Dynamic constitutive behavior of LPBFed metal alloys

Abstract

Laser powder bed fused (LPBFed) metal alloys, such as titanium, aluminium, and steel exhibit high specific strength and hold great potential for utilization in the automotive and aerospace sectors. Since automotive and aerospace structures require the materials to withstand dynamic impacts, accurately predicting the flow behavior of LPBF-based alloys under high strain rates becomes critical. In this paper, the dynamic behavior of LPBFed CPTi, AlSi10Mg, and 316L stainless steel under strain rates of approximately 500–3000 s−1 was investigated using a Split Hopkinson Pressure Bar (SHPB). The study compared the stress-strain response and strain rate sensitivity of LPBFed alloys to those of conventionally produced counterparts. Furthermore, Johnson-Cook constitutive model was adopted to predict the flow behavior. The results showed that all alloys exhibit positive strain rate sensitivity under the tested strain rate range, with LPBFed CPTi demonstrating higher flow stress than conventionally built counterparts due to the fine grain size resulting from the additive manufacturing method. Additionally, differences in the performance of AlSi10Mg observed in this study, as compared to the literature, are attributed to differences in building direction and post-processing. Finally, it was demonstrated that the Johnson-Cook model accurately predicts flow behavior for the selected alloys with relatively low error.

Keywords

• Johnson-cook model
• High strain rate
• CP-Ti
• AlSi10Mg
• 316LSS