Influence of Material Delivery Condition on Residual Stresses and Part Properties During Forward Rod Extrusion

During the manufacturing of semi-finished products, the material is subjected to various forming steps to achieve the final geometry. In order to reduce the work hardening introduced and to ensure a good formability, it is annealed before component manufacturing. Forming technologies like forward rod extrusion are well-established methods for an efficient production of resilient components. In this process however, an inhomogeneous pre-strengthening of the material influences the stress distribution during forming and therefore the mechanical properties and the residual stresses in the component. Since they affect the parts operating behaviour, knowledge of the influence of the delivery condition of the material is necessary. The aim in this paper is to derive dependencies between material properties and the resulting residual stresses and work hardening in the component. Due to the increasing application, ferritic stainless steel X6Cr17 in the skin passed (+LC) and soft annealed (+A) states is used. Residual stresses, microstructure and microhardness distribution of both material states are compared regarding the rods and extruded parts. The effects of the delivery condition are evaluated by comparing process and component properties.