Microstructural heterogeneity and mechanical anisotropy of 18Ni-330 maraging steel fabricated by selective laser melting: The effect of build orientation and height

Yao, Yi; Wang, Kaiwen; Wang, Xiaoqing; Li, Lin; Cai, Wenjun; Kelly, Samuel; Esparragoza, Natalia; Rosser, Matthew; Yan, Feng

doi:10.1557/jmr.2020.126

Cited by 26 publications

(9 citation statements)

References 40 publications

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“…Thus, it is thought that the cooling rate is the dominant factor controlling the structural state, and that the temperature of the solidified material must quickly fall to a low enough fraction of T g such that continuous relaxation does not occur during the build. This is identical to reports of microstructure heterogeneity along the build height in crystalline metals, where finer scale grains, second phase cell structures, and/ or martensitic structures are observed with higher hardness at the bottom of the build due to the higher cooling rate, yet the subsequent heat input during the build is insufficient to coarsen the bottom region microstructure relative to the higher locations [53][54][55][56][57].…”

Section: Discussionsupporting

confidence: 88%

Advanced structural analysis of a laser additive manufactured Zr-based bulk metallic glass along the build height

et al. 2022

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Additive manufacturing of bulk metallic glasses (BMGs) has opened this material class to an exciting new range of potential applications, as bulk-scale, net-shaped amorphous components can be fabricated in a single step. However, there exists a critical need to understand the structural details of additive manufactured BMGs and how the glassy structure is linked to the mechanical properties. Here, we present a study of structure and property variations along the build height for a laser powder bed fusion (LPBF) processed Zr-based BMG with composition Zr59.3Cu28.8Nb1.5Al10.4 commercially termed AMZ4, using hardness testing, calorimetry, positron annihilation spectroscopy, synchrotron X-ray diffraction, and transmission electron microscopy. A lower hardness, more rejuvenated glassy structure was found at the bottom of the build compared to the middle region of the build, with the structure and properties of the top region between the two. Such differences could not be attributed to variability in chemical composition or crystallisation; rather, the softer bottom region was found to have a larger medium range order cluster size, attributed to heat dissipation into the build plate during processing, which gave faster cooling rates and less reheating compared to the steady-state middle of the build. However, at the top of the build less reheating occurs compared to the middle, leading to a somewhat softer and less relaxed state. Graphical abstract

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Section: Discussionsupporting

confidence: 88%

Advanced structural analysis of a laser additive manufactured Zr-based bulk metallic glass along the build height

et al. 2022

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“…For example, researchers have applied SEM and EDS to characterize the microstructure and chemical composition in 3D printed steel molds (Ref 16,17). In addition, EBSD analysis was conducted to determine the crystallographic texture and grain size distribution in molds ( Ref 18,19). SEM, EDS and XRD were also used to identify the microstructure and phases present in molds (Ref 20-22).…”

Section: Conventional Techniques: Sem Tem Xrdmentioning

confidence: 99%

Microstructure Evolution in Additively Manufactured Steel Molds: A Review

Law

Wong

Wang

et al. 2021

J. of Materi Eng and Perform

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Over the last decade, developments in metal additive manufacturing (AM) have opened up new possibilities in various industries. Current metal AM technologies are now capable of processing a larger selection of metals, including steel mold materials such as H13 and P20. In the injection molding industry, mold makers have implemented metal AM technologies to 3D print steel molds. The main challenge currently faced by mold makers is to 3D print steel molds with mechanical properties that are comparable with conventionally made ones. Research on the microstructure evolution in 3D printed steel molds provide the necessary information for tailoring the moldÕs microstructure and improving its mechanical properties. This review presents a unique perspective on the microstructure evolution in 3D printed steel molds. The microstructure evolution is discussed according to two major processing stages. Stage 1 describes the formation of the moldÕs microstructure in as-built condition after it has solidified from its molten state. Subsequently, Stage 2 describes the changes in the moldÕs microstructure post-heat treatment. This review also summarizes the various experimental techniques and numerical models used to study the microstructure evolution in 3D printed components. Advances in experimental microstructure characterization techniques enable researchers to investigate microstructure evolution in situ during metal AM processes. Coupled thermalmicrostructure numerical models serve as an alternative approach for predicting grain growth in 3D printed components. The review concludes by summarizing future prospects in mold making and metal AM research in general.

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“…However, the elongation at break of specimen groups Tz and T45 specimens are quite low in comparison with Tx and Ty. It has been reported by several researchers that the changing in build orientation can result in the microstructural heterogeneity of the SLM components [10]. Dong et al studied the thermal transfer mechanisms of AlSi10Mg specimens and derived the microstructural variations due to the build orientations of the components [8,9,11].…”

Section: Tensile Test Resultsmentioning

confidence: 99%

“…A homogenous microstructure provides high mechanical strength to the components and can accommodate strain which can reduce cracking. However, due to the high cooling rates in the SLM process, which is in the range of 10 6 -10 8 • C/s, achieving equiaxed grain is a challenge [5,[8][9][10][11]. Thus, it is essential to study the behaviour of SLM components built in different direction.…”

Section: Introductionmentioning

confidence: 99%

Damage Progress Classification in AlSi10Mg SLM Specimens by Convolutional Neural Network and k-Fold Cross Validation

et al. 2022

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In this study, the damage evolution stages in testing AlSi10Mg specimens manufactured using Selective Laser Melting (SLM) process are identified using Acoustic Emission (AE) technique and Convolutional Neural Network (CNN). AE signals generated during the testing of AlSi10Mg specimens are recorded and analysed to identify their time-frequency features in three different damage evolution stages: elastic stage, plastic stage, and fracture stage. Continuous Wavelet Transform (CWT) spectrograms are used for the processing of the AE signals. The AE signals from each of these stages are then used for training a CNN based on SqueezeNet. Moreover, k-fold cross validation is implemented while training the modified SqueezeNet to improve the classification efficiency of the network. The trained network shows promising results in classifying the AE signals from different damage evolution stages.

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Microstructural heterogeneity and mechanical anisotropy of 18Ni-330 maraging steel fabricated by selective laser melting: The effect of build orientation and height

Abstract: Abstract

Cited by 26 publications

References 40 publications

Advanced structural analysis of a laser additive manufactured Zr-based bulk metallic glass along the build height

Advanced structural analysis of a laser additive manufactured Zr-based bulk metallic glass along the build height

Microstructure Evolution in Additively Manufactured Steel Molds: A Review

Damage Progress Classification in AlSi10Mg SLM Specimens by Convolutional Neural Network and k-Fold Cross Validation

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