First results on the effect of direct quenching on mechanical properties and anelastic relaxation in CLAM steel

China low-activation martensitic (CLAM) steel subjected to different heat treatment was studied by internal friction method. The temperature dependencies of internal friction Q−1 of the steel were measured by torsion pendulum in the temperature range from the room temperature to 700 K using free decay method. The water-quenched sample and air-cooling one both present C–Cr associates with three Cr atoms. After tempering, C–Cr associates with three Cr atoms remained high in air-cooling sample but almost erased in water-quenched one. This showed that cooling rate influenced the stability of C–Cr associate. The mechanical property of CLAM steel subjected to different heat treatment was also presented.