Numerical calculation of the thermal load during the thixoforming of steel and of the tool life.

金属在半固态下的成形是由于载荷分布复杂，对所用工具的要求很高。除了机械应力外，成形工具还暴露在由合金的初始温度(固相线和液相线之间)和工具框架的最高预热温度产生的极端温度变化应力下。在钢的触变成形中，加工温度约为1300-1500°C，而模具预热温度限制在约300-500°C，因为机器环境主要由钢组成。模具表面也有大量的腐蚀性，特别是通过半固态合金的熔化相。此外，成形过程中的固相分数或从模具中取出时的凝固成分会产生摩擦学攻击。工具和工具成本在形成待制造零件的总成本中占有相当大的份额。降低成本的一种方法是延长刀具寿命。其中一个重要的贡献是在工艺设计和刀具设计中使用有限元模拟来考虑刀具磨损。刀具失效的预测可以通过定制工艺和刀具设计来提高刀具寿命。在拟议的资助期内，重点是由于热机械接触形成疲劳而导致刀具失效的预测。对物质行为的逼真描述是必要的。因此，必须在商用有限元软件中实现用于材料行为数值模拟的两阶段模型。

The forming of metals in the semi-solid state is due to the complex load profile high demands on the tools used. In addition to the mechanical stress the shaping tools are exposed to extreme temperature change stresses that result from the initial temperature (between the solidus and liquidus) of the alloys and in the maximum preheat temperature of the tool frame. In the case thixoforming of steels the processing temperature is about 1300-1500 °C while the mold preheat temperatures are limited to about 300-500 °C, since the machine environment consists mostly of steel. There are also loads of corrosive mold surface, in particular through the melting phase of the semi-solid alloys. Furthermore, there is a tribological attack by the solid-phase fraction during forming or by the solidified component during removal from the mold.The tools and tool costs have a significant share of the thixoforming the total cost of the part to be manufactured. One approach to cost reduction is increasing the tool life. An important contribution to this is taking the tool wear into account by using the finite element simulation during the process design and the tool design. The prediction of tool failure allows the increase of tool life through a customized process and tool design.The emphasis in the proposed funding period is the prediction of tool failure due to thermal-mechanical Thixoforming the fatigue. A realistic depiction of material behavior is necessary. Therefore, a two-phase model for the numerical simulation of material behavior has to be implemented in a commercial FE software.