Exploring Salient Microstructural Features Leading to Simultaneous Enhancement in Strength and Ductility of Dual-Phase Steels: Microstructural-based Computational Predictions

Abstract

There has been a great concern in the automotive industries to develop fuelefficient, environmentally friendly, vehicles. One way to achieve such a task is to replace existing materials with lighter steel to reduce the overall weight. Hence, this thesis focuses on proposing novel grades of dual-phase steels, the most commonly used steels in manufacturing car parts, with superior properties in terms of strength and ductility. A model has been proposed that generates the most realistic virtual microstructures that accurately mimics the complexity and the heterogeneity of real microstructures. This model allows the user to freely control all the parameters of the microstructure. Through this, several unexplored parametric studies were conducted and it was concluded that there are some parameters, if optimized properly, can lead to a simultaneous increase in the strength and deformability. For example, it was discovered that if the aspect ratio of martensite particles is increased, it could lead to an increase of 4% and 43% in the UTS and ductility respectively. Moreover, if the martensite phase is interconnected, this could lead to an increase of 2% and 15% in the in the UTS and ductility respectively. Furthermore, if the martensite particle size is reduced, this could lead to an increase of 22% and 50% in the UTS and ductility respective as well. Moreover, it was found that through adding rate-dependent hard nanoparticles into the microstructures can also lead to a simultaneous in both areas. These micromechanical predictions can revolutionize the materials used in the automotive industries, while moving towards a more sustainable future.

Date of Award	May 2015
Original language	American English
Supervisor	Rashid Abu Al Rub (Supervisor)