Papers by Keyword: X210CrW12

Abstract: A direct semi-solid bar extrusion process is characterised by inserting a feed stock in a container and extruding through a forming die with a punch. Compared to conventional bar extrusion the use of semi-solid material complicates the process due to the requirement of solidification of the material. To achieve the solidification of the semi-solid bar, different basic tool concepts are presented. With a combination of these concepts experiments were carried out using the steel alloy X210CrW12 to detect the influence of the most influencing parameters press velocity, extrusion channel diameter, length and geometry. Numerical simulations enable a better understanding of the process mechanics like temperature development in the billet and forming die as well as the material flow in the deformation zone.

Abstract: At the Institute of Metal Forming (IBF) current investigations within the framework of the Collaborative Research Centre 289 are mainly concentrated on forming of semi-solid precursor material of the steel grades X210CrW12 and 100Cr6. One important task is the precise temperature for the composition of solid and liquid phase fraction in the preheated billet. Experimental measurements and numerical simulations show significant heat losses during transport of the billet and after its insertion into the die. These developing temperature gradients influence strongly the resulting temperature field in the formed component. In case of the forming tools the critical increase of the temperature depending on the tool material is shown. As fundamental research in the field of thixojoining the temperature development of the inserts is analysed and demonstrates the feasibility of joining higher and lower melting materials into the semi-solid matrix.

Abstract: Rheoforging is a modification of semi-solid forging starting directly from the liquid phase instead of reheating of a billet. In this process semi-solid slurry is prepared by pouring slightly overheated melt over a slope into a holding cup to induce homogenous nucleation. By controlling the casting temperature and holding time in the cup the desired semi-solid slurry with fine, globular microstructure is successfully created. The inline forging trials using this slurry show the principal feasibility of the process.

Abstract: The thixoforming processes join the advantages of conventional forming technologies as forging and casting in respect of the mechanical properties and the practicable geometries. Within the framework of the Collaborative Research Centre 289 at the RWTH Aachen University intensive investigations on semi-solid processing with some steel grades have been running. For this purpose an automated thixoforging plant (thixo-cell) has been developed in a closed cooperation with several industrial partners. With this equipment multi material demonstrator components have been successfully produced by thixojoining using semi-solid X210CrW12 tool steel.

Abstract: This paper deals with the examination of the steel grade X210CrW12 and its suitability for Thixoforming. In the semi-solid state, the microstructure of this steel consists of a homogeneous distribution of globular particles surrounded by liquid. Additionally, carbides are stabile up to fraction liquid contents of approximately 40%. After quenching, this steel reveals a globular austenitic microstructure with eutectic (former liquid phase) at the grain boundaries. Compression tests permit to determine the influence of different process parameters on the properties and the material behaviour in the semi-solid state. Their influence on the microstructure was investigated but not yet highlighted. Further investigations on this steel allow a fine-tuning to establish optimal process windows of the different thixoforming- and rheoforming- routes.