Microstructure and mechanical properties of maraging 18Ni-300 steel obtained by powder bed based selective laser melting process
ISSN: 1355-2546
Article publication date: 7 July 2020
Issue publication date: 20 August 2020
Abstract
Purpose
The purpose of this paper is to maraging 18Ni-300 steel fabricate by powder bed based selective laser melting (SLM) process. Microstructure and mechanical properties of the maraging steel part before and after heat treatment at a slow cooling rate were investigated.
Design/methodology/approach
The microstructure of the printed part was observed by optical microscopy and scanning electron microscopy. The phases were determined by X-ray diffraction. The surface roughness of the part was recorded by a profilometer. The tensile properties and microhardness of the parts before and after heat treatment were characterized by an electronic universal tensile testing machine and a Vickers hardness tester, respectively.
Findings
Maraging 18Ni-300 steel part comprised of the martensitic phase and a small fraction of austenite phase. After heat treatment, the volume fraction of austenite slightly increased. The surface roughness of the part was about 96 µm. The printed part was dense, but irregular pores were present. The yield strength, ultimate tensile strength (UTS), elongation and Young’s modulus of as-fabricated parts were 554.7 MPa, 1173.1 MPa, 10.9% and 128.9 GPa, respectively. The yield strength, UTS, elongation and Young’s modulus of as-treated parts were 2065 MPa, 2225 MPa, 4.2% and 142.5 GPa, respectively. The microhardness values of surface and cross-section of the as-fabricated part were 407.1 HV and 443.0 HV, respectively. After short-time heat treatment, the microhardness values of the surface and cross-section of the part were 542.7 HV and 567.3 HV, respectively. After long-time heat treatment, the microhardness values of the surface and cross-section of the part were 524.4 HV and 454.8 HV, respectively. The microhardness and tensile strength increased significantly with decreasing elongation due to the changes in phases and microstructure of the parts after heat treatment.
Originality/value
This work studied the effect of heat treatment at 550°C combined with a subsequent slow cooling rate on microstructure and mechanical properties of maraging 18Ni-300 steel obtained by the powder bed based SLM process.
Keywords
Acknowledgements
This research paper was supported by funding of Changzhou Sci and Tech Program (Grant no. CJ20190041), the Funding of Changzhou High Technology Research Key Laboratory of Mould Advanced Manufacturing (No. CM20173001), the National Natural Science Foundation of China (No. 51875053), and Ningbo Natural Science Foundation (No. 2014A610057 and No. 2018A610064). The authors want to thank Mr Hongbo Liu from Wei Fang 3D Technology Co., LTD for his experimental help and Dr Lei Zhang from the Changshu Institute of Technology for his helpful contribution to the characterization of the parts after tensile testing. The authors are also grateful to their colleagues for their essential contribution to this work and to Dr Haijun Pan for discussion.
Citation
Wu, W., Wang, X., Wang, Q., Liu, J., Zhang, Y., Hua, T. and Jiang, P. (2020), "Microstructure and mechanical properties of maraging 18Ni-300 steel obtained by powder bed based selective laser melting process", Rapid Prototyping Journal, Vol. 26 No. 8, pp. 1379-1387. https://doi.org/10.1108/RPJ-08-2018-0189
Publisher
:Emerald Publishing Limited
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