Neutron diffraction bulk texture study with impact property correlation of electron beam welded dissimilar Fe-7%Al alloy to steel joints

Abstract

Present work focused on the crystallographic bulk texture study of dissimilar Fe-7percentage Al alloy to mild steel joints by electron beam welding using time-of-flight neutron diffraction technique. Textural properties directly correlated with V-notch Charpy impact study. Different processing conditions like the use of beam oscillation and by changing welding speed on texture change and its impact on the performance of the joint was evaluated. Neutron diffraction was performed using general material diffractometer beamline at ISIS neutron radiation source. Texture analysis and their variation obtained in terms of pole-figures, inverse pole figures and orientation distribution functions (ODFs). Beam oscillation shows a uniform and ordered textured grains in both fusion zone (FZ) and heat-affected zone (HAZ) due to more heat mixing that reduced unidirectional solidification gradient. ODF study reveals more gamma fibre components in both FZ and HAZ compared to its non-oscillating counterparts and higher welding speed joints, which predominantly shows more Goss, rotated Goss and cube/alpha fibre components. Charpy impact strength shows approximately 60% improvement in value for the joints, which was prepared by using beam oscillation whereas 20% reduction for higher welding speed condition. Also, X-ray tomography study of Charpy broke sample showed very lesser and shallow cracks and in smaller volume percentage of 0.45 compared to joints produced by the non-oscillating beam showing maximum value of 2.99%.