Vanadium carbonitride precipitation
Thermally assisted precipitation of vanadium compounds in the cooled microstructure to achieve high elevated-temperature strength. They act as effective barriers to dislocation movement.
Vanadium is an important alloying element in steel. It forms fine carbonitrides that inhibit grain growth and give the workpiece strength, especially when it gets hot. In welding, this means: when welding vanadium-alloyed steel, you must pay attention to the heat input. If it gets too hot or you cool too quickly, you get a hard, brittle structure that tends to crack. So adjust the cooling to the material. Cooling too quickly is just as bad as cooling too slowly. Stick to the specified interpass temperatures and don't let the weld cool down when welding multiple layers. This keeps the vanadium precipitates finely distributed and the weld remains tough.