Strength and Toughness of Vanadium Microalloyed Plate Steels

The static phase transformation points and dynamic CCT curves of 5 kinds of vanadium microalloyed plate steels were measured.The steels,processed by recrystallization rolling(RCR) and conventional controlled rolling(CR),respectively were taken to test the mechanical properties and impact toughness.The Ac1 and Ac3 decreased with incresing the effective vanadium and nitrogen.The formation of bainite began while cooling rate reached 5 ℃/s or more,and the pearlite transformation was not be processed with the cooling rate greater than 9 ℃/s.The steel plates by RCR process exhibited higher yield and tensile strengths,but lower elongation and toughness,compared with those by CR process.The precipitation strengthening of the effective nitrogen in the tested steels was presented more remarkably by RCR process than that by CR process.