316L Stainless Steel with Gradient Porosity Fabricated by Selective Laser Melting

Li, Ruidi; Liu, Jinhui; Shi, Yusheng; Du, Mingzhang; Zhan, Xie

doi:10.1007/s11665-009-9535-2

Cited by 208 publications

(116 citation statements)

References 14 publications

Supporting

Mentioning

112

Contrasting

Unclassified

Order By: Relevance

“…The purpose at that early phase was mainly to understanding the SLM process [120][121][122], and with the development of SLM process the focuses and aims gradually shift to exploring the possibilities of manufacturing high-value added components. The most commonly reported SLM iron-base alloys include 316L stainless steel [123][124][125][126][127][128].…”

Section: Materials Manufactured With Slmmentioning

confidence: 99%

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Deng

2018

Linköping Studies in Science and Technology. Licentiate Thesis

View full text Add to dashboard Cite

Linköping 2018Cover image: A fracture surface of EBM IN718 after tensile test at room temperature.During the course of research underlying this thesis, Dunyong Deng was enrolled in Agora Materiae, a multidiciplinary doctoral program at Linköping University, Sweden. Printed by LiU-Tryck 2018 © Dunyong Deng AbstractAdditive manufacturing (AM), also known as 3D printing, has gained significant interest in aerospace, energy, automotive and medical industries due to its capabilities of manufacturing components that are either prohibitively costly or impossible to manufacture by conventional processes. Among the various additive manufacturing processes for metallic components, electron beam melting (EBM) and selective laser melting (SLM) are two of the most widely used powder bed based processes, and have shown great potential for manufacturing high-end critical components, such as turbine blades and customized medical implants. The futures of the EBM and SLM are doubtlessly promising, but to fully realize their potentials there are still many challenges to overcome.Inconel 718 (IN718) is a nickel-base superalloy and has impressive combination of good mechanical properties and low cost. Though IN718 is being mostly used as a turbine disk material now, the initial introduction of IN718 was to overcome the poor weldability of superalloys in 1960s, since sluggish precipitation of strengthening phases γ ′ /γ ′′ enables good resistance to strain-age cracking during welding or post weld heat treatment. Given the similarity between AM and welding processes, IN718 has been widely applied to the metallic AM field to facilitate the understandings of process-microstructure-property relationships.The work presented in this licentiate thesis aims to better understand microstructures and mechanical properties EBM and SLM IN718, which have not been systematically investigated. Microstructures of EBM and SLM IN718 have been characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and correlated with the process conditions. Monotonic mechanical properties (e.g., Vickers microhardness and tensile properties) have also been measured and rationalized with regards to the microstructure evolutions before and after heat treatments.For EBM IN718, the results show the microstructure is not homogeneous but dependant on the location in the components, and the anisotropic mechanical properties are probably attributed to alignment of porosities rather than texture.iii Post heat treatment can slightly increase the mechanical strength compared to the as-manufactured condition but does not alter the anisotropy. SLM IN718 shows significantly different microstructure and mechanical properties to EBM IN718. The as-manufactured SLM IN718 has very fine dendritic microstructure and Laves phases in the interdendrites, and is "work-hardened" by the residual strains and dislocations present in the material. Mechanical properties are different between horizontally and vertically built samples, and heat treatment can m...

show abstract

Section: Materials Manufactured With Slmmentioning

confidence: 99%

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Deng

2018

Linköping Studies in Science and Technology. Licentiate Thesis

View full text Add to dashboard Cite

show abstract

“…The formed ball becomes isolated from the rest of the powder by comparatively large pores Tolochko et al, 2004). For low energy input, successive scan tracks do not fuse and large pores appear along the scan lines Li et al, 2010). Two kinds of pores are found in EBM parts.…”

Section: Mechanical Properties Of Slm-and Ebm-produced Ti-6al-4vmentioning

confidence: 99%

Generation and detection of defects in metallic parts fabricated by selective laser melting and electron beam melting and their effects on mechanical properties.

Gong¹

View full text Add to dashboard Cite

Gong, Haijun, "Generation and detection of defects in metallic parts fabricated by selective laser melting and electron beam melting and their effects on mechanical properties." (2013 Melting (EBM) are two common powder bed fusion processes within AM for fabricating metallic parts. In order to give designers and engineers more insights into employing AM, the quality and long-term behavior of SLM-and EBM-produced parts need to be carefully investigated. Thus, this research project aims to understand how processing parameters affect defect generation and distribution during SLM and EBM processes, to study the morphological features of defects, to identify effective non-destructive method(s) to detect these defects, and to characterize the effect of defects on mechanical properties of SLMand EBM-produced parts.The study began by generating stochastic defects via adjustment to process parameters from optimal parameters to marginal parameters, in order to correlate the vi porosity to the marginal parameters. Archimedes method was employed to estimate porosity of SLM-and EBM-produced specimens. After this, by using destructive characterization techniques, the defective specimens were sectioned. The morphology of stochastic defects was investigated based on their contour features on the cross sections.Micro CT was primarily used to evaluate the stochastic defects in the SLM and EBM parts and demonstrate their morphological characteristics and porosity in the single slices and reconstructed models. Finally, tensile and fatigue tests were carried out on Ti-6Al-4V parts with identified porosity. The fracture mechanism was analyzed.This study established a fundamental understanding of defects in parts made by SLM and EBM processes. Porosity was quantitatively correlated to the marginal parameters of SLM and EBM processes. Defects were differentiated based on their morphological properties and features. Micro CT was confirmed to be an effective nondestructive method for evaluating stochastic defects in SLM-and EBM-produced parts.The effects of stochastic defects on Ti-6Al-4V parts were determined based on tensile and fatigue tests. It was found that both microstructure and porosity have an impact on the mechanical properties of SLM-and EBM-produced parts.vii

show abstract

“…In this research a LENS 450 system is used to produce samples of 316L stainless steel and the effect of the subsequent layer addition on previous layers is investigated. 316L is an austenitic stainless steel that is commonly used for AM and is thus used in this research (Zhang et al, 2003) (Trelewicz et al, 2016) (Li et al, 2010). Austenitic stainless steels are of particular interest for direct laser deposition as they are relatively expensive to machine and have many potential uses (de Lima et al, 2014).…”

Section: Topicmentioning

confidence: 99%

“… Quick production time (Nakano et al, 2015)  Reduced number of production steps, near net shape process (Zietala et al, 2016)(Nakono et al, 2015  No tooling needed, reducing time and cost (Holmström, 2010)  Customisation (Holmström, 2010)  Ability to easily make changes to design (Holmström, 2010)  Production of complex parts (Uriondo et al, 2015)  Can produce parts with complex internal structures (Nakano et al, 2015)  Ability to produce both solid and porous structures (Li et al, 2010)  Repair of parts (Uriondo et al, 2015)  Small production batches are feasible and economical (Holmström, 2010)  Reduction of waste (Holmström, 2010)  A high percentage of the material can be recycled (Nakano et al, 2015)  New design possibilities, including multi-material parts (Shapiro et al, 2016) These benefits of AM drive the interest in research and development of AM technologies.…”

Section: Benefits Of Ammentioning

confidence: 99%

See 1 more Smart Citation

Investigation into the effect of subsequent layer addition on the microstructure and properties of previous layers during direct laser deposition of 316L stainless steel

Robinson¹

View full text Add to dashboard Cite

Additive manufacturing (AM) is a new and emerging technology in which further research is needed in order to make the most of its potential and unique benefits compared to conventional manufacturing. This current work helps to develop an understanding of AM processes by investigating the effect of subsequent layer addition on previous layers during direct laser deposition. As subsequent layers are added to a part, heat is transferred into previous layers, which may change the microstructure and properties of the pervious layers.There is no current research into the effect of these reheating cycles. In this work a new and innovative approach is used in which samples of different numbers of layers are produced and analysed, allowing the effect of reheating due to subsequent layer addition to be individually investigated. A LENS 450 system is used to produce samples of various numbers of layers (2 layer, 3 layer, 4 layer etc.) and the microstructure and hardness of the same layer in different samples is compared. Before the main research was performed the processing parameters were optimised for the LENS 450 system. It was determined that a powder feed rate of 5rpm, scanning speed of 18ipm and laser power of 300W produced the best component for this system, with a minimum amount of porosity. The optimum sample had only 0.34% porosity and a hardness of 203HV ± 23HV. The overall outcome of the work was that a generation of new knowledge about direct laser deposition processes was obtained, which will thus help in future development and control of AM processes. It was concluded that there was no significant change in properties with the subsequent layer addition due to the austenitic stainless steel exhibiting no phase changes on heating or cooling, which is a property unique to the austenitic stainless steels. END ii Acknowledgement

show abstract

316L Stainless Steel with Gradient Porosity Fabricated by Selective Laser Melting

Cited by 208 publications

References 14 publications

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Generation and detection of defects in metallic parts fabricated by selective laser melting and electron beam melting and their effects on mechanical properties.

Investigation into the effect of subsequent layer addition on the microstructure and properties of previous layers during direct laser deposition of 316L stainless steel

Contact Info

Product

Resources

About