Cellular Solidification
Formation of columnar crystal structures with a cellular cross-section at the solidification front under high temperature gradients and low alloy contents.
Cellular solidification is known from the microstructure of the weld: during solidification, fine, cell-like crystals form, depending on the cooling direction. This happens especially in unalloyed or low-alloy steels when heat dissipates well. If you cool the weld too quickly, stress builds up and cracks can occur. Therefore, controlling the cooling is the be-all and end-all. Don't let the weld cool down suddenly, but maintain the heat where possible – for example by preheating or slow cooling. In the end, you want a fine, tough structure without cracks. So: keep an eye on heat management, then it'll be fine.