A new approach for attaining uniform properties in build direction in additive manufactured components through coupled thermal-hardness model

The theme of the investigation is to strategize uniform build direction properties in additive manufactured components. A computationally efficient model for prediction of layer-wise thermal cycle is developed using control volume approach. The thermal model is coupled with a hardness model to predict the hardness variation in the component. The predicted results are validated with hardness measurement and microstructure observation for a thin walled component of 60 layers produced by wire arc additive manufacturing. The experimental results strongly corroborate the computed cooling rates. The results show how the dynamic control of external conditions (e.g. substrate temperature) can be a very effective measure to attain uniform hardness in the build direction. An optimal strategy is presented for a candidate component. The investigation discloses new strategic steps to achieve uniform mechanical properties vis-a-vis in contrast to the conventional practice of cooling the substrate; the investigation suggests that heating the substrate to a pre-determined temperature and then cooling at a controlled rate during the deposition of layers helps to manage the properties in build direction.