Ferrite formation and its effect on deformation mechanism of wire arc additive manufactured 308 L stainless steel

•A 308 L stainless steel plate is manufactured by WAAM technology.•A ferrite formation model is proposed.•The material shows relatively consistent strength at different deposited layers.•Single slip and double slip in austenite and ferrite dominate the plastic deformation.•Lathy ferrite and slip bands of austenite are the preferential micro-cracks initiation sites.