Y. Yang, Y. Bai, Y. Wang, Y. Zhang, C. Weng, W.F. Lu, H. Wang
Journal of Materials Research and Technology 29 (2024) 4327–4344

Abstract. Characterization of the mechanical properties plays an essential role in the post-processing and evaluation of the functionality of the additively manufactured metallic parts. A number of studies have been focused on the tensile properties of additively manufactured metals. However, the quasi-static compression test of the additively manufactured 316L blocks with different heat-treatment conditions and scanning strategies seems to be overlooked in the literature. This paper aims to provide a comprehensive study of compressive mechanical response in plastic deformation of SS316L fabricated by selective laser melting (SLM). The mechanical response and microstructures in compressive deformation is analyzed for three printing strategies with 0°-, 90°- and 67.5°- scanning and three heat treatment conditions (450 °C for 3 h, 1100 °C for 1 h with furnace cool and 1100 °C for 1 h with water quenching) for selective laser melted (SLMed) stainless steel 316L in comparison with wrought stainless steel 316L in this work. Alteration of mechanical properties, microstructure evolution and compressive deformation mechanism is studied. Melt pool features are not significantly affected by low-temperature heat treatment (450 °C for 3 h) but fully dissolved through high-temperature heat treatment (1100 °C for 1 h). High-temperature heat treatment provides a higher resistance to compressive plastic deformation for SLMed 316L compared with the low-temperature heat-treated and as-built samples where more twinnings are observed. The compressive plastic deformation mechanism of 90°- and 67.5°-scanning samples is similar, which mainly results from twinning-induced plasticity. For 0°-scanning samples, the strong crystallographic texture is the main cause of anisotropic deformation. Modelling and simulation have been conducted to explain the anisotropic deformation mechanism of the 0°-scanning strategy. Simulation results suggest that the morphology difference of laser-scanning tracks and melt pools, which leads to material flow along the laser scanning direction, explains the anisotropic deformation mechanism.

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Supported by Singapore Ministry of Education (Project Nos.: MOE-T2EP50120-0010, MOE-T2EP50220-0010, and A-8001225-00-00), and the National Natural Science Foundation of China, China (Grant No.: 51775562).

Z. Zhang, Q. Yan, Y. Zhang, H. Wang, Z. Tong, X. Jiang
Tribology International 200 (2024) 110112

Abstract. Nanoindentation has been widely used to access the micro-/nanomechanical properties of materials. However, the contribution of micro-texture evolution to the anisotropic surface topography, the correlation of dislocation density characteristics with the orientation-dependent plastic volume, and the specifics of inherent slip activities, are still not fully elucidated up to now.Herein, nanoindentation simulations were performed on (001)-, (101)- and (111)-oriented single-crystal aluminium. Dominant slip systems are exactly determined for each surface pile-up for the first time. Moreover, lattice rotation facilitates the formation of pile-ups. The anisotropic plastic volume is controlled by the preference of intrinsic dislocation movement. In (001) sample, dislocations prefer to propagate along the free surface instead of into the depth of the sample, causing its most obvious pile-ups.

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Supported by UK’s EPSRC Future Metrology Hub [grant number: EP/P006930/1], the UK’s STFC Innovation Partnership Scheme (STFC-IPS) project [grant number: ST/V001280/1], the European Union’s Horizon 2020 research and innovation programme [grant number: 767589], the China Scholarship Council (CSC) [grant number: 201806220092], and Singapore Ministry of Education Academic Research Funds [grant numbers: A8001225–00-00 and MOE-T2EP50220–0010].