Processing Parameter Effects on Residual Stress and Mechanical Properties of Selective Laser Melted Ti6Al4V

Ali, Haider; Ghadbeigi, Hassan; Mumtaz, Kamran

doi:10.1007/s11665-018-3477-5

Cited by 115 publications

(46 citation statements)

References 32 publications

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“…Due to interlayer defects, 75-μm SLM Ti6Al4V blocks were 99.2% dense [40]. For constant energy density of 76.9 J mm 3 [40] lower power 150 W and higher exposure 133-μs combination resulted in 99.9% dense parts. Two hundred watts and 100 μs with 570°C bed temperature resulted in 99.8% dense SLM Ti6Al4V parts [42].…”

Section: Residual Stress Maps Using the Contour Methodsmentioning

confidence: 97%

“…Residual stress is inversely proportional to layer thickness and 75-μm layer thickness resulted in minimum residual stress [40]. For constant energy density of 76.9 J mm 3 , 150 W power and 133-μs exposure combination resulted in the lowest residual stress [40].…”

Section: Effect Of Geometrymentioning

confidence: 93%

“…Residual stress is inversely proportional to bed temperature and 570°C bed pre-heat temperature completely mitigated residual stress [42]. Residual stress is inversely proportional to layer thickness and 75-μm layer thickness resulted in minimum residual stress [40]. For constant energy density of 76.9 J mm 3 , 150 W power and 133-μs exposure combination resulted in the lowest residual stress [40].…”

Section: Effect Of Geometrymentioning

confidence: 93%

“…[42]. Due to interlayer defects, 75-μm SLM Ti6Al4V blocks were 99.2% dense [40]. For constant energy density of 76.9 J mm 3 [40] lower power 150 W and higher exposure 133-μs combination resulted in 99.9% dense parts.…”

Section: Residual Stress Maps Using the Contour Methodsmentioning

confidence: 98%

“…Ali et al [34,[39][40][41][42] measured residual stress with the strain gage hole-drilling method [34,[39][40][41][42][43][44][45] in SLM Ti6Al4V 30 × 30 × 10 mm blocks. Residual stress is inversely proportional to bed temperature and 570°C bed pre-heat temperature completely mitigated residual stress [42].…”

Section: Effect Of Geometrymentioning

confidence: 99%

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Effect of pre-emptive in situ parameter modification on residual stress distributions within selective laser-melted Ti6Al4V components

Ali

Ghadbeigi

Hosseinzadeh

et al. 2019

Int J Adv Manuf Technol

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The effect of thermally induced residual stresses is not dynamically considered during a selective laser melting (SLM) build; instead, it processes using invariable parameters across the entire component's cross-section. This lack of pre-emptive in situ parameter adjustment to reduce residual stresses during processing is a lost opportunity for the process with the potential to improve component mechanical properties. This investigation studied the residual stresses introduced during manufacturing of SLM Ti6Al4V benchmark components and adapted process parameters within a build (layer-to-layer specific modifications) to manage and redistribute stresses within these components. It was found that temporarily switching to an increased layer thickness during the build, directly below highly stressed regions within the component, redistributed stresses and reduced the overall stresses within the structure by 8.5% (within the 80-320-MPa residual stress range) compared to standard invariable SLM processing parameters. This work demonstrates the need for current SLM systems to focus on developing a more intelligent processing architecture with parameters that adapt on the fly during a build, in order to manage residual stresses within the built structure.

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Section: Residual Stress Maps Using the Contour Methodsmentioning

confidence: 97%

Section: Effect Of Geometrymentioning

confidence: 93%

Section: Effect Of Geometrymentioning

confidence: 93%

Section: Residual Stress Maps Using the Contour Methodsmentioning

confidence: 98%

Section: Effect Of Geometrymentioning

confidence: 99%

See 3 more Smart Citations

Effect of pre-emptive in situ parameter modification on residual stress distributions within selective laser-melted Ti6Al4V components

Ali

Ghadbeigi

Hosseinzadeh

et al. 2019

Int J Adv Manuf Technol

Self Cite

View full text Add to dashboard Cite

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Internal Stress Evolution and Subsurface Phase Transformation in Titanium Parts Manufactured by Laser Powder Bed Fusion—An In Situ X‐Ray Diffraction Study

et al. 2021

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Laser powder bed fusion (LPBF) is a metal additive manufacturing technology, which enables the manufacturing of complex geometries for various metals and alloys. Herein, parts made from commercially pure titanium are studied using in situ synchrotron radiation diffraction experiments. Both the phase transformation and the internal stress buildup are evaluated depending on the processing parameters. For this purpose, evaluation approaches for both temperature and internal stresses from in situ diffraction patterns are presented. Four different parameter sets with varying energy inputs and laser scanning strategies are investigated. A combination of a low laser power and scanning speed leads to a more homogeneous stress distribution in the observed gauge volumes. The results show that the phase transformation is triggered during the primary melting and solidification of the powder and subsurface layers. Furthermore, the stress buildup as a function of the part height during the manufacturing process is clarified. A stress maximum is formed below the part surface, extending into deeper layers with increasing laser power. A temperature evaluation approach for absolute internal stresses shows that directional stresses decrease sharply during laser impact and reach their previous magnitude again during cooling.

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A Novel Approach to Robustly Determine Residual Stress in Additively Manufactured Microstructures Using Synchrotron Radiation

et al. 2021

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Introduction 1.1. Microstructure of Additively Manufactured MaterialsAdditive manufacturing (AM) is the subject of many recent publications. [1][2][3] Typical representatives of AM methods for the processing of metallic metals are mainly divided into three categories: wire feeding, powder feeding, and powder bed fusion systems. [3] The latter technique enables the production of metallic structures by layer-wise melting of a thin metal powder bed only using AM equipment and a sliced model generated by a computeraided design (CAD) program. The application of a powder bed in powder-based AM technology facilitates the selective processing of individual layers in complex geometry. The most commonly used powder bed fusion techniques are selective electron beam powder bed fusion (EPBF) and laser powder bed fusion (LPBF). [3,4] EPBF structures are produced in a vacuum atmosphere and at a high temperature, eventually leading to a relatively low residual stress level. In contrast, LPBF processes usually take place at temperatures up to 200 C. The localized energy input and the small melt pool sizes, respectively, in combination with low build chamber temperatures result in high temperature gradients, whereby residual stresses are favored. [5] Generally, the influence of scan vectors and related strategies is a complex topic, which crucially has to be dealt with. Scan vector lengths, orientations, the order of rotation within a specific layer, and its subsequent layers are variables in every building process. Only a very limited number of comprehensive studies have reported on the effect of the scan strategy on the density, microstructure, mechanical properties, and residual stresses of LPBF parts, as clearly stated in previous studies. [5][6][7][8] Already an increased scan path length, e.g., due to a change of cross-section of a part, can result in a severely decreased relative density as well as fundamentally changed microstructure. [9,10] The influence of parameters on the evolution of residual stresses was already numerously studied. [11,12] The authors showed that the residual stresses are mainly influenced by cooling rates, temperature gradients, and melt pool sizes. Also, a minimization of the temperature gradient by powder bed preheating is an option to reduce process-induced stresses. [1,13] The high influence of the laser power and the effect of scan strategies have been characterized.

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Processing Parameter Effects on Residual Stress and Mechanical Properties of Selective Laser Melted Ti6Al4V

Cited by 115 publications

References 32 publications

Effect of pre-emptive in situ parameter modification on residual stress distributions within selective laser-melted Ti6Al4V components

Effect of pre-emptive in situ parameter modification on residual stress distributions within selective laser-melted Ti6Al4V components

Internal Stress Evolution and Subsurface Phase Transformation in Titanium Parts Manufactured by Laser Powder Bed Fusion—An In Situ X‐Ray Diffraction Study

A Novel Approach to Robustly Determine Residual Stress in Additively Manufactured Microstructures Using Synchrotron Radiation

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