Strengthening Mechanisms of 27MnSiVS6 Microalloyed Steel Deformed by Four Different Forging Processes

The demand of automotive industries for parts with high overall quality, low costs and reduced time to market, forced suppliers to search alternative materials and manufacturing processes. Hot forgings with microalloyed steel represent an extensive application in automotive parts. The main objective of this work was to study the microstructures by transmission electron microscopy (TEM) and mechanical properties of 27MnSiVS6 microalloyed steel deformed by ausforming, warm forging and hot forging.Workpieces were heated for 15 minutes at 1150 °C before hot forging and 800 °C before warm forging.Two different ausforming tests were carried out: in the first group workpieces were heated for 15 minutes at 1150 °C, cooled to 800 °C at a cooling rate of 8.7 °C/s and then deformed. In the second group the conditions were kept constant except for the heating temperature of 1000 °C. All forged products were air cooled after deformed. Ausforming products presented the best mechanical properties. TEM analysis showed that strengthening by vanadium carbonitride precipitates was the main hardening mechanism of both ausformed and hot forged products while warm forgings were strengthened by the higher dislocation density. © 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of ICM11