Tempering relieves these stresses and causes partial decomposition of the martensite into ferrite and cementite. The amount of this partial phase change is controlled by the tempering tem-perature. The tempered steel is not as hard as pure mart-ensite, but is much tougher. This can be observed from the result tabulated above where by the water quenched sprigs have the highest hardness and are the least ductile from all the springs, but after the water quenched steel were tempered it was observed that the hardness of the spring reduced, the toughness and ductility increased when compared to the water quenched springs.