Phase transformation and microstructure evolution study in various alloy systems: An insight

Abstract

Phase transformations occurring in various metals like steel, titanium and super alloysis integrated and presented in this paper. In steels, the microalloying with Nb and Nb-Mo decrease in transformation temperature indicates the acceleration of transformation kineticsin turn which affect the microstructure and continuous cooling transformation (CCT) diagram. Incase of titanium alloys, the thermohydrogen treatment (THT) uses hydrogen as temporary alloying element which facilitatethe alloys to be processed at lower stresses and/or temperatures. Thermomechanical processing sschedules are designed baseds ons the β transus temperature to produce a variety of novel microstructures. In the case of crystalline materials, plastic deformations assisted by dislocations and the concentration of dislocation increases with increasing plastic strainthus becoming a precursor of twinning.Stress-strain curves for different alloys suggested the microstructural changes account for deformation induced twinning and martensite transformation.