Study on Misalignment of Focus Position in Laser Metal Deposition Shaping Processing

In order to investigate the effect on manufacturing quality of focus position misalignment between laser beam and powder convergence in laser metal deposition shaping (LMDS) processing, several experiments including single-track monolayer, straight thin-wall and ring thin-wall were made. The measurements and analysis on shape, size and surface quality of the experiment parts were carried out. An omnidirectional detecting method to check the misalignment of focus position was brought forward and tested. The results indicate that the misalignment of focus position directly affects the quality of shaping parts and shows the regularity, the detecting method can easily detect the focus position misalignment on random direction and angle and guide the adjustment on them.

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.813.191 ◽

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.

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Effect of heat accumulation on the single track formation during laser metal deposition and development of a framework for analyzing new process strategies

Journal of Laser Applications ◽

10.2351/7.0000307 ◽

2021 ◽

Vol 33 (1) ◽

pp. 012003

Author(s):

Markus Heilemann ◽

Vishnuu Jothi Prakash ◽

Lorenz Beulting ◽

Claus Emmelmann

Keyword(s):

Metal Deposition ◽

Laser Metal Deposition ◽

Single Track ◽

Heat Accumulation ◽

Track Formation ◽

New Process

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Laser Metal Deposition of Fe- and Co-Based Shape-Memory Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1161.105 ◽

2021 ◽

Vol 1161 ◽

pp. 105-112

Author(s):

Niklas Sommer ◽

Gabriel Mienert ◽

Malte Vollmer ◽

Christian Lauhoff ◽

Philipp Krooß ◽

...

Keyword(s):

Shape Memory Alloys ◽

Shape Memory ◽

Microstructural Evolution ◽

Microstructural Analysis ◽

Metal Deposition ◽

Thin Wall ◽

Laser Metal Deposition ◽

Wall Structures ◽

Iron Based ◽

First Time

In the present study, Iron-based FeMnAlNi and Cobalt-based CoNiGa shape-memory alloys (SMA) were processed by laser metal deposition for the first time. The materials show susceptibility to cracking upon processing when unheated substrates are employed. Pre-heating of the substrate materials eliminated cracking completely and enabled robust deposition of thin-wall structures. Microstructural analysis using optical microscopy revealed different microstructural evolution for the two materials considered.

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Prediction and validation of residual stresses generated during laser metal deposition of γ titanium aluminide thin wall structures

Materials Research Express ◽

10.1088/2053-1591/ab38ee ◽

2019 ◽

Vol 6 (10) ◽

pp. 106550 ◽

Cited By ~ 3

Author(s):

Mallikarjuna Balichakra ◽

Srikanth Bontha ◽

Prasad Krishna ◽

Vamsi Krishna Balla

Keyword(s):

Residual Stresses ◽

Titanium Aluminide ◽

Metal Deposition ◽

Thin Wall ◽

Laser Metal Deposition ◽

Wall Structures

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Effect of process parameters on formability and surface quality of selective laser melted Al-Zn-Sc-Zr alloy from single track to block specimen

Optics & Laser Technology ◽

10.1016/j.optlastec.2019.05.008 ◽

2019 ◽

Vol 118 ◽

pp. 132-139 ◽

Cited By ~ 8

Author(s):

Jiang Bi ◽

Zhenglong Lei ◽

Yanbin Chen ◽

Xi Chen ◽

Xikun Qin ◽

...

Keyword(s):

Surface Quality ◽

Process Parameters ◽

Single Track ◽

Zr Alloy

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Evaluation of the quality of layers applied by LDT laser metal deposition

AUTOBUSY – Technika Eksploatacja Systemy Transportowe ◽

10.24136/atest.2018.140 ◽

2018 ◽

Vol 19 (6) ◽

pp. 591-596

Author(s):

Andrzej Mazurkiewicz ◽

Andrzej Poprzeczka

Keyword(s):

Heat Affected Zone ◽

Heat Dissipation ◽

Scanning Speed ◽

Processing Parameters ◽

Metal Deposition ◽

Laser Metal Deposition ◽

Cross Sectional ◽

Weld Overlay ◽

The Cross

The article presents the results of a study of C45 carbon steel hardfacing using laser metal deposition with Stellit Co-21 powder. The microstructure of the cross-section of samples prepared with different scanning speed and the amount of used powder at constant laser power was observed. Analyzing the cross-sectional areas of the samples, it was found that, at specific production parameters, cracks occur in weld overlay, which should be associated with the amount of heat supplied and discharged, especially at the unheated basis.This may be confirmed by the presence of deposits of weakly branched dendrites in the microstructure, which should be related to the directional heat dissipation process and rapid directional crystallization. It is possible to regulate these phenomena by selecting appropriate processing parameters. The microstructure analysis of cross-sectional areas of samples after hardfacing using LDT technique indicates good metallurgical quality of the deposit with a small heat affected zone of about 660÷760m. The microhardness measurements on the sample cross-sections indicated a wide micohardness distribution ranging from 510HV1 in the weld overlay, about 410HV1 in the heat affected zone, to 270HV1 in the C45 steel base.

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Effect of Powder Feeding Rate on the Forming Quality of Alloy by Laser Melting Deposition

Journal of Physics Conference Series ◽

10.1088/1742-6596/2083/2/022024 ◽

2021 ◽

Vol 2083 (2) ◽

pp. 022024

Author(s):

Chenghong Duan ◽

Yinzhou Zhang ◽

Xiangpeng Luo

Keyword(s):

Surface Quality ◽

Feeding Rate ◽

Granular Bainite ◽

Single Track ◽

Laser Melting ◽

Forming Quality ◽

Metallurgical Bonding ◽

Laser Melting Deposition ◽

Powder Feeding

Abstract 12CrNi2 alloy steel was prepared by Laser Melting Deposition (LMD) technology, and the effect of powder feeding rate on surface quality, internal defects, microstructure, and microhardness of the single track and manufactured part were investigated. The results show that the metallurgical bonding of the single track deteriorates, the surface quality of the manufactured part is improved, the average microhardness of the manufactured part increases, and the number of pores first decreases and then increases with the increase of powder feeding rate. At the lower powder feeding rate, the manufactured parts have larger pore defects, while at the higher powder feeding rate, the manufactured parts have poor fusion defects. The main phase composition of the manufactured parts is ferrite(F), granular bainite (GB), and pearlite(P), and the manufactured part has finer grains at the higher powder feeding rate.

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Analysis on surface finish of thin-wall parts by laser metal deposition with annular beam

Optics & Laser Technology ◽

10.1016/j.optlastec.2019.105605 ◽

2019 ◽

Vol 119 ◽

pp. 105605 ◽

Cited By ~ 3

Author(s):

Jinchao Zhang ◽

Shihong Shi ◽

Geyan Fu ◽

Jianjun Shi ◽

Gangxian Zhu ◽

...

Keyword(s):

Surface Finish ◽

Metal Deposition ◽

Thin Wall ◽

Laser Metal Deposition ◽

Annular Beam

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Influence of laser parameters and Ti content on the surface morphology of L-PBF fabricated Titania

Rapid Prototyping Journal ◽

10.1108/rpj-03-2020-0050 ◽

2020 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Abid Ullah ◽

HengAn Wu ◽

Asif Ur Rehman ◽

YinBo Zhu ◽

Tingting Liu ◽

...

Keyword(s):

Surface Morphology ◽

Laser Beam ◽

Surface Quality ◽

Selective Oxidation ◽

Laser Power ◽

Scanning Speed ◽

Content Type ◽

Powder Bed ◽

Laser Parameters

Purpose The purpose of this paper is to eliminate Part defects and enrich additive manufacturing of ceramics. Laser powder bed fusion (L-PBF) experiments were carried to investigate the effects of laser parameters and selective oxidation of Titanium (mixed with TiO2) on the microstructure, surface quality and melting state of Titania. The causes of several L-PBF parts defects were thoroughly analyzed. Design/methodology/approach Laser power and scanning speed were varied within a specific range (50–125 W and 170–200 mm/s, respectively). Furthermore, varying loads of Ti (1%, 3%, 5% and 15%) were mixed with TiO2, which was selectively oxidized with laser beam in the presence of oxygen environment. Findings Part defects such as cracks, pores and uneven grains growth were widely reduced in TiO2 L-PBF specimens. Increasing the laser power and decreasing the scanning speed shown significant improvements in the surface morphology of TiO2 ceramics. The amount of Ti material was fully melted and simultaneously changed into TiO2 by the application of the laser beam. The selective oxidation of Ti material also improved the melting condition, microstructure and surface quality of the specimens. Originality/value TiO2 ceramic specimens were produced through L-PBF process. Increasing the laser power and decreasing the scanning speed is an effective way to sufficiently melt the powders and reduce parts defects. Selective oxidation of Ti by a high power laser beam approach was used to improve the manufacturability of TiO2 specimens.

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