scholarly journals Modification of Structural Properties Using Process Parameters and Surface Treatment of Monolithic and Thin-Walled Parts Obtained by Selective Laser Melting

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5662
Author(s):  
Krzysztof Grzelak ◽  
Janusz Kluczyński ◽  
Ireneusz Szachogłuchowicz ◽  
Jakub Łuszczek ◽  
Lucjan Śnieżek ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Energy Density ◽  
Surface Treatment ◽  
Process Parameters ◽  
Positive Influence ◽  
Porosity Reduction ◽  
Density Growth ◽  
Parameter Modification ◽  
Thin Walled ◽  
Roughness Measurements

Additive manufacturing is one of the most popular technological processes and is being considered in many research works, a lot of which are related to thin-walled parts analysis. There are many cases where different part geometries were manufactured using the same process parameters. That kind of approach often causes different porosity and surface roughness values in the geometry of each produced part. In this work, the porosity of thin-walled and monolithic parts was compared. To analyze additively manufactured samples, porosity and microstructural analyses were done. Additionally, to check the influence of process parameter modification on the manufactured parts’ properties, hardness and roughness measurements were made. Surface roughness and the influence of surface treatment were also taken into account. Porosity reduction of thin-walled parts with energy density growth was observed. Additionally, a positive influence of slight energy density growth on the surface roughness of produced parts was registered. Comparing two extreme-parameter groups, it was observed that a 56% energy density increase caused an almost 85% decrease in porosity and a 45% increase in surface roughness. Additional surface treatment of the material allowed for a 70–90% roughness reduction.

scholarly journals On the Relevance of Volumetric Energy Density in the Investigation of Inconel 718 Laser Powder Bed Fusion

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 538 ◽  
Author(s):  
Fabrizia Caiazzo ◽  
Vittorio Alfieri ◽  
Giuseppe Casalino
Keyword(s):  
Surface Roughness ◽  
Energy Density ◽  
Process Parameters ◽  
Vickers Hardness ◽  
Powder Bed Fusion ◽  
Processing Conditions ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Fractional Density ◽  
Experimental Variation

Laser powder bed fusion (LPBF) can fabricate products with tailored mechanical and surface properties. In fact, surface texture, roughness, pore size, the resulting fractional density, and microhardness highly depend on the processing conditions, which are very difficult to deal with. Therefore, this paper aims at investigating the relevance of the volumetric energy density (VED) that is a concise index of some governing factors with a potential operational use. This paper proves the fact that the observed experimental variation in the surface roughness, number and size of pores, the fractional density, and Vickers hardness can be explained in terms of VED that can help the investigator in dealing with several process parameters at once.

In-Process Laser Re-Melting of Thin Walled Parts to Improve Surface Quality after Laser Metal Deposition

2019 ◽  
Vol 813 ◽  
pp. 191-196
Author(s):  
Francesco Bruzzo ◽  
Guendalina Catalano ◽  
Ali Gökhan Demir ◽  
Barbara Previtali
Keyword(s):  
Surface Roughness ◽  
Energy Density ◽  
Surface Quality ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Average Roughness ◽  
Thin Walls ◽  
Energy Inputs ◽  
Thin Walled

Laser metal deposition (LMD) is an additive manufacturing process highly adaptable to medium to large sized components with bulky structures as well as thin walls. Low surface quality of as-deposited LMD manufactured components with average roughness values (Ra) around 15-20μm is one of the main drawbacks that prevent the use of the part without the implementation of costly and time-consuming post-processes. In this work laser re-melting is applied right after LMD process with the use of the same equipment used for the deposition to treat AISI 316L thin walled parts. The surface quality improvement is assessed through the measurement of both areal surface roughness Sa(0.8mm) QUOTE and waviness Wa QUOTE (0.8mm) parameters. Moreover, roughness power spectrum is used to point out the presence of principal periodical components both in the as-deposited and in the re-melted surfaces. Then, the transfer function is calculated to better understand the effects of laser re-melting on the topography evolution, measuring the changes of individual components contributing to the surface roughness such as the layering technique and the presence of sintered particles. Experiments showed that while low energy density inputs are not capable to properly modify the additive surface topography, excessive energy inputs impose a strong periodical component with wavelength equal to the laser scan spacing and directionality determined by the used strategy. When a proper amount of energy density input is used, laser re-melting is capable to generate smooth isotropic topographies without visible periodical surface structures.

Development of Centreless Electric Discharge Grinding Machining Process and Optimization of Process Parameters

2020 ◽  
Vol 14 ◽  
Author(s):  
MS Shekhawat ◽  
Harlal Singh Mali ◽  
APS Rathore
Keyword(s):  
Surface Roughness ◽  
Process Parameters ◽  
Electric Discharge ◽  
Duty Cycle ◽  
Average Surface Roughness ◽  
Peak Current ◽  
Average Surface ◽  
Inconel 600 ◽  
Thin Walled ◽  
Pulse On Time

Aims & Objective: Producing thin walled rotationally symmetrical parts of difficult-to-machine materials by electrical discharge machining is an evolving field of research. Poor heat transmissivity, high hot strength and in-process deflection of thin walled Inconel 600 parts puts great challenge for its processing by conventional machining methods. Methods: In this study a novel hybrid process called centreless electric discharge grinding(CEDG) is employed for machining of Inconel 600 tubes using rotating disc wheel electrode to improve process parameters. This paper details about the experimental findings of the influence of four process parameters viz. pulse on time, peak current, gap voltage, and duty cycle on the responses viz. average material removal rate (MRR) and average surface roughness(Ra). Response surface method’s (RSM) central composite design was implemented to determine the effects of parameters on responses. Analysis of variance (ANOVA) techniques were employed to establish the adequacy of the mathematical models and to analyse the significance of regression coefficients. RSM’s desirability approach was used to solve the multi-response optimization. Results: It was clearly noticed that the peak current and gap voltage were the most influential parameters to affect the MRR and surface roughness. Maximum average MRR of 473 mg per min. was achieved at pulse on time 60µs, peak current 25 amps, gap voltage 40 V, at duty cycle of 8 while minimum average surface roughness of 8.4 µm Ra was obtained at pulse on time 40µs, peak current 15 amps, gap voltage 40 V, and duty cycle 6. Conclusion: Confirmation run was conducted by adjusting the variables at optimal level within the selected range. It was concluded that optimum level of variables can be determined for optimized responses prior to conduct of experiment.

scholarly journals Effect of Process Parameter Modification and Hot Isostatic Pressing on the Mechanical Properties of Selectively Laser-Melted 316L Steel

2020 ◽  
Author(s):  
Janusz Kluczynski ◽  
Lucjan Śnieżek ◽  
Krzysztof Grzelak ◽  
Artur Oziębło ◽  
Krzysztof Perkowski ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Density ◽  
Process Parameters ◽  
Hot Isostatic Pressing ◽  
Tensile Tests ◽  
Image Correlation ◽  
Deformation Analysis ◽  
Material Strength ◽  
Isostatic Pressing ◽  
Parameter Modification

Industries that rely on additive manufacturing of metallic elements, especially biomedical companies, require material science-based knowledge of how process parameters and methods affect element properties, but such phenomena are incompletely understood. In this study, we investigated the influence of selective laser melting (SLM) process parameters and additional heat treatment on mechanical properties. The research included structural analysis of residual stress, microstructure, and scleronomic hardness in low-depth measurements. Tensile tests with element deformation analysis using digital image correlation (DIC) were performed as well. Experiment results showed it was possible to observe the porosity growth mechanism and its influence on material strength. Elements manufactured with 20% lower energy density had almost half the elongation, which was directly connected with porosity growth during energy density reduction. Hot isostatic pressing (HIP) treatment allowed for a significant reduction of porosity and helped achieve properties similar to elements manufactured using different levels of energy density.

scholarly journals Application of Additive Technology in Precision Casting

2020 ◽  
Vol 5 (2) ◽  
pp. 43-56
Author(s):  
Dávid Halápi ◽  
László Varga
Keyword(s):  
Surface Roughness ◽  
3D Printing ◽  
Light Microscopy ◽  
Ethyl Acetate ◽  
Surface Treatment ◽  
Additive Technology ◽  
Microscopic Images ◽  
Precision Casting ◽  
Measurement Series ◽  
Roughness Measurements

In this paper the surface of the prepared test specimens had been examined with light microscopy and surface roughness measurements. In order to improve the surface smoothness of PLA specimens, application of ethyl acetate was required. After this surface treatment, microscopic images were taken again. The melting and decomposition temperatures of the materials had been determined using derivatography. The chosen method was precision casting with gypsum molding. Also, the plaster molds had been burnt out according to the predefined melting and firing diagram. The measurement series shows that the samples produced by 3D printing can also be used in the field of precision casting. They provide greater freedom of design, more sophisticated pieces, and prototypes can be finished in a shorter amount of time.

Surface roughness measurements of vanadium-contaminated fluidized cracking catalysts by atomic force microscopy

1996 ◽  
Vol 54 ◽  
pp. 866-867
Author(s):  
H. Kinney ◽  
M.L. Occelli ◽  
S.A.C. Gould
Keyword(s):  
Surface Roughness ◽  
Zeolite Y ◽  
Atomic Level ◽  
Microporous Structure ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Roughness Measurements ◽  
Cracking Catalysts

For this study we have used a contact mode atomic force microscope (AFM) to study to topography of fluidized cracking catalysts (FCC), before and after contamination with 5% vanadium. We selected the AFM because of its ability to well characterize the surface roughness of materials down to the atomic level. It is believed that the cracking in the FCCs occurs mainly on the catalysts top 10-15 μm suggesting that the surface corrugation could play a key role in the FCCs microactivity properties. To test this hypothesis, we chose vanadium as a contaminate because this metal is capable of irreversibly destroying the FCC crystallinity as well as it microporous structure. In addition, we wanted to examine the extent to which steaming affects the vanadium contaminated FCC. Using the AFM, we measured the surface roughness of FCCs, before and after contamination and after steaming.We obtained our FCC (GRZ-1) from Davison. The FCC is generated so that it contains and estimated 35% rare earth exchaged zeolite Y, 50% kaolin and 15% binder.

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