Determination of no-recrystallisation temperature in Nb-V-Ti microalloyed steel and discussion of its definition

Using torsion tests, the no-recrystallisation temperature T-nr was determined for two cooling rates in a Nb-V-Ti microalloyed steel. The same tests made it possible to deduce the Ar-3 phase transformation temperature. When T-nr is known, it is possible to establish approximately the conditions for which the strip rolling ol plate rolling of this steel must be performed to obtain the appropriate microstructure. With the aid of a recrystallisation model and the results obtained in other work, a discussion is made of the concept of T-nr, the conclusion being that it represents the temperature above which the fraction recrystallised between consecutive passes leaches a value close to 50% and not 100%. This parameter, and the value of Ar-3, can be determined at minimal cost and in a relatively short time. Both economic and time aspects are of interest to any steel manufacturer producing hot rolled microalloyed steels.