Investigations on development customized shape memory alloy structures using wire arc based additive manufacturing and laser based additive manufacturing

Abstract

Shape memory alloys (SMA) have been extensively studied for their unique properties and potential applications in various fields, including damping and vibration control systems, MEMS devices, and biomedical implants. However, their widespread use in bulk structures is limited due to flaws such as strong hysteresis and reduced life cycle. In this work, SMA integrated bulk samples have been prepared using various Additive Manufacturing (AM) methods, such as wire and powder-based systems. A novel approach to fabricating SMA porous structures using Wire Arc Additive Manufacturing has been explored, which was challenging due to issues such as weld pool instability, heat accumulation, residual stress, spatter, and distortion. A laser hybrid system has been used to address these issues by reducing surface roughness (from 24 µm to 2.8 µm) and enhancing mechanical properties and shape recovery (up to 2.4 mm of displacement). Interpass temperature control (200⁰ C-400⁰ C) and interlayer delay (10s-30s) have also been employed to reduce heat accumulation and residual stress and improve mechanical properties such as hardness (802 HV) and tensile strength (900 MPa). Microstructural, structural, and phase transformation analysis have been performed, along with a study of the mechanical properties and shape recovery behavior.