Warm-Innenhochdruck-Umformung

Investigation of the material properties during hot hydroforming

 

Motivation

Compared to conventional materials, the use of light metal alloys or high-strength steels poses a challenge to the metal forming process. This is due to the fact that these materials are very often characterized by a limited formability and high strength at room temperature resulting in increased process forces and early failure. By increasing the temperature of the semi-finished products, the material-related difficulties can be counteracted. Also at hydroforming, recent developments aim at elevating the temperature of wrought material during the forming. However, for a numerical illustration of the process with high-strength steels, there is a lack of a reliable description of flow behavior at high temperatures of the tubular semi-finished parts.

Objectives

The main focus of this research project is to gain further in-depth knowledge of the processes in the semi-finished products. In favor, an existing test methodology is to adapt in order to generate flow curves of various steel materials at elevated temperatures. Furthermore, a method for the numerical simulation of the process, basing on the found results, is meant to be realized.

Approach

In the first phase of the project, an existing test stand should be adjusted in order to determinate velocity as well as temperature-dependent flow curves of various steel materials at elevated temperatures. On the one hand, the yield data obtained in this way are used to carry into execution a numerical simulation of the process, as well as on the other hand to contribute to get further knowledge of the processes in the semi-finished products. Subsequently, a sample geometry shown in the simulation will be matched with experimental data.

 

Realized test stand for hot bulge tests

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Figure 1
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Figure 2