Fabrication of 8Cr-2W ferritic steel tile for reduction in toroidal magnetic field ripple on JT-60U

The objectives are to fabricate the ferritic steel for the reduction in the toroidal magnetic field ripple on JT-60U. The ferritic steel (8Cr-2W-0.2V) is selected by saturated magnetization and fabrication processes with more than 20 tons melting are reported. Although the magnetic properties of the plates fabricated are clarified, the little variation is observed but the saturated magnetization is lower than expected. Additional material conditions are clarified to improve the saturated magnetization without degradation of mechanical properties but it is decided not to adapt this process on grounds of cost-effectiveness.