Superduplex Ferrite-Austenite Phase Ratio

When welding superduplex steel, you have to watch the ferrite-to-austenite ratio in the microstructure. If there's too much ferrite, the weld becomes brittle and prone to cracking and corrosion. You mainly control the balance through heat input and cooling rate. Don't let the weld cool too quickly, otherwise too much ferrite forms and you lose the required toughness. Keep the interpass temperature within range and work with controlled heat input, then the microstructure will be fine.