Effect of Thermal Cycle on Grain Growth Kinetics and Formation of CCT Diagram of HSLA Steel S700MC

Abstract The use of high-strength low-alloy (HSLA) steels for welded parts and structural assemblies is becoming increasingly common. Steel S700MC is one of the most widely used HSLA steels, especially in the automotive and manufacturing industries. It combines high-strength properties with good ductility, toughness, and reasonable technological workability in forming and welding. Despite all these advantages, there is still not enough information describing the processes and changes in material properties that occur in different heating and cooling conditions. The present study aims to provide a detailed description of these phenomena through dilatometric tests. The result is primarily an assessment of the effect of thermal cycles on the change in average grain size. Additionally, through the applied dilatometric tests, it was possible to assess the effect of heating rate on the changes in austenitization temperatures. The influence of the cooling rate on the width of the transformation zone was also defined. This is a comprehensive study that has not yet been published for steel S700MC.