Incoherent Precipitation

Incoherent precipitates are particles that don't fit properly into the crystal lattice of the base material. They form when cooling is too fast during welding or when alloying elements don't stay properly dissolved. These things are harder and more brittle than the surrounding structure, and that's exactly where cracks like to start. If you want to avoid them, you need to control the heat and not let the part cool too fast, especially with thick sections. Clean joint preparation and the right heat input are key.