Development of a methodology for fatigue life time assessment of highly loaded hot forming dies based on advanced material models.

The deeper understanding of the deformation and damage behaviour of the investigated tool steel and the life prediction models based on it obtained in this project will make an important contribution to the computational design of hot forming dies. Based on the calculation concept to be developed, constructive measures can already be taken in the design phase in order to increase the die life time of forging dies with the help of numerical simulation, since early detection of sources of defects is made possible. Another associated advantage is that series production readiness for a forged product can be achieved more quickly, as cost-intensive and time-consuming testing cycles can be avoided.

The sub-objectives in the first project period were achieved and a database is available for the considered hot work tool steel X38CrMoV5-3 with a quenched and tempered hardness of 54 HRC in the initial condition for the cyclic plastic material behaviour at different ageing conditions as well as the corresponding alternating plasticity model and their numerical implementation. The objectives for the second period are therefore:

• Extension of the material database for the considered hot work tool steel X38CrMoV5-3 with a tempering hardness of 54 HRC using fatigue tests
• Development of the mechanism-based model for fatigue life time evaluation
• Determination of the material parameters of the fatigue life time model based on the available material data
• Implementation of the life time model for the FEM
• Validation of the developed concept for service life time evaluation on the basis experimental serial forging tests