Materials and Manufacturing of Container and Stem Forgings for the Extrusion Industry

Abstract

Extrusion tools, such as containers and stems, are expensive components, and it is important to use the most suitable materials to gain a long service life. It has to be pointed out, however, that not only the applied materials determine the life time of these tools, but also melting and forging techniques as well as heat treatment have an essential impact. For many years, Bohler Special Steel Open Die Forge has been a supplier of forged high-quality components for the extrusion industry, e. g. mantels, liner, liner holder, stems, and accessories for containers. This paper reports on the experiences and research activities in the fabrication of forged components for containers and stems for the extrusion industry and covers material selection up to achieved mechanical properties and ultrasonic test results. Moreover, heating and Finite Element Method (FEM) modelling of stress distributions in the container during the extrusion process in order to optimize and predict the lifetime of these components are discussed. From the material side, the focus is set on the classical 5% chromium steel class, up to the high-alloyed and sophisticated Maraging steels for stem application, mainly in indirect extrusion processes, with the highest compressive stresses required.