Temperature Gradient is a measure of how much change in temperature there is as you go from point to point within a casting. A high temperature gradient means that there is a large temperature change within a short distance within the casting. A low temperature gradient means a small change in temperature from one point to the next.
Temperature Gradient is calculated at each node within the casting as that point hits the Niyama Point on the cooling curve. Temperature Gradient is always calculated in °C per centimeter.
Temperature Gradient can be used to get an idea of whether there was good or poor directional solidification at various points within the casting. In general, higher temperature gradients are good, as steeper temperature gradients mean a greater driving force for solidification.
The disadvantage of Temperature Gradient is that each casting ends up with a different range of values, depending on geometry, and it is hard to compare one casting with the next.
In the figure above, the brightest areas indicate those areas with the lowest temperature gradients, and the poorest directional solidification.