Influence of post heat treatments on anisotropy of mechanical behaviour and microstructure of Hastelloy-X parts produced by selective laser melting

Tomus, Dacian; Tian, Ye; Rometsch, Paul; Heilmaier, Martin; Wu, Xinhua

doi:10.1016/j.msea.2016.04.086

Cited by 239 publications

(81 citation statements)

References 13 publications

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“…SLM machine processing parameters influence the microstructure of the final material. Most 316L SLM fabricated materials exhibit melt pools [9][10][11][12][13], and an anisotropic microstructure with elongated grains in the fabrication direction [5,14,15]. Precipitates have previously been observed in as-built 316L SLM fabricated stainless steels.…”

Section: Introductionmentioning

confidence: 93%

Microstructure and mechanical properties relationship of additively manufactured 316L stainless steel by selective laser melting

Puichaud

Flament

Chniouel

et al. 2019

EPJ Nuclear Sci. Technol.

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Additive manufacturing (AM) is rapidly expanding in many industrial applications because of the versatile possibilities of fast and complex fabrication of added value products. This manufacturing process would significantly reduce manufacturing time and development cost for nuclear components. However, the process leads to materials with complex microstructures, and their structural stability for nuclear application is still uncertain. This study focuses on 316L stainless steel fabricated by selective laser melting (SLM) in the context of nuclear application, and compares with a cold-rolled solution annealed 316L sample. The effect of heat treatment (HT) and hot isostatic pressing (HIP) on the microstructure and mechanical properties is discussed. It was found that after HT, the material microstructure remains mostly unchanged, while the HIP treatment removes the materials porosity, and partially re-crystallises the microstructure. Finally, the tensile tests showed excellent results, satisfying RCC-MR code requirements for all AM materials.

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Section: Introductionmentioning

confidence: 93%

Microstructure and mechanical properties relationship of additively manufactured 316L stainless steel by selective laser melting

Puichaud

Flament

Chniouel

et al. 2019

EPJ Nuclear Sci. Technol.

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“…Other works of Dacian et al [ 23 , 24 ] reported that lower concentrations of Si, Mn, and C can result in minor formation of microsegregation along the grain boundaries, consequently generating less cracks. In particular, using a computational thermodynamics approach, in a subsequent work Dacian et al [ 18 ] proposed that the cracking mechanism is mainly influenced by the quantity of Si and C whereas Mn has a negligible effect.…”

Section: Introductionmentioning

confidence: 98%

“…The first studies on LPBF HX attempted to determine the specific process parameters in order to eliminate cracks, establishing that it was not possible to obtain crack-free components [ 17 , 19 ]. Afterwards, much research on LPBF HX alloy has been focused on chemical composition modifications in order to reduce cracks, which are typically classified as hot tearing or hot cracking, occurring during the last period of solidification [ 14 , 18 , 23 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

Study of the Microstructure and Cracking Mechanisms of Hastelloy X Produced by Laser Powder Bed Fusion

et al. 2018

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Hastelloy X (HX) is a Ni-based superalloy which suffers from high crack susceptibility during the laser powder bed fusion (LPBF) process. In this work, the microstructure of as-built HX samples was rigorously investigated to understand the main mechanisms leading to crack formation. The microstructural features of as-built HX samples consisted of very fine dendrite architectures with dimensions typically less than 1 µm, coupled with the formation of sub-micrometric carbides, the largest ones were mainly distributed along the interdendritic regions and grain boundaries. From the microstructural analyses, it appeared that the formation of intergranular carbides provided weaker zones, which combined with high thermal residual stresses resulted in hot cracks formation along the grain boundaries. The carbides were extracted from the austenitic matrix and characterized by combining different techniques, showing the formation of various types of Mo-rich carbides, classified as M6C, M12C and MnCm type. The first two types of carbides are typically found in HX alloy, whereas the last one is a metastable carbide probably generated by the very high cooling rates of the process.

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“…The molten pool boundaries of sample 2 were generated from layer-by-layer overlapping along the z-axis which are called as "layer-layer" molten pool boundaries. Correspondingly, those generated through track-by-track overlapping in the X-Y plane are referred to as "track-track" 8 Complexity molten pool boundaries [25]. Melt tracks were partially remelted, resulting in an increase in density of SLM parts.…”

Section: Experimental Investigationmentioning

confidence: 99%

3D Thermal Finite Element Analysis of the SLM 316L Parts with Microstructural Correlations

Zhao

2018

Complexity

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In this study, a multitrack and multilayer finite element model was developed to simulate the temperature field and molten pool contours during selective laser melting (SLM) of 316L stainless steel powder under different scanning strategies. The simulated temperature field and its evolution over time were compared with experimental measurement results. Furthermore, a correlation was established by the presented results between the predicted thermal behavior and the microstructure of SLM specimens. It was found that the maximum temperature of the molten pool rose slightly with the increase of scanning tracks, but when laser scanned multilayer, the maximum temperature rose first and then decreased. There are large columnar crystals in molten pools, growing in the direction of the maximum temperature gradient. The microstructure defects are more likely to occur at the bonding regions between adjacent layers and islands, where the heat and stress are concentrated. Moreover, the results also showed that the scanning strategy affects the microstructure and microhardness. Also, the SLM 316L parts under the S-shaped strategy had finer grains and a higher Vicker hardness than that formed under the island strategy.

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Influence of post heat treatments on anisotropy of mechanical behaviour and microstructure of Hastelloy-X parts produced by selective laser melting

Cited by 239 publications

References 13 publications

Microstructure and mechanical properties relationship of additively manufactured 316L stainless steel by selective laser melting

Microstructure and mechanical properties relationship of additively manufactured 316L stainless steel by selective laser melting

Study of the Microstructure and Cracking Mechanisms of Hastelloy X Produced by Laser Powder Bed Fusion

3D Thermal Finite Element Analysis of the SLM 316L Parts with Microstructural Correlations

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