Geometrical feature analysis of Co-Cr-Mo single tracks after selective laser melting processing

2015 ◽  
Vol 21 (3) ◽  
pp. 287-300 ◽  
Author(s):  
Karla Monroy ◽  
Jordi Delgado ◽  
Lidia Sereno ◽  
Joaquim Ciurana ◽  
Nicolas J Hendrichs
Keyword(s):  
Selective Laser Melting ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Single Track ◽  
Cobalt Chromium ◽  
Laser Melting ◽  
Content Type ◽  
Dimensional Precision ◽  
Morphologic Characteristics ◽  
Definition Of

Purpose – Therefore, the purpose of this study is to understand the relationships between the processing parameters and the geometric form of the produced single tracks, in order to control dimensional quality in future experimentations. The quality of the deposited single track and layer is of prime importance in the selective laser melting (SLM) process, as it affects the product quality in terms of dimensional precision and product performance. Design/methodology/approach – In this paper, a vertical milling machining center equipped with an Ytterbium-fiber laser was used in the SLM experimentation to form single cobalt-chromium-molybdenum (CoCrMo) tracks. The different geometric features and the influence of the scanning parameters on these morphologic characteristics were studied statistically by means of ANOVA. Findings – Evidently, track height (h1) inaccuracy reduced in layer thicknesses between 100 and 200 μm. The re-melt depth (h2) was determined by the energy parameters, with laser power of 325-350 W and scanning speed (SS) of 66.6-83.3 mm/s being the most favorable parameters to obtain the required anchoring. Moreover, a contact angle of 117° was proposed as optimal, as it permitted an adequate overlapping region and a full densification, and, finally, an SS of 50 mm/s and a layer thickness of 250 were suggested for its development. Originality/value – The comprehension of the phenomena inherent to the process is related to the single track geometrical characteristics, which allow the definition of an optimal value for each factor for a further proposal of processing conditions that can finally derive a higher precision, wetting, density and mechanical properties.

Track evolution and surface characteristics of selective laser melting Ti6Al4V

2018 ◽  
Vol 24 (9) ◽  
pp. 1554-1562 ◽  
Author(s):  
Luo Zhang ◽  
Haihong Zhu ◽  
Jiahe Liu ◽  
Xiaoyan Zeng
Keyword(s):  
Surface Morphology ◽  
Selective Laser Melting ◽  
Surface Characteristics ◽  
Scanning Speed ◽  
Bulk Sample ◽  
Three Dimension ◽  
Single Track ◽  
Heat Accumulation ◽  
Laser Melting ◽  
Content Type

Purpose The purpose of this paper is to investigate the track evolution and surface characteristics of selective laser melting Ti6Al4V. Design/methodology/approach In the present paper, Ti6Al4V single-track, multi-track and bulk sample were formed at different scanning speed by selective laser melting (SLM). Then, the surface morphology, three-dimension profile and surface roughness were evaluated. The width of the single and multi-track was measured and compared. Findings The results showed that the heat accumulation played a great role on the evolution of tracks and surface characteristics from single-track to multi-track and to bulk. The surface morphology of the subsequent tracks became more regular when the single-track was irregular at the same high scanning speed. The width of last track Wn was always larger than that of the first track W1. The Ra of the top of the bulk increased with the increase of the scanning speed, this trend was as same as the Ra of the single-track, but the trend of Ra of the side was opposite. Originality/value The effect of heat accumulation on the track evolution and surface characteristics is obtained. The results can help to derive a smooth surface with a regular and continuous track in SLM.

Effect of processing parameters on forming defects during selective laser melting of AlSi10Mg powder

2020 ◽  
Vol 26 (5) ◽  
pp. 871-879 ◽  
Author(s):  
Haihua Wu ◽  
Junfeng Li ◽  
Zhengying Wei ◽  
Pei Wei
Keyword(s):  
Selective Laser Melting ◽  
Laser Power ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Argon Pressure ◽  
Powder Layer ◽  
Laser Melting ◽  
Content Type ◽  
Scan Speed ◽  
Forming Defects

Purpose To fabricate a selective laser melting (SLM)-processed AlSi10Mg part with almost full density and free of any apparent pores, this study aims to investigate the effect of ambient argon pressure and laser scanning speed on the particles splash during the AlSi10Mg powder bed laser melting. Design/methodology/approach Based on the discrete element method (DEM), a 3D model of random distribution of powder particles was established, and the 3D free surface of SLM forming process was dynamically tracked by the volume of fluid, where a Gaussian laser beam acts as the energy source melting the powder bed. Through the numerical simulation and process experimental research, the effect of the applied laser power and scanning speed on the operating laser melting temperature was studied. Findings The process stability has a fundamental role in the porosity formation, which is process-dependent. The effect of the processing conditions on the process stability and the resultant forming defects were clarified. Research limitations/implications The results shows that the pores were the main defects present in the SLM-processed AlSi10Mg sample, which decreases the densification level of the sample. Practical implications The optimal processing parameters (argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm ) applied during laser melting can improve the quality of selective laser melting of AlSi10Mg, Social implications It can provide a technological support for 3D printing. Originality/value Based on the analysis of the pore and balling formation mechanisms, the optimal processing parameters have been obtained, which were argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm. Then, a near-fully dense sample free of any apparent pores on the cross-sectional microstructure was produced by SLM, wherein the relative density of the as-built samples is larger than 97.5%.

Effect of scanning speed on the solidification process of Al2O3/GdAlO3/ZrO2 eutectic ceramics in a single track by selective laser melting

2019 ◽  
Vol 45 (14) ◽  
pp. 17252-17257
Author(s):  
Haifang Liu ◽  
Haijun Su ◽  
Zhonglin Shen ◽  
Di Zhao ◽  
Yuan Liu ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Solidification Process ◽  
Scanning Speed ◽  
Single Track ◽  
Laser Melting

Optimal Scanning Condition of Selective Laser Melting Processing with Stainless Steel 316L Powder

2011 ◽  
Vol 341-342 ◽  
pp. 816-820 ◽  
Author(s):  
Apinya Laohaprapanon ◽  
Pongnarin Jeamwatthanachai ◽  
Marut Wongcumchang ◽  
Nattapon Chantarapanich ◽  
Surapon Chantaweroad ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Selective Laser Melting ◽  
Visual Inspection ◽  
Processing Condition ◽  
Density Measurement ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Stainless Steel 316L ◽  
Laser Melting ◽  
Optimal Processing

This study aimed to investigate the stainless steel 316L processing by means of selective laser melting (SLM). The processing parameters under consideration included laser power (25-225 W), scanning speed (50-320 mm/s), and scan spacing (0.04 and 0.06 mm). Every processing was constrained the layer thickness as of 100 µm. All parameters were performed based on two experiments, line scanning and multiple layers scanning. Each of final workpieces was examined by visual inspection, density measurement, hardness, and built rate. From the experiments, the optimal processing conditions which produced the smooth tracks were obtained. The workpiece processed by this optimal processing condition presented quality characteristics with 97.6% density and 220±6 HV hardness.

scholarly journals Optimisation of selective laser melting parameters for the Ni-based superalloy IN-738 LC using Doehlert’s design

2017 ◽  
Vol 23 (5) ◽  
pp. 881-892 ◽  
Author(s):  
Nataliya Perevoshchikova ◽  
Jordan Rigaud ◽  
Yu Sha ◽  
Martin Heilmaier ◽  
Barrie Finnin ◽  
...  
Keyword(s):  
Image Analysis ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Processing Parameters ◽  
Powder Alloy ◽  
Operating Parameters ◽  
Laser Melting ◽  
Doehlert Design ◽  
Feasible Set ◽  
Content Type

Purpose The Ni-based superalloy IN-738 LC is known to be susceptible to porosity and different types of cracking during the build-up process and, thus, challenging to manufacture using selective laser melting (SLM). Determining a feasible set of operating parameters for SLM of nickel-based superalloys involves new approach to experimental design based on the Doehlert method that assists in determining an optimal (feasible) set of operating parameters for SLM of IN-738 LC powder alloy. Design/methodology/approach The SLM parameters are evaluated in terms of their effectiveness in obtaining the microstructure with a porosity content of <0.5 per cent and without micro-cracking. The experimental approach is exemplified with the Doehlert matrix response variable, relative density, by comparing Archimedes method with microstructural assessments of pores and cracks from image analysis. The effect of heat treatment (HT) and hot isostatic pressing (HIP) on the microstructure of the SLMed IN-738 LC powder alloy has been examined and the consequential tensile response characterised. Findings By using optimised process parameters (low heat input, medium scanning speed and small hatching distance) which provides medium energy density, samples of IN-738 LC with a macroscopic porosity <0.5 per cent and free of micro-cracks can be manufactured by SLM. The results indicate that HIP of SLMed material did not lead to a noticeable effect on mechanical properties compared to HT of SLMed material suggesting that the level of both porosity and crack density might be already below the detection limit for the mere heat-treated material. Originality/value SLM processing parameters (power, scan speed, hatching distance) for IN-738 LC were successfully optimised after only 14 experiments using Doehlert design. Two independent methods, Archimedes method and image analysis, were used in this study to assess relative density of SLM-produced samples with sets of processing parameters showing coherency in prediction with predicted response by Doehlert design.

scholarly journals Collaborative Optimization on Density and Surface Roughness of 316L Stainless Steel in Selective Laser Melting

2020 ◽  
Author(s):  
Yong Deng ◽  
Zhongfa Mao ◽  
Nan Yang ◽  
Xiaodong Niu ◽  
Xiangdong Lu
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Laser Power ◽  
316L Stainless Steel ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Collaborative Optimization ◽  
Laser Melting

Although the concept of additive manufacturing has been proposed for several decades, momentum of selective laser melting (SLM) is finally starting to build. In SLM, density and surface roughness, as the important quality indexes of SLMed parts, are dependent on the processing parameters. However, there are few studies on their collaborative optimization in SLM to obtain high relative density and low surface roughness simultaneously in the previous literature. In this work, the response surface method was adopted to study the influences of different processing parameters (laser power, scanning speed and hatch space) on density and surface roughness of 316L stainless steel parts fabricated by SLM. The statistical relationship model between processing parameters and manufacturing quality is established. A multi-objective collaborative optimization strategy considering both density and surface roughness is proposed. The experimental results show that the main effects of processing parameters on the density and surface roughness are similar. It is noted that the effects of the laser power and scanning speed on the above objective quality show highly significant, while hatch space behaves an insignificant impact. Based on the above optimization, 316L stainless steel parts with excellent surface roughness and relative density can be obtained by SLM with optimized processing parameters.

Effects of the Processing Parameters on the Forming Quality of Stainless Steel Parts by Selective Laser Melting

2011 ◽  
Vol 189-193 ◽  
pp. 3668-3671 ◽  
Author(s):  
Qing Song Wei ◽  
Xiao Zhao ◽  
Li Wang ◽  
Rui Di Li ◽  
Jie Liu ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Selective Laser Melting ◽  
Molten Pool ◽  
Laser Power ◽  
Single Layer ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Powder Layer ◽  
Laser Melting

Selective Laser Melting (SLM) can produce high-performance metal parts with complex structures. However, it’s difficult to control the processing parameters, because many factors involves. From the perspective of the molten pool, the study focuses on the effects of processing parameters, including scanning speed, laser power, scanning space, layer thickness, and scanning strategies, on the surface quality, the balling effect, the density of SLM parts, by conducting experiments of single track, single layer and block forming. The results show that the quality of the molten pool is affected by laser power and scanning speed. Scanning drove in the strategy of “jumping and turning”，a smooth surface and a less balling effect will be obtained. The thicker the powder layer is, the lower density will be obtained. The optimal parameters from series of experiments are: laser power of 98W; scanning speed of 90mm/s; scanning space of 0.07mm; layer thickness of 0.1mm; and scanning strategy of “jumping and turning”.

The influence of a process interruption on tensile properties of AlSi10Mg samples produced by selective laser melting

2019 ◽  
Vol 25 (8) ◽  
pp. 1442-1452 ◽  
Author(s):  
Vincent Hammond ◽  
Michael Schuch ◽  
Matthias Bleckmann
Keyword(s):  
Tensile Properties ◽  
Selective Laser Melting ◽  
Continuous Process ◽  
Processing Parameters ◽  
Laser Melting ◽  
Content Type ◽  
Random Failure ◽  
Pressure Die Casting ◽  
Suitable Technique ◽  
Cylindrical Samples

Purpose The purpose of this paper is to investigate the influence of a process interruption on the tensile properties of AlSi10Mg samples produced by selective laser melting (SLM). Design/methodology/approach Using identical processing parameters, cylindrical samples were produced in either a continuous or interrupted SLM build operation. The tensile properties and microstructure of the samples were determined as a function of process type as well as orientation. Findings All samples produced in this paper displayed superior tensile properties to those produced in high pressure die casting. In general, the samples produced in the continuous build process had higher strengths and microhardness than those produced in the interrupted process. However, while most samples displayed random failure locations, the vertical samples produced in the interrupted build process showed a strong tendency for localized failure in the vicinity of the stoppage plane. Originality/value This paper demonstrated that samples produced in an interrupted build process tend to have poorer mechanical properties than those produced in a continuous process. Together, these observations highlight the importance of a suitable technique for restarting and completing an interrupted build process to ensure the production of high quality components.

A Study of Keyhole Porosity in Selective Laser Melting: Single-Track Scanning With Micro-CT Analysis

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Subin Shrestha ◽  
Thomas Starr ◽  
Kevin Chou
Keyword(s):  
Selective Laser Melting ◽  
Laser Power ◽  
Scanning Speed ◽  
Single Track ◽  
Micro Computed Tomography ◽  
Laser Melting ◽  
Pore Characteristics ◽  
Line Energy ◽  
The Individual ◽  
Pore Number

Porosity is an inherent attribute in selective laser melting (SLM) and profoundly degrades the build part quality and its performance. This study attempts to understand and characterize the keyhole pores formed during single-track scanning in SLM. First, 24 single tracks were generated using different line energy density (LED) levels, ranging from 0.1 J/mm to 0.98 J/mm, by varying the laser power and the scanning speed. The samples were then scanned by micro-computed tomography to measure keyhole pores and analyze the pore characteristics. The results show a general trend that the severity of the keyhole porosity increases with the increase of the LED with exceptions of certain patterns, implying important individual contributions from the parameters. Next, by keeping the LED constant in another set of experiments, different combinations of the power and the speed were tested to investigate the individual effect. Based on the results obtained, the laser power appears to have a greater effect than the scanning speed on both the pore number and the pore volume as well as the pore depth. For the same LED, the pore number and volume increase with increasing laser power until a certain critical level, beyond which, both the pore number and volume will decrease, if the power is further increased. For the LED of 0.32 J/mm, 0.4 J/mm, and 0.48 J/mm, the critical laser power that reverses the trend is about 132 W, 140 W, and 144 W, respectively.

Experimental Investigation into the Single-Track of Selective Laser Melting of IN625

2011 ◽  
Vol 233-235 ◽  
pp. 2844-2848 ◽  
Author(s):  
Li Wang ◽  
Qing Song Wei ◽  
Yu Sheng Shi ◽  
Jin Hui Liu ◽  
Wen Ting He
Keyword(s):  
Energy Density ◽  
Relative Density ◽  
Surface Quality ◽  
Selective Laser Melting ◽  
Laser Power ◽  
Laser Energy ◽  
Scanning Speed ◽  
Single Track ◽  
Laser Melting ◽  
Metallic Parts

Selective laser melting(SLM) is driven by the need to fabricate functional metallic parts and tools with near shape and density. The method of process to fabricate a metal part will save materials, time and energy compared to the traditional manufacturing methods. Unlike the selective laser sintering (SLS), the metal powder particles are molten by the laser beam during the process of selective laser melting. In this paper, IN625 powders were adopted to investigate the characters of single molten track. The factors that affect the surface quality and relative density are the process parameters such as the laser energy, scan speed and so on. They were studied to find out the correlation between the parameters and formation of single-track. It has been found that Optimal ratio between laser power and scanning speed (P/v) is 1-1.5 for IN625 SLM. P/v is the linear energy density. It also has been found that the width and height of single-track can be calculated when the linear energy density is given. In this study the laser power, scan spacing and the hatch spacing which affect the surface quality and the relative density of the metallic parts were optimized.

Sign in / Sign up

Export Citation Format

Share Document