An investigation of the anisotropic properties of heat-treated maraging steel grade 300 processed by laser powder bed fusion

AbstractIn order to explore the possibilities enabled by laser beam powder bed fusion of metals (PBF-LB/M), reliable material models are necessary to optimize designs with respect to weight and stiffness. Due to the unique processing conditions in PBF-LB/M, materials often develop a dominating microstructure that leads to anisotropic mechanical properties, and thus isotropic material models fail to account for the orientation-dependent mechanical properties. To investigate the anisotropy of 18Ni300 maraging steel, tensile specimens were built in seven different orientations. The specimens were heat treated at two different conditions and tested for their tensile properties using digital image correlation (DIC) technique. The microstructure and fracture surfaces are investigated with scanning electron microscope and electron backscatter diffraction. The tensile properties are typical for the material, with a yield strength in the range of 1850 MPa to 1950 MPa, and ultimate tensile strength in the range of 1900 MPa to 2000 MPa. The elastic modulus is 180 GPa, and the elongation at fracture is in the range of 2–6% for all specimens. The strain fields analysed with DIC reveals anisotropic straining in both the elastic and plastic parts of the flow curve for both direct ageing and solution treatment plus ageing specimens. In the former condition, the elastic anisotropy is dictated by the fraction of melt pool boundaries on the transverse surfaces of the specimens. When the material is solution treated prior to ageing, the melt pool boundary effect was supressed.

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An Investigation of the Anisotropic Properties of Heat-Treated Maraging Steel Grade 300 Processed by Laser Powder Bed Fusion

10.21203/rs.3.rs-295821/v1 ◽

2021 ◽

Author(s):

Even Wilberg Hovig ◽

Amin S Azar ◽

Klas Solberg ◽

Knut Sørby

Keyword(s):

Mechanical Properties ◽

Tensile Properties ◽

Maraging Steel ◽

Image Correlation ◽

Powder Bed Fusion ◽

Material Models ◽

Powder Bed ◽

Melt Pool ◽

Heat Treated ◽

Anisotropic Mechanical Properties

Abstract In order to explore the possibilities enabled by laser beam powder bed fusion of metals (PBF-LB/M), reliable material models are necessary to optimize designs with respect to weight and stiffness. Due to the unique processing conditions in PBF-LB/M, materials often develop a dominating microstructure that leads to anisotropic mechanical properties, and thus isotropic material models fail to account for the orientation-dependent mechanical properties. To investigate the anisotropy of 18Ni300 maraging steel, tensile specimens were built in seven different orientations. The specimens were heat treated at two different conditions and tested for their tensile properties using digital image correlation (DIC) technique. The microstructure and fracture surfaces are investigated with scanning electron microscope and electron backscatter diffraction. The tensile properties are typical for the material, with a yield strength in the range of 1850 MPa to 1950 MPa, and ultimate tensile strength in the range of 1900 MPa to 2000 MPa. The elastic modulus is 180 GPa, and the elongation at fracture is in the range of 2-6% for all specimens. The strain fields analysed with DIC reveals anisotropic straining in both the elastic and plastic parts of the flow curve for both direct ageing and solution treatment plus ageing specimens. In the former condition, the elastic anisotropy is dictated by the fraction of melt pool boundaries on the transverse surfaces of the specimens. When the material is solution treated prior to ageing, the melt pool boundary effect was supressed.

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Determination of Anisotropic Mechanical Properties for Materials Processed by Laser Powder Bed Fusion

Advances in Materials Science and Engineering ◽

10.1155/2018/7650303 ◽

2018 ◽

Vol 2018 ◽

pp. 1-20 ◽

Cited By ~ 6

Author(s):

Even W. Hovig ◽

Amin S. Azar ◽

Frode Grytten ◽

Knut Sørby ◽

Erik Andreassen

Keyword(s):

Mechanical Properties ◽

Transversely Isotropic ◽

Tensile Tests ◽

Image Correlation ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Inconel 718 Alloy ◽

Powder Bed ◽

Anisotropic Mechanical Properties ◽

Anisotropic Elastic

Improving the success rate in additive manufacturing and designing highly optimized structures require proper understanding of material behaviour. This study proposes a novel experimental method by which anisotropic mechanical properties of additively manufactured materials can be assessed. The procedure is based on tensile testing of flat specimens, manufactured by laser powder bed fusion (LPBF) at different orientations relative to the build plate. In this study, the procedure was applied to the Inconel 718 alloy. Three identical specimen sets were built, each of which received complementary postprocessing treatments. The tensile tests were carried out on specimens with as-built surface finish. Digital image correlation was used to record the strain field evolution on two perpendicular surfaces of the tensile specimens under loading. An optimization algorithm is also proposed for determining the anisotropic elastic constants using only a few tensile test results. It was observed that both build orientation and postprocessing have strong influence on the anisotropic mechanical properties of the material. The effect of microstructure was also investigated and characterised. Consequently, three transversely isotropic compliance matrices were constructed, representing the effect of the different processing conditions.

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A Review of Factors Affecting the Mechanical Properties of Maraging Steel 300 Fabricated via Laser Powder Bed Fusion

Metals ◽

10.3390/met10091273 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1273 ◽

Cited By ~ 2

Author(s):

Barry Mooney ◽

Kyriakos Kourousis

Keyword(s):

Mechanical Properties ◽

Maraging Steel ◽

Processing Parameters ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Factors Affecting ◽

Powder Bed ◽

Porosity Defects ◽

Research Findings ◽

Microstructure Density

Maraging steel is an engineering alloy which has been widely employed in metal additive manufacturing. This paper examines manufacturing and post-processing factors affecting the properties of maraging steel fabricated via laser powder bed fusion (L-PBF). It covers the review of published research findings on how powder quality feedstock, processing parameters, laser scan strategy, build orientation and heat treatment can influence the microstructure, density and porosity, defects and residual stresses developed on L-PBF maraging steel, with a focus on the maraging steel 300 alloy. This review offers an evaluation of the resulting mechanical properties of the as-built and heat-treated maraging steel 300, with a focus on anisotropic characteristics. Possible directions for further research are also identified.

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Laser powder bed fusion of Ni-based Hastelloy X superalloy: Microstructure, anisotropic mechanical properties and strengthening mechanisms

Materials Science and Engineering A ◽

10.1016/j.msea.2021.142076 ◽

2021 ◽

Vol 827 ◽

pp. 142076

Author(s):

Yingyue Yin ◽

Jianhua Zhang ◽

Jian Gao ◽

Zhenhua Zhang ◽

Quanquan Han ◽

...

Keyword(s):

Mechanical Properties ◽

Powder Bed Fusion ◽

Strengthening Mechanisms ◽

Laser Powder Bed Fusion ◽

Hastelloy X ◽

Powder Bed ◽

Anisotropic Mechanical Properties

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Effect of Texture on the Mechanical Properties Ti Free Grade 300 Maraging Steel Manufactured Using Laser Powder Bed Fusion (LBPF) Process

10.1115/1.0004131v ◽

2021 ◽

Author(s):

Rangasayee Kannan ◽

Peeyush Nandwana

Keyword(s):

Mechanical Properties ◽

Maraging Steel ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed

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Cross-testing laser powder bed fusion production machines and powders: variability in mechanical properties of heat-treated 316L stainless steel

Materials & Design ◽

10.1016/j.matdes.2021.109684 ◽

2021 ◽

pp. 109684

Author(s):

Joni Reijonen ◽

Roy Björkstrand ◽

Tuomas Riipinen ◽

Zaiqing Que ◽

Sini Metsä-Kortelainen ◽

...

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

316L Stainless Steel ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Heat Treated

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In Situ Alloying of a Modified Inconel 625 via Laser Powder Bed Fusion: Microstructure and Mechanical Properties

Metals ◽

10.3390/met11060988 ◽

2021 ◽

Vol 11 (6) ◽

pp. 988

Author(s):

Giulio Marchese ◽

Margherita Beretta ◽

Alberta Aversa ◽

Sara Biamino

Keyword(s):

Mechanical Properties ◽

Base Alloy ◽

Heat Treatments ◽

Inconel 625 ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Melt Pool ◽

Composition Modification

This study investigates the in situ alloying of a Ni-based superalloy processed by means of laser powder bed fusion (LPBF). For this purpose, Inconel 625 powder is mixed with 1 wt.% of Ti6Al4V powder. The modified alloy is characterized by densification levels similar to the base alloy, with relative density superior to 99.8%. The material exhibits Ti-rich segregations along the melt pool contours. Moreover, Ti tends to be entrapped in the interdendritic areas during solidification in the as-built state. After heat treatments, the modified Inconel 625 version presents greater hardness and tensile strengths than the base alloy in the same heat-treated conditions. For the solution annealed state, this is mainly attributed to the elimination of the segregations into the interdendritic structures, thus triggering solute strengthening. Finally, for the aged state, the further increment of mechanical properties can be attributed to a more intense formation of phases than the base alloy, due to elevated precipitation strengthening ability under heat treatments. It is interesting to note how slight chemical composition modification can directly develop new alloys by the LPBF process.

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In Situ CT Tensile Testing of an Additively Manufactured and Heat-Treated Metastable ß-Titanium Alloy (Ti-5Al-5Mo-5V-3Cr)

Applied Sciences ◽

10.3390/app11219875 ◽

2021 ◽

Vol 11 (21) ◽

pp. 9875

Author(s):

Julius Hendl ◽

Sina Daubner ◽

Axel Marquardt ◽

Lukas Stepien ◽

Elena Lopez ◽

...

Keyword(s):

Mechanical Properties ◽

Electron Beam ◽

Tensile Testing ◽

Fusion Process ◽

Fracture Mechanisms ◽

Powder Bed Fusion ◽

Complex Load ◽

Powder Bed ◽

Heat Treated

Additive manufacturing has been considered a suitable process for developing high-performance parts of medical or aerospace industries. The electron beam powder bed fusion process, EB‑PBF, is a powder bed fusion process carried out in a vacuum, in which the parts are melted using a highly focused electron beam. The material class of metastable β‑titanium alloys, and especially Ti‑5Al‑5Mo‑5V‑3Cr, show great potential for use as small and highly complex load-bearing parts. Specimens were additively manufactured with optimised process parameters and different heat treatments used in order to create tailored mechanical properties. These heat-treated specimens were analysed with regard to their microstructure (SEM) and their mechanical strength (tensile testing). Furthermore, in situ tensile tests, using a Deben CT5000 and a YXLON ff35 industrial µ‑CT, were performed and failure‑critical defects were detected, analysed and monitored. Experimental results indicate that, if EB‑PBF-manufactured Ti‑5553 is heat-treated differently, a variety of mechanical properties are possible. Regarding their fracture mechanisms, failure-critical defects can be detected at different stages of the tensile test and defect growth behaviour can be analysed.

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New Grain Formation Mechanisms during Powder Bed Fusion

Materials ◽

10.3390/ma14123324 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3324

Author(s):

Alexander M. Rausch ◽

Julian Pistor ◽

Christoph Breuning ◽

Matthias Markl ◽

Carolin Körner

Keyword(s):

Turbine Blades ◽

Formation Mechanisms ◽

Powder Bed Fusion ◽

Single Crystalline ◽

Powder Bed ◽

Melt Pool ◽

Heat Treated ◽

Planar Front ◽

Grain Formation ◽

The Difference

Tailoring the mechanical properties of parts by influencing the solidification conditions is a key topic of powder bed fusion. Depending on the application, single crystalline, columnar, or equiaxed microstructures are desirable. To produce single crystals or equiaxed microstructures, the control of nucleation is of outstanding importance. Either it should be avoided or provoked. There are also applications, such as turbine blades, where both microstructures at different locations are required. Here, we investigate nucleation at the melt-pool border during the remelting of CMSX-4® samples built using powder bed fusion. We studied the difference between remelting as-built and homogenized microstructures. We identified two new mechanisms that led to grain formation at the beginning of solidification. Both mechanisms involved a change in the solidification microstructure from the former remelted and newly forming material. For the as-built samples, a discrepancy between the former and new dendrite arm spacing led to increased interdentritic undercooling at the beginning of solidification. For the heat-treated samples, the collapse of a planar front led to new grains. To identify these mechanisms, we conducted experimental and numerical investigations. The identification of such mechanisms during powder bed fusion is a fundamental prerequisite to controlling the solidification conditions to produce single crystalline and equiaxed microstructures.

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