Characterization of Microstructure and Bending Response of Sheet Material: Influence of Thickness

Bending process is one of the most significant fields of application of sheet metal die. In bending process, it is quite vital that the product should have the desired angle. Furthermore, in order to obtain the desired angle in the bent parts, spring-go and spring-back amounts must be known. In this study, 30o, 60o and 90o bending processes were applied to S235JR (1.0038) sheet metal having 3, 4, 5 and 6 mm thickness. These materials were bent in three forms as heat-untreated, normalized and tempered. In addition to this, the bending process was carried out by making the punch waited on the material for 30 seconds (30 s-punch-wait bending) and by removing the punch without waiting (direct bending). As a result of the experiments it was determined that while the amount of spring-go increased in 30o bending process depending on the thickness of the material, it decreased in 60o and 90o applications. It was also determined that the amount of spring-go in 30 s punch-wait bending process was less than that of the direct bending process. Finally, the effects on the bending process and deformation of heat treatment were revealed by micro-structural characterization.