Precipitation Hardening via Incoherence
An increase in the strength of metallic materials through the incorporation of finely distributed, distinct phase particles whose lattice structure is no longer coherent with the matrix. This effectively impedes dislocation movement via stress fields.
Precipitation hardening by incoherent particles means: during cooling, small hard particles form in the structure that don't fit into the lattice of the base material. They block the mobility of dislocations, making the material harder and stronger. In welding, this is a double-edged sword. If the heat-affected zone cools too slowly, it can lead to stresses and cracks. You have to control the cooling, otherwise the structure becomes uneven and the weld brittle. Clean, controlled cooling is key to use this effect for a stable weld.