3D-imaging of selective laser melting defects in a Co–Cr–Mo alloy by synchrotron radiation micro-CT

Zhou, Xin; Wang, Dianzheng; Liu, Xihe; Zhang, Dandan; Qu, S.; Ma, Jing; London, Gary; Shen, Zhijian; Liu, Wei

doi:10.1016/j.actamat.2015.07.014

Cited by 176 publications

(50 citation statements)

References 44 publications

(72 reference statements)

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“…The rough surface directly contributes to the poor flow of the molten metal to form interlayer defects. The interlayer defects may gradually extend and propagate upwards to form large multi-layer defects in a continuous deposition process [38].…”

Section: Incomplete Fusion Holesmentioning

confidence: 99%

Defect Formation Mechanisms in Selective Laser Melting: A Review

Zhang

Bai

2017

Chin. J. Mech. Eng.

700

269

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Defect formation is a common problem in selective laser melting (SLM). This paper provides a review of defect formation mechanisms in SLM. It summarizes the recent research outcomes on defect findings and classification, analyzes formation mechanisms of the common defects, such as porosities, incomplete fusion holes, and cracks. The paper discusses the effect of the process parameters on defect formation and the impact of defect formation on the mechanical properties of a fabricated part. Based on the discussion, the paper proposes strategies for defect suppression and control in SLM.

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Section: Incomplete Fusion Holesmentioning

confidence: 99%

Defect Formation Mechanisms in Selective Laser Melting: A Review

Zhang

Bai

2017

Chin. J. Mech. Eng.

700

269

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“…He found two instability zones: (1) at a low scanning speed where the track exhibits irregularities attributed to a capillary instability or Plateau-Rayleigh instability, (2) on the contrary, excessively high speed gives rise to the balling effect. Zhou et al 3 suggested that the formation of LPBF defects can be correlated to the melt pool dynamics, oscillations, and Plateau-Rayleigh instability. The melt pool is forced to oscillate by disturbances from the thermocapillary convection, pulsed laser recoil force, and the shear stress in the gas-melt interface.…”

Section: Introductionmentioning

confidence: 99%

Analysis of laser–melt pool–powder bed interaction during the selective laser melting of a stainless steel

Gunenthiram¹,

Peyre²,

Schneider³

et al. 2017

Journal of Laser Applications

140

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The laser powder bed fusion (LPBF) or powder-bed additive layer manufacturing process is now recognized as a high-potential manufacturing process for complex metallic parts. However, many technical issues are still to overcome for making LPBF a fully viable manufacturing process. This is the case of surface finish and the systematic occurrence of porosities, which require postmachining steps. Up till now, the porosity origin remains unclear but is expected to be related to the stability of the process. As a LPBF part is made by the accumulation of hundreds of meters of small weld beads, it also appears to be important to understand all the phenomena that occur during the laser-powder-melt pool (MP) interaction for each single track. For this reason, in the first part of our study, using an instrumented LPBF setup and a fast camera analysis (>10 000 image/s), single tracks were fabricated and analyzed in real time and postmortem. Spatters ejections and powder denudation phenomena were observed together with variations of melt pool dimensions and meltpool instabilities. In turn, the physical origin of this powder denudation and the dynamics of the MP were investigated and discussed.

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“…13 It is well documented that porosity can result in fatigue crack initiation. 5,10,[14][15][16][17][18][19][20] In the work presented herein, the critical size of the pores that are prone to fatigue cracks is investigated and quantified for Inconel 718 material produced by SLM.…”

Section: Introductionmentioning

confidence: 99%

ICME Approach to Determining Critical Pore Size of IN718 Produced by Selective Laser Melting

Sangid

Ravi

Prithivirajan

et al. 2019

JOM

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A degree of porosity is expected in additively manufactured (AM) materials. To aid in the qualification of AM materials, the smallest pore size that results in a debit in the fatigue performance is quantified. In the work presented herein, crystal plasticity simulations are used to identify the stress concentration around pores of various sizes, revealing that a single 20-lm pore or two 10-lm pores (with centers spaced 15 lm apart) localize stress at the pore, as opposed to elsewhere in the microstructure. In situ microtomography and far-field high-energy x-ray diffraction microscopy were used to identify crack formation and the evolution of the grain-level micromechanical fields during cyclic loading. Eighteen cracks were observed (15 at pores, 3 at the surface) at highly stressed grains in a sample, although most did not propagate. The dominant crack was seen to originate from the free surface, which is rationalized by fracture mechanics.

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3D-imaging of selective laser melting defects in a Co–Cr–Mo alloy by synchrotron radiation micro-CT

Cited by 176 publications

References 44 publications

Defect Formation Mechanisms in Selective Laser Melting: A Review

Defect Formation Mechanisms in Selective Laser Melting: A Review

Analysis of laser–melt pool–powder bed interaction during the selective laser melting of a stainless steel

ICME Approach to Determining Critical Pore Size of IN718 Produced by Selective Laser Melting

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