验证，然后对比同频率临界折射纵波在不同种类不锈钢中的传播情况，最后对不同频率不同材料的声弹系数进行了标定。     

316L不锈钢多孔结构的选区激光烧结成型工艺研究

研究了一种新型的制备金属多孔结构技术-选区激光烧结,着重说明该技术的基本原理和工艺过程,并利用此制备技术对316L不锈钢粉末进行了激光烧结制备多孔材料的实验研究.利用SEM分析了316L不锈钢多孔试样的微观孔隙特征,并测定其孔隙率.结果表明,在较高的扫描速率下可获得孔径分布均匀、孔隙贯通性良好的多孔结构;随扫描速率逐渐提高,试样孔隙率和弹性模量呈上升趋势.     

选区激光熔化316L不锈钢疲劳损伤非线性超声检测研究

疲劳损伤是影响选区激光熔化316L不锈钢服役安全的重要问题,基于经典的非线性超声理论,研究了疲劳加载条件下选区激光熔化316L不锈钢超声检测非线性系数随疲劳周期的变化规律。试验结果表明,当选区激光熔化316L不锈钢产生疲劳损伤后,超声波检测信号中二次谐波幅值明显增大,且超声非线性系数随着疲劳周期的增加呈逐渐增长趋势。因此,采用非线性超声检测方法对选区激光熔化316L不锈钢疲劳损伤进行检测是可行的。     

碳元素含量对SLM成形316L不锈钢机械性能的影响

通过添加石墨碳粉改变SLM成形过程中316L不锈钢的碳元素含量,研究3D打印过程中不同碳含量对316L不锈钢微观结构和力学性能的影响。结果表明:随着碳含量的增加,不同碳含量的316L不锈钢的硬度也随之增加,而拉伸强度性能却随之先增大后减小。通过对断口形貌的观察发现,在低、中碳含量下的断裂状态为韧性断裂,而在高碳含量下的断裂为脆性断裂。这是由于碳元素所形成的碳化物在低含量阶段增强了不锈钢的拉伸性能,但随着碳含量增多,微裂纹所形成的缺陷逐渐起到主导地位,严重影响拉伸性能。     

凝胶注模成型用316L不锈钢浆料的制备

采用凝胶注模成型技术,以天然琼脂为凝胶体,选择合适的分散剂,对316L不锈钢浆料的制备进行了研究,分析了琼脂的凝胶化特性和不锈钢浆料的分散性与稳定性。结果表明:浆料中加入质量分数为0.7%的琼脂溶液,以聚丙烯酸钠做分散剂,分散剂用量(质量分数)为0.15%,选择pH值为10.0时,能够得到稳定的、悬浮性较好的316L不锈钢浆料,用此浆料成型后可烧结制备形状复杂的316L不锈钢制品。     

稳态磁场对激光熔注球形WC颗粒分布的影响机理研究

利用稳态磁场对金属流体的粘滞效应,在316L不锈钢基体上制备颗粒梯度分布的WC/316L复合涂层.为研究稳态磁场对激光熔注球形WC颗粒分布的影响机理,建立了考虑固液相变、流动以及洛伦兹力的熔注熔池多物理场模型,分析稳态磁场对流场,洛伦兹力分布以及等效黏度的影响.采用多颗粒动力学模型与熔池模型耦合计算,研究稳态磁场对熔池...     

超声表面冲击强化对316L不锈钢疲劳性能的影响

用超声冲击方法对试件表面进行改性,可以提高316L不锈钢性能。结合拉伸试验、高周疲劳试验、扫描电子显微镜(Scanning Electron Microscope, SEM)、X射线衍射(X-Ray Diffraction, XRD)及能量色散谱仪(Energy Dispersive Spectrometer, EDS),测试了316及316L不锈钢的疲劳性能和断裂特性。结果表明,含碳量稍低的316L不锈钢拉伸强度及疲劳强度也略低;表面超声冲击强化可提高该奥氏体不锈钢抗拉强度约19.7%,但韧性会有所降低。316、316L、冲击处理后316L三组材料的疲劳极限分别为209 MPa、204 MPa、254 MPa,均为本身抗拉极限的35%左右,拟合公式S=-64+0.45σ_b;含碳量高的316,其S-N曲线数据归一性更好,试样无侧边裂缝。疲劳断面显示,裂纹源萌生于异质相或非金属夹杂,裂纹沿晶扩展,裂纹扩展区的速度波动也归因异质相。超声冲击后316L的裂纹扩展速度明显降低,断面的起伏更大,瞬断速度更快。     

316L不锈钢增材成型件小孔钻削试验研究

为研究316L不锈钢增材成型件的制备并改善其小孔钻削工艺性,以316L不锈钢粉末为增材成型材料,采用激光熔覆技术在45钢表面制备得到了316L不锈钢增材成型件;利用光学显微镜观察分析了试件熔覆层截面显微组织,使用显微硬度计测试了熔覆层的显微硬度;搭建了钻削试验平台,采用单因素试验与正交试验相结合的试验方案,对传统工艺获得的316L不锈钢板材与316L不锈钢增材成型件进行了钻削对比试验;探究了钻削工艺参数对增材成型件钻削性能的影响规律以及最优的钻削工艺参数组合。结果发现,通过激光熔覆增材制造技术制备得到的316L增材成型件表面平整光滑,熔覆层与基体之间呈良好的冶金结合,熔覆层的硬度为570HV～610HV,是传统工艺获得的316L不锈钢板材硬度(约为200HV～300HV)的2倍左右; 316L不锈钢增材成型件的钻削轴向力远小于传统工艺获得的316L不锈钢板材的钻削轴向力。激光熔覆增材制造技术能显著提高材料硬度并改善其切削加工性能。     

316L不锈钢的车削精加工研究

笔者对316L不锈钢材料的切削加工特点进行分析,并从刀具材料的选用以及切削用量、切削液的选择3方面对316L不锈钢零件的车削精加工进行了分析和研究.     

Tribological Property of Selective Laser Melting–Processed 316L Stainless Steel against Filled PEEK under Water Lubrication

Abstract

As a 3D printing technology, selective laser melting has remarkable advantages such as high processing flexibility, high material utilization, and short production cycle. The applications of selective laser melting technology in industry have become quite extensive. There are many tribological studies on selective laser melting materials, but few based on water lubrication (Zhu, et al., Journal of Zhejiang University-Science A, 19(2), pp 95–110). In this article, the tribological properties of 316L stainless steel processed by selective laser melting and traditional methods have been studied under water lubrication. Polyether ether ketone (PEEK) filled with carbon fiber (CF)/polytetrafluoroethylene (PTFE)/graphite was selected as the counterpart. 316L stainless steel and PEEK are a tribopair commonly used in water hydraulics. This study is of great significance to the application of selective laser melting material of tribopairs in water hydraulics. Friction and wear tests were carried out on a pin-on-disc contact test apparatus under different operating conditions. The friction coefficient, specific wear coefficient, scanning electron microscopy (SEM) of the worn surface, and energy-dispersive spectroscopy (EDS) of the surface adhesions of the three tribopairs were measured and compared. The results revealed that the friction coefficient of the selective laser melting (SLM) 316L stainless steel was significantly higher than that of traditionally processed (TP) 316L stainless steel, which might be caused by the pores on the surface of SLM 316L stainless steel. Adhesion and cutting on the surface of SLM 316L stainless steel were also more serious, resulting in a higher specific wear coefficient of its counterpart PEEK composite compared to PEEK composite against TP 316L stainless steel.     

Study of mechanical properties of AISI 316 stainless steel processed by “selective laser melting”, following different manufacturing strategies

Considering additive manufacturing (AM) as a field of major interest, this paper is focused on the study of the mechanical properties and their variability with manufacturing orientation (anisotropy) for a metallic alloy manufactured by AM, using the technology of selective laser melting (SLM). This study has been performed on an austenitic stainless steel—AISI 316 L—used for many industrial fields as chemical, cellulose, and medical, among them. Finally, the obtained properties have been analyzed and compared, for this steel, to those properties standardized and tested for “wrought” products. In this paper, previously published results are complemented, as the mechanical tests have been performed in all the possible directions of manufacturing by SLM and not only in two main directions. High mechanical values have been obtained, especially yield strength (significantly improved, compared with wrought or cast products) while keeping high values of ductility and notch impact resistance. For widespread industrial acceptance, AM parts need to be produced to high tolerances and with well-understood mechanical properties, and the aim of this paper is to contribute to this objective.     

Investigation of creep behavior of 316L stainless steel produced by selective laser melting with various processing parameters

Journal of Mechanical Science and Technology - Creep behavior of 316L stainless steel was experimentally investigated using small punch (SP) specimens produced by the selective laser melting (SLM)...     

水泵叶轮在激光选区熔化成型加工中的几何误差研究

以316L不锈钢金属粉末为原料,利用激光选区熔化成型技术试制某潜水泵用叶轮。针对水泵叶轮激光选区熔化成型加工中出现的几何误差,分析水泵叶轮出现几何误差的原因。通过设计工艺试验,探究水泵叶轮在激光选区熔化成型加工中几何误差的产生规律,建立水泵叶轮的几何误差模型,确定引起水泵叶轮成型精度的主要因素有:切片处理产生的误差、激光深穿透产生的误差、外边框凸起产生的误差、材料收缩变形产生的误差、粉末的杂质引起误差和成型缸升降产生的误差,采用后处理和补偿成型缸位移量,解决水泵叶轮几何误差。研究结果表明:当成型缸位移量为0.02823 mm时,所成型的水泵叶轮加工精度符合制造要求。     

高压下β-Ti的结构稳定性、弹性和电子性能的第一性原理研究

应用第一性原理的方法, 研究了高压下β-Ti在0 K下的结构稳定性、 弹性和电子性能. 吉布斯自由能和电子态密度的研究表明, 随着压力的增加, β-Ti 的结构趋于稳定. β→β 的相变压强为 64.3 GPa, 这一计算结果与其它的理论结果 63.7 GPa 和实验结果 50 GPa相吻合. 弹性常数的计算表明, β-Ti 力学稳定的低压极限约为50 GPa, 该压力下的弹性模量约为30.01 GPa, 接近人体骨骼的弹性模量30 GPa. 另外, 讨论了不同压力下β-Ti体积模量B、 剪切模量G、 杨氏模量E、 泊松比β、 声速和韧性/脆性. 随着压力的增加, B, G, E增加, 但是β减小. B/G 计算表明, β-Ti具有良好的韧性.     

激光选区熔化技术及其在个性化医学中的应用

激光选区熔化是一种精密金属增材制造技术,可以成形任意复杂的功能零件。个性化医学用品需要具有个性化的几何外形和良好的生物性能,为了探究激光选区熔化在个性化医学用品中的应用,采用DiMetal系列激光选区熔化设备成形医用金属材料如316L不锈钢、CoCrMo合金、Ti6Al4V,并对医用金属材料成形致密度、成形力学性能和几何结构成形性进行了研究。通过个性化设计和DiMetal系列激光选区熔化设备,设计与制造了个性化牙冠、舌侧正畸托槽、手术模板、全膝置换股骨远端假体、股骨近端假体、颅骨修复体等医学用品。研究证明DiMetal系列激光选区熔化装备、工艺可用于个性化医学用品的快速制造,这为个性化医学用品的快速响应设计与制造提供了一种新的手段。     

316LN不锈钢低速率应变下的热变形行为

目前, 对316LN不锈钢在低速率应变下的热变形行为研究很少. 本文选用工业316LN不锈钢, 通过Gleeble-3800热模拟试验机进行了600-1 100 ℃温度下, 应变速率为3×10-3 s-1的热压缩试验, 得到了真应力-应变曲线. 通过分析真应力-应变曲线和试样的微观组织, 得到了如下结论: 1 000 ℃和稍高温度是适于低速率应变下316LN不锈钢加工的温度.     

人工软骨材料摩擦学特性的研究

为了改善现行人工关节的润滑性能,需采用全新的结构设计,研制具有良好的润滑性能的低弹性模量材料。本文用自行研制的振子式摩擦仪观测了生物相容性较好的三种聚合物材料,即硅橡胶,聚氨酯,聚乙烯醇水凝胶的摩擦系数和润滑机理。     

三维金属零件的电子束选区熔化成形

针对电子束选区熔化成形技术中金属粉末在高能电子束作用下容易溃散的特点,进行不同形状的316L不锈钢粉末的成形研究,得出既不溃散又具有较好成形性的粉末配比.针对成形过程中成形区域的温度场分布特点,提出成形件旋转法和多连通区域零件的薄层切割法,能较好地解决成形件第一条扫描线球化和成形区域不同部位所需温度不相同的问题,简化CAD模型的数据处理过程.在材料研究和工艺研究的基础上,制造出三维金属零件,层间为完全冶金结合,层内没有未熔颗粒和空洞,组织结构为均匀细小的蜂窝状枝晶组织,水平和垂直拉伸试样的极限强度和断后伸长率为600 MPa、40%和560 MPa、35%.     

Study on energy input and its influences on single-track,multi-track, and multi-layer in SLM

Energy input is crucial in the manufacturing of high-density metal part with smooth surface. In this article, the authors had studied the single-track, multi-track, and multi-layer and had obtained four types of typical tracks, including regular and thick shape, regular and thin shape, regular but occasionally broken shape, irregular and pre-balling shape. The analysis of single- and multi-track experiments showed that the regular and thin shape was the most suitable for selective laser melting (SLM) fabrication. Multi-track experiments proved that dense and smooth surface can be obtained when the overlapping rate was around 30% based on the regular- and thin-shaped track. As a result of the heat accumulation effect during multi-track and multi-layer fabrication, it was possible to obtain ideal track type with less energy input. In multi-layer experiment, the gradually thicken layer was the reason for the surface quality deterioration. The inter-layer stagger scanning strategy, which can improve the quality of the end-use part, was used in this experiment. By testing the 316 L stainless steel samples fabricated by the SLM process, the microstructure can be identified as composed of fine equiaxed and columnar grains, and the samples had higher tensile strength and hardness than castings of the same material, but with lower elongation. The experiments had proved that SLM process can directly produce high dense 316 L stainless steel part with smooth surface.