DETERMINATION OF NO-RECRYSTALLIZATION TEMPERATURE IN NB-V-TI MICROALLOYED STEEL AND DISCUSSION OF ITS DEFINITION

Using torsion tests, the no-recrystallisation temperature T-nr was det ermined for two cooling rates in a Nb-V-Ti microalloyed steel. The sam e tests made it possible to deduce the Ar-3 phase transformation tempe rature. When T-nr is known, it is possible to establish approximately the conditions for which the strip rolling ol plate rolling of this st eel must be performed to obtain the appropriate microstructure. With t he aid of a recrystallisation model and the results obtained in other work, a discussion is made of the concept of T-nr, the conclusion bein g that it represents the temperature above which the fraction recrysta llised between consecutive passes leaches a value close to 50% and not 100%. This parameter, and the value of Ar-3, can be determined at min imal cost and in a relatively short time. Both economic and time aspec ts are of interest to any steel manufacturer producing hot rolled micr oalloyed steels.