Spark plasma assisted diffusion bonding of titanium and stainless steel: Role of pulse current in diffusion kinetics and microstructural evolution

Abstract This work details the role of pulse current during the spark plasma assisted diffusion bonding of titanium (Ti) and austenitic stainless steel grade AISI 304L (SS 304L) at different temperatures (i.e. 550 °C, 650 °C and 750 °C) with 44 MPa pressure. The microstructural evolution and phase analyses of bonded Ti-SS 304L dissimilar alloys were studied using microscopy, X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) analyses. The alloy (Ti-SS 304L) bonded at 650 °C exhibits the superior bonding of 7 μm interface thickness and exhibits the superior shear strength (429 ± 18 MPa) and Vickers micro-hardness (290 ± 7 HV0.2). The Ti-SS 304L bonded at 550 °C show the voids at interface regions and whereas, at 750 °C exhibits the significant microstructure variation with Widmanstatten structure adjacent to the bonding track lowering the compressive strength to 392 ± 15 MPa.