Investigating the microstructure and mechanical properties of 316L/TiB2 composites fabricated by laser cladding additive manufacturing

• Published in: Journal of materials research and technology Vol. 29; pp. 28 - 39
• Main Authors: Liu, Yisheng, Chen, Hairui, Han, Rui, Peng, Yong, Wang, Kehong, Li, Xiaopeng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2024; Elsevier
• Subjects: 316L stainless steel; Additive manufacturing; Metal matrix composites; Microstructure; TiB2; Metal matrix composites; TiB2; Additive manufacturing; 316L stainless steel; Microstructure
• ISSN: 2238-7854
• DOI: 10.1016/j.jmrt.2023.12.261

In this paper, the 316L stainless steel matrix composite strengthened by TiB2 was successfully fabricated using laser cladding additive manufacturing technology. The microstructures of 316L/TiB2 with the addition of TiB2 (mass fractions of 0, 3 and 6, respectively) were characterised. Hardness tests and tensile tests were conducted to evaluate the physical and mechanical properties of the samples. The results indicated that all prepared samples exhibit a complex cellular microstructure composed of sub-grains. The matrix phase was verified as γ austenite with a honeycomb-like reinforcement phases forming along the boundaries. Further analysis revealed the net-like reinforcements were (Fe,Cr)2B and M3B2 (M is Cr, Fe, Mo, Ni, Ti) phases. The Microhardness of the samples with 0 wt%,3 wt% and 6 wt% of TiB2 were 148 HV, 170 HV and 186 HV, respectively. The addition of 3 wt% and 6 wt% TiB2 composites increased the yield strength by 22 % and 29 %, respectively, compared to 316L composite. Also, the tensile strength and modulus of elasticity of the reinforcement composites were improved by 8 % and 13 %, respectively. However, the elongation of the reinforcement composites was reduced by 36 % and 47 %, respectively. The reinforcement with high strength and modulus is formed in 316L/TiB2 composite, which leads to a reduction in grain size while enhancing the density of large-angle grain boundaries. Multiple strengthening effects dominated by Orowan strengthening were simultaneously experienced during the preparation process, which improved the mechanical properties of the composites.