Plastic flow and interfacial bonding behaviors of embedded linear friction welding process: Numerical simulation combined with thermo-physical experiment

•The plastic flow behavior of embedded linear friction welding process was revealed by numerical simulation combined with thermo-physical simulation.•On the direction perpendicular to oscillation, thermo-plastic metals are mainly flowing downwardly along welding interface, resulting in inverted “V” shaped interfacial plastic zone and un-welded defects at upper of joint.•High oscillating frequency combined with low pressure and small amplitude are appropriate to improve the upward interfacial plastic flow and suppress the un-welded defects.