Selective Laser Melting of Maraging Steels Using Recycled Powders: A Comprehensive Microstructural and Mechanical Investigation

Abstract Application of maraging steels via selective laser melting process in the automotive industry was unavoidably involved in the resistance spot welding with conventional steels. Due to the rapid cooling rate of welding process, selective laser melted maraging steels with unique chemical components and stack microstructure could induced the different microstructural evolution, resulting in the complicated fracture behavior in the spot welds. This paper developed a FEA model to predict the fracture mode of spot welds of DP600 to maraging steel and the effect of test conditions and printing orientations were studied. A method was proposed to calculate the material properties of fusion zone by introducing the combined effect of melting DP600 and maraging steels via selective laser melting, resulting in the accurate prediction of fracture mode and strength of spot welds. An interlayer with lower strength was found around the fusion zone and the fracture path propagated in the region, resulting in the partial interfacial failure of spot welds. Meanwhile, the printing orientation had no significant effect on the fracture mode and strength of spot welds, but the different material properties of maraging steels could affect the fracture displacement of spot welds. These findings could pave a way to guide the application of maraging steels via selective laser melting process in multiple industries, especially in the automotive industry.

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Fusion zone characterization of resistance spot welded maraging steels via selective laser melting

Journal of Materials Processing Technology ◽

10.1016/j.jmatprotec.2019.116253 ◽

2019 ◽

Vol 273 ◽

pp. 116253 ◽

Cited By ~ 1

Author(s):

Cheng Luo ◽

Yansong Zhang

Keyword(s):

Selective Laser Melting ◽

Fusion Zone ◽

Laser Melting ◽

Resistance Spot ◽

Maraging Steels ◽

Spot Welded

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Crystallographic Features of Microstructure in Maraging Steel Fabricated by Selective Laser Melting

10.20944/preprints201805.0373.v1 ◽

2018 ◽

Cited By ~ 1

Author(s):

Naoki Takata ◽

Ryoya Nishida ◽

Asuka Suzuki ◽

Makoto Kobashi ◽

Masaki Kato

Keyword(s):

Orientation Relationship ◽

Selective Laser Melting ◽

Lath Martensite ◽

High Strength ◽

Laser Melting ◽

Maraging Steels ◽

Melt Pool ◽

Rapidly Solidified ◽

Relationship Of ◽

Martensite Structure

This study characterizes the microstructure and its associated crystallographic features of bulk maraging steels fabricated by selective laser melting (SLM) combined with a powder bed technique. The fabricated sample exhibited characteristic melt pools in which the regions had locally melted and rapidly solidified. A major part of these melt pools corresponded with the ferrite (alpha) matrix, which exhibited a lath martensite structure with a high density of dislocations. A number of fine retained austenite (gamma) with a <001> orientation along the build direction was often localized around the melt pool boundaries. The orientation relationship of these fine gamma grains with respect to the adjacent alpha grains in the martensite structure was (111) gamma // (011) alpha and [-101] gamma // [-1-11] apha (Kurdjumov–Sachs orientation relationship). Using the obtained results, we inferred the microstructure development of maraging steels during the SLM process. The results depict that new and diverse high-strength materials can be used to develop industrial molds and dies.

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Air Permeability of Maraging Steel Cellular Parts Made by Selective Laser Melting

Materials ◽

10.3390/ma14113118 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3118

Author(s):

Annadurai Dhinakar ◽

Bai-En Li ◽

Yo-Cheng Chang ◽

Kuo-Chi Chiu ◽

Jhewn-Kuang Chen

Keyword(s):

Energy Density ◽

Maraging Steel ◽

Selective Laser Melting ◽

Laser Melting ◽

Ansys Fluent ◽

Design Guideline ◽

Maraging Steels ◽

Porous Mold ◽

Industry Applications ◽

Experimental Values

Additive manufacturing, such as selective laser melting (SLM), can be used to manufacture cellular parts. In this study, cellular coupons of maraging steels are prepared through SLM by varying hatch distance. Air flow and permeability of porous maraging steel blocks are obtained for samples of different thickness based on the Darcy equation. By reducing hatch distance from 0.75 to 0.4 mm, the permeability decreases from 1.664 × 10−6 mm2 to 0.991 × 10−6 mm2 for 4 mm thick coupons. In addition, by increasing the thickness from 2 to 8 mm, the permeability increases from 0.741 × 10−6 mm2 to 1.345 × 10−6 mm2 at 16.2 J/mm3 energy density and 0.14 MPa inlet pressure. Simulation using ANSYS-Fluent is conducted to observe the pressure difference across the porous coupons and is compared with the experimental results. Surface artifacts and the actual morphology of scan lines can cause the simulated permeability to deviate from the experimental values. The measured permeability of maraging steel coupons is regression fit with both energy density and size of samples which provide a design guideline of porous mold inserts for industry applications such as injection molding.

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Effect of Heat Treatment Condition on Microstructural and Mechanical Anisotropies of Selective Laser Melted Maraging 18Ni-300 Steel

Metals ◽

10.3390/met10030410 ◽

2020 ◽

Vol 10 (3) ◽

pp. 410 ◽

Cited By ~ 3

Author(s):

Dohyung Kim ◽

Taehwan Kim ◽

Kyeongsik Ha ◽

Jeong-Jung Oak ◽

Jong Bae Jeon ◽

...

Keyword(s):

Heat Treatment ◽

Tensile Strength ◽

Selective Laser Melting ◽

Solution Heat Treatment ◽

Laser Scanning ◽

Solution Treatment ◽

Heat Treatments ◽

Mechanical Anisotropy ◽

Laser Melting ◽

Maraging Steels

18Ni-300 maraging steel produced by the selective laser melting (SLM) process has a unique microstructure that is different from that of the same alloy processed by conventional methods. In this paper, maraging steels were fabricated by the selective laser melting process and their microstructures and mechanical properties were investigated in terms of post heat treatment conditions. Moreover, the effect of different heat treatments on the mechanical anisotropy was studied in detail. The micro Vickers hardness in the as-built state was around 340 Hv and could be increased to approximately 600 Hv by aging heat treatments. It was found that the solution heat treatment was not necessary to obtain a fully hardened state. From tensile tests of the maraging steels heat treated with different conditions, it was found that the highest strength was achieved by aging and solution treatment (ST) temperatures lower than the commonly used temperatures. In the direction parallel to the laser scanning, the highest ultimate tensile strength was obtained when 450 °C aging was done without solution heat treatment. In the other two directions tested, i.e., directions normal to the building and 45 degrees to the laser scanning direction, the highest tensile strength was obtained when aging was done at 450 °C after 750 °C solution treatment.

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High Strength X3NiCoMoTi 18-9-5 Maraging Steel Prepared by Selective Laser Melting from Atomized Powder

Materials ◽

10.3390/ma12244174 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4174 ◽

Cited By ~ 3

Author(s):

Angelina Strakosova ◽

Jiří Kubásek ◽

Alena Michalcová ◽

Filip Průša ◽

Dalibor Vojtěch ◽

...

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Maraging Steel ◽

Selective Laser Melting ◽

High Strength ◽

Industrial Applications ◽

Tensile Yield Strength ◽

Laser Melting ◽

Maraging Steels ◽

3D Printed

Maraging steels are generally characterized by excellent mechanical properties, which make them ideal for various industrial applications. The application field can be further extended by using selective laser melting (SLM) for additive manufacturing of shape complicated products. However, the final mechanical properties are strongly related to the microstructure conditions. The present work studies the effect of heat treatment on the microstructure and mechanical properties of 3D printed samples prepared from powder of high-strength X3NiCoMoTi 18-9-5 maraging steel. It was found that the as-printed material had quite low mechanical properties. After sufficient heat treatment, the hardness of the material increased from 350 to 620 HV0.1 and the tensile yield strength increased from 1000 MPa up to 2000 MPa. In addition, 3% ductility was maintained. This behavior was primarily affected by strong precipitation during processing.

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