CRYOGENIC TREATMENT OF MARTENSITIC STEEL WITH MIXED HARDENING

摘要

The temperature T1 is substantially lower than the martensitic transformation temperature Mf, and the time t during which said steel is kept in said cryogenic medium at a temperature T1 from the moment when the hottest part of the steel reaches a temperature lower than the martensitic transformation temperature Mf is at least equal to a non-zero time t1, the temperature T1 (in ° C.) and the time t1 (in hours) being linked by the equation T1=ƒ(t1), the first derivative of the function ƒ relative to t, ƒ′(t), being positive, and the second derivative of ƒ relative to t, ƒ″(t), being negative.