Search

Since the early 90’s, and from the very early investigations of steel thixoforming, tool materials as well as different kinds of coatings, including different tool steels and fully ceramic systems have been evaluated. The failure mechanisms have been carefully investigated by experiments and simulations and are nearly fully understood. Analysis of the reported literature on this topic shows that there is still a lot to do in this field and no excellent solution exists now a days for steel thixoforming. The aim of this work is to evaluate the thermal and mechanical loadings applied to the tools during steel thixoforming process in order to determine appropriate tool materials and solutions. This evaluation was realized thanks to experimental trials and to the finite elements simulations. The effect of these loadings on the tool’s failure modes are highlighted and compared to the ones observed in classical forming processes. Beyond this, the failure modes of different tool materials and solutions are presented. The tested materials are hot-working tool steels. Other possibilities and tool coating or surface treatments are discussed as well.

This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text. Please make the page settings of your word processor to A4 format (21 x 29,7 cm or 8 x 11 inches); with the margins: bottom 1.5 cm (0.59 in) and top 2.5 cm (0.98 in), right/left margins must be 2 cm (0.78 in). We shall be able to publish your paper in electronic form on our web page http://www.scientific.net, if the paper format and the margins are correct. Your manuscript will be reduced by approximately 20% by the publisher. Please keep this in mind when designing your figures and tables etc.

Investigations on steel thixoforming started in the early 90s and many developments were carried out, mainly driven by the industrialization of the process. After a series of basic investigations on adapted steels and materials as well as near-net shaping investigations, the issue of mass production raised and thus induced some other challenges mainly on die life and process automation and cycling. High working temperatures and components complexity were than the main locks to mass productions. In most of reported literature, none of the involved research group reached or real production and industrialization criteria. The euro group holds most of these research investigations. We have reported many of these results in previous communications and this paper presents a continuity of what have already been presented. Some advanced tooling materials and solutions are presented and applied to a real complex industrial component.

The aim of this work is to evaluate the thermal and mechanical loadings applied to the tools during steel thixoforming process in order to determine appropriate tool materials and solutions. This evaluation was realized thanks to experimental trials and to the finite elements simulations. The effect of these loadings on the tool’s failure modes are highlighted and compared to the ones observed in classical forming processes. Beyond this, the failure modes of different tool materials and solutions are presented. The tested materials are hot-working tool steels. Other possibilities and tool coating or surface treatments are discussed as well.

To improve the industrialization of the process, the study of a thixoforming line stability was proposed. The thixoforming line is fully automated to optimize the repeatability of the experiments. Parameters of the heating cycle, the slug temperature, the tool temperature and the forming speed were studied. For each of them, a range of the expected variations in a steady-state process as well as the effects of these variations on the process itself (forming load and parts quality) were given. These variations are shown to be acceptable. Three different tools were used in the experiments. Some mathematical simulations were realized on the finite elements code Forge2008(c) with a semi-solid constitutive law. The capacity of the model to represent the process stability was discussed. The simulation results are in agreement with the experiment results.

Steel is a particularly challenging material to semi-solid process because of the high temperatures involved and the potential for surface oxidation. Here, the experience of semi-solid processing is reviewed and the current situation in relation to commercial application is assessed. The review will include discussion of the range of potential steel materials which are amenable to thixoformingn and identification of suitable steels; modelling of die fill and rheological properties of semi solid steel; technology considerations for industrialisation; die development and the properties of thixoformed products.

The main goal of this work is to analyze the semi-industrial process of steel thixoforming. The process was carried out using industrial equipment. This equipment consists of a heating device, industrial robots and a hydraulic press. The globular microstructure ensuring thixotropic properties was obtained using the SIMA method. It is one of the simplest and cheapest methods which could be easy applied in the case of steel alloys. In this work, the hot forged rods, commercially produced from 100Cr6 steel, were used. The first part of the work concerned the determination of the proper temperature range, for thixoforming of 100Cr6 steel. Next, some heating tests were carried out in order to obtain as uniform temperature distribution as possible. Heating process was executed using inductive heating. Microstructure analysis of heated samples reveals globular particles surrounded by liquid phase. At last, the thixoforming process was carried out using closed-die forming technique. Completely filled die cavity and good microstructure of the part show that applied process parameters were properly selected.