•The Cup/Fe composite coatings are fabricated via PTA alloying process.•PTA heat input affects the synthesis of the composite coatings.•The Cu-rich particles are formed in the coatings due to liquid phase separation.•Cu film is formed during friction process, which can act as a lubricant.To improve the tribological properties of automobile stamping dies, Cu-rich particulate composite coatings were synthesized via plasma transferred arc alloying (PTA) of copper on ferritic nodular cast iron substrates. The plasma transferred arc heat input has an important effect on the synthesis of composite coatings. At a low heat input of 202 J/mm, a double-layer structure with both a Cu-rich layer and an Fe-rich layer is observed. As the heat input increases, the volume of the Cu-rich layer significantly decreases because the Cu is further mixed into Fe-rich layer. When the heat input is increased to 260 J/mm, a single Cu-rich particulate composite coating is synthesized in the molten pool. Microstructural analysis reveals that Fe-rich particles are embedded in the Cu-rich matrix, while Cu-rich particles are embedded in the Fe-rich matrix, which consists predominantly of residual austenite, acicular martensite and an interdendritic eutectic carbides. The microhardness of the Cu-rich particulate composite coatings is measured, which is much higher than that of the untreated substrate material but lower than that of the remolten layer without the Cu additive. Sliding wear tests are carried out on the composite coatings at room temperature (RT) and 773 K. The results exhibit a much better wear resistance of the composite coating compared to the untreated material. The Cu-rich particles contained in the composite coatings play an important role in the antifriction properties, which can be attributed to the formation of protective Cu films on the friction surface.

•Two die structures were designed to study the sheet forming process with coil discharge at different positions.•It is difficult to control the forming accuracy with free die no matter what value of the coil rotation angle is.•An optimum coil rotation angle exists for sheet contact with flat-bottomed die for each coil discharge position.•3D profilometry provided validation of numerical simulation.In order to provide guidance to future forming of deep and large parts, 3D numerical simulation was used to study large sheet deformation process. We designed two different die structures to analyze forming process, during which the coil discharged successively at different positions. The value of material flowing, the effect of subsequent deformation on deformed sheet region, strain distribution and forming quality are all analyzed and discussed. We found flat-bottom die, two times discharging in one position, discharging voltage and coil rotation angle are key factors, which effect final forming quality directly.