Quenching and tempering can be a real challenge if the finished plates have high yield strength and also high weldability and bendability. Rapid cooling with low plate speed is required and this easily results in bad flatness. Parameters like nozzle angle, turbulence over the surface and position of cam-rolls are important factors. Clogged or worn-out nozzles will also cause flatness issues.
During the installation of a new QT-line, a VeriFlex gauge can pay for itself by shortening tuning time and verify the result. Over time, the flatness quality can be further improved and the gauge will also serve as a guardian and detect flaws and malfunctions in the line. Thin, low alloy quenched plates will always need leveling, but also need to have the right flatness to be “levelable”. This takes time to work out, but without an accurate flatness measurement tool, it is impossible.