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

Abstract The control of the track shape in laser metal deposition technology by the QCW laser mode has been studied. The different geometric characteristics of the tracks are shown to obtain at the same average laser power, depending on the selected laser power control mode. The difference in the temperature regimes of track formation is shown.

Download Full-text

Fabrication of Metal Matrix Composite by Laser Metal Deposition—A New Process Approach by Direct Dry Injection of Nanopowders

Materials ◽

10.3390/ma12213584 ◽

2019 ◽

Vol 12 (21) ◽

pp. 3584 ◽

Cited By ~ 2

Author(s):

Briac Lanfant ◽

Florian Bär ◽

Antaryami Mohanta ◽

Marc Leparoux

Keyword(s):

Metal Matrix ◽

Metallic Matrix ◽

Process Approach ◽

Metal Deposition ◽

Al2o3 Nanoparticles ◽

Laser Metal Deposition ◽

Metal Matrix Nanocomposites ◽

X Ray ◽

New Process

Laser Metal Deposition (LMD) offers new perspectives for the fabrication of metal matrix nanocomposites (MMnCs). Current methods to produce MMnCs by LMD systematically involve the premixing of the nanopowders and the micropowders or require in-situ strategies, thereby restricting the possibilities to adjust the nature, content and location of the nano-reinforcement during printing. The objective of this study is to overcome such restrictions and propose a new process approach by direct injection of nanoparticles into a metallic matrix. Alumina (n-Al2O3) nanoparticles were introduced into a titanium matrix by using two different direct dry injection modes in order to locally increase the hardness. Energy dispersive X-ray spectroscopy (EDS) analyses validate the successful incorporation of the n-Al2O3 at chosen locations. Optical and high resolution transmission electron microscopic (HR-TEM) observations as well as X-ray diffraction (XRD) analyses indicate that n-Al2O3 powders are partly or totally dissolved into the Ti melted pool leading to the in-situ formation of a composite consisting of fine α2 lamellar microstructure within a Ti matrix and a solid solution with oxygen. Mechanical tests show a significant increase in hardness with the increase of injected n-Al2O3 amount. A maximum of 620 HV was measured that is almost 4 times higher than the pure LMD-printed Ti structure.

Download Full-text

Observation of Vapor Plume Behavior and Process Stability at Single-Track and Multi-Track Levels in Laser Powder Bed Fusion Regime

Metals ◽

10.3390/met11060937 ◽

2021 ◽

Vol 11 (6) ◽

pp. 937

Author(s):

Hang Zheng ◽

You Wang ◽

Yinkai Xie ◽

Shengkun Yang ◽

Rui Hou ◽

...

Keyword(s):

High Speed ◽

Powder Bed Fusion ◽

Single Track ◽

Laser Powder Bed Fusion ◽

Process Stability ◽

Heat Accumulation ◽

Powder Bed ◽

Metal Parts ◽

Vapor Plume ◽

Track Formation

Laser powder bed fusion (LPBF) is a promising additive manufacturing technology for producing metal parts with complex geometric features. However, the issue concerning process stability and repeatability still hinders its future acceptance by the industry. Gaining a better understanding of the behavior and stability of the evaporation process is an important step towards further insights into the complex interaction between laser and material. In this study, we used off-axis high-speed camera to observe vapor plume evolution in single-track formation on bare Ti-6Al-4V plates; the results showed that evaporation has a strong effect on melting quality even if the keyhole is not developed. We then expanded the experiments to multi-track level and found that the melting mode can change as the result of heat accumulation. The results show the possibility that keyhole regime may be reached even if it starts with a combination of parameters below the threshold for keyhole formation in single-track-level observation.

Download Full-text

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

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.16-19.1218 ◽

2009 ◽

Vol 16-19 ◽

pp. 1218-1222

Author(s):

Feng Jie Tian ◽

Wei Jun Liu ◽

Xiao Feng Shang ◽

Guang Yang

Keyword(s):

Laser Beam ◽

Surface Quality ◽

Metal Deposition ◽

Thin Wall ◽

Focus Position ◽

Laser Metal Deposition ◽

Single Track ◽

Random Direction ◽

Detecting Method

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.

Download Full-text

Numerical and Experimental Investigations of Laser Metal Deposition (LMD) Using STS 316L

Applied Sciences ◽

10.3390/app10144874 ◽

2020 ◽

Vol 10 (14) ◽

pp. 4874

Author(s):

Jaewoong Park ◽

Jin-young Kim ◽

Inseo Ji ◽

Seung Hwan Lee

Keyword(s):

Numerical Study ◽

Deposition Process ◽

Metal Deposition ◽

Experimental Investigations ◽

Uniform Structure ◽

Laser Metal Deposition ◽

Heat Accumulation ◽

Multilayer Deposition ◽

Microstructure Morphology ◽

Solidification Parameters

This study aimed to understand the effect of heat accumulation on microstructure formation on STS 316L during multilayer deposition by a laser metal deposition (LMD) process and to predict the microstructure morphology. A comprehensive experimental and numerical study was conducted to quantify the solidification parameters (temperature gradient (G) and growth rate (R)) in the LMD multilayer deposition process. During deposition, the temperature profile at a fixed point in the deposit was measured to validate the numerical model, and then the solidification parameters were quantified using the model. Simultaneously, the microstructure of the deposit was investigated to confirm the microstructure morphology. Then, a relationship between the microstructure morphology and the G/R was proposed using a solidification map. The findings of this study can guide the design of scanning paths to produce deposits with a uniform structure.

Download Full-text