Warm forging of steel with carbon-based coating systems

Theme Tool- and Mold-Making, Forming technology
Project title Warm forging of steel with carbon-based coating systems (Halbwarm DLC2)
Project duration 01.08.2017 – 31.07.2018
Press release

Warm forged parts show significantly better surface and geometric qualities compared to hot forged parts. The drawbacks, however, are higher mechanical stress and increased die wear of the forging tool. Anti-adhesive and extreme hard (up to 3.500 HV) Diamond-Like-Carbon layers (DLC) can be used as protective layers to reduce die wear. Within the first research period, the influence of DLC layers at different forging temperatures on die wear was investigated. It could be shown that DLC layers are capable of reducing die wear, but are also sensitive to high temperatures.

During the second research period DLC layers will be analysed experimentally under various conditions. DLC-multi-layer will be tested at a range of forging temperatures. To measure the local temperature on the die surface, thin layer sensors will be developed in cooperation with the Institute for Surface Technology at TU Braunschweig. Results of local die wear and temperature will be put into relation. Furthermore, experiments with different concentrations of lubrication will be carried out. Based on all the gained information a tribological wear model will be developed.

Publications about the project

Bulk-formed components are used in many applications in automotive and plant engineering. The conditions under which the components are manufactured, often at more than 800°C and thousands of tons of forming force, lead to high die wear. One way to reduce wear is to use suitable protective coatings. Initial basic investigations showed that the use of hard Diamond-like Carbon (DLC) wear-resistant coatings can significantly reduce the tribological effects on the die surface. With new methods such as the use of multilayer layer coatings and temperature measurement on the die surface by use of thin layer sensors, the potential of wear protection for semi-hot massive forming is to be investigated and expanded.

DLC, hot forging, wear


The project no. 356851715 received funding from the German Research Foundation (DFG).


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