We would like to obtain a hardness of HRC 38 to 40 in quenched steel. What range

Question:

We would like to obtain a hardness of HRC 38 to 40 in quenched steel. What range of cooling rates would we have to obtain for the following steels? Are some steels inappropriate for achieving these levels of hardness? (See Figure 13-21 and Table 13-3)
(a) 4340;
(b) 8640;
(c) 9310;
(d) 4320;
(e) 1050; and
(f) 1080.