Papers by Author: Hermann Müller

Abstract: Brazing of cemented carbides to steel bodies gives rise to the development of complex stress states and distortions which influence the fatigue behaviour of the parts. It is quite important to estimate the residual stresses with numerical methods whose agreement is to be guaranteed with experimental characterization of the brazed parts. In this work FEM simulations and X-ray as well as neutron stress analysis were used to examine the residual stresses of brazed samples. Joints with different geometries and dimensions made of cemented carbide and different steels showing different phase transformation behaviours were investigated.

Abstract: The field of heat treatment of steels offers a large variety of applications for the use of simulation tools. It always includes the development of residual stresses and distortions. The geometry of the part, the composition of the material, the heat treatment process as well as the initial state of the part interact with each other in complex ways and have an influence on the distortion of the part. Using simulation the temporal development of temperature, phases, stresses and distortions while quenching as well as the residual stress distribution and distortion after quenching can be calculated. Transformation plasticity has been proved to be very important for heat treatment simulation. Three steels with identical contents of alloying elements but different carbon contents of 0.2, 0.5 and 0.8 wt. % were analysed. The influence of transformation plasticity during the martensitic transformation on the distortions and residual stresses after quenching of cylinders made out of the three steels was analyzed in simulations and compared to experimental results.