Prediction of internal stresses in heat treatment processes
During various heat treatment processes, internal stresses occur in metallic materials because of non-uniform heating and cooling, phase transformations or irregular microstructure. High internal stresses often lead to defects which sometimes occur rapidly and unexpected. In commercial heat treatment shops, internal stresses often lead to complicated customer claims since it is usually not possible to determine the exact reason of such failures.
Non-destructive measurement of internal stresses can be performed by neutron diffraction. However, this method works with a very small amount of material and thus it cannot be used efficiently in many industrial applications. In heat treatment shops, usually destructive methods based on hole drilling or cutting method (contour method) are applied.
The article describes how the data acquired by the contour method can be used for calibrating of the computer simulation model of internal stresses. Combining the calculated and measured data it is possible to create a very precise model for prediction of internal stresses during diverse heat treatment processes.