Residual stresses in cast iron components – Simulated results verified by experimental measurements

Abstract

The aim of this work was to investigate how accurately residual stresses can be simulated in a cast component. The reason why this is important is that a simulation that also considers residual stresses can be used to design cast components more weight- and cost-efficient. The verification was done by comparing simulated results with physical measurements on cylinders made of ductile iron. The measurements were performed with two methods, sectioning and holedrilling. These methods were applied on both as-cast and machined cylinders. The simulations were based on process data from casting trials and material data from the simulation software database. The material data for the heat conductivity of the molding sand was fitted to get a good conformity between measured and simulated temperatures. This was done to ensure that the residual stress simulation used a relevant temperature history. It turned out that the simulation was in good agreement with results from the sectioning measurements of the axial stress while results from the hole-drilling measurements were contradictive. These results were contradictive for both as-cast and machined cylinders. It can therefore be concluded that residual stresses measured by the sectioning method resulted in good conformity with the simulated σz stresses. It was also concluded that the feeders, acting as extra heat sources, affects residual stresses locally and contributes to differences in stresses beneath the feeders, compared to corresponding areas between the feeders. It was also found that the resolution of the mesh needs to be finer to take into account changes in the stresses with increments in depth when using the hole drilling method.