Effect of heat treatment on mechanical properties of medium carbon steel welds

Abstract

The investigation was done on the annealing and hardening heat treatment effect of medium carbon steel welds of different carbon contents. EN 8 and EN 24 grades of steel were grooved and cut for groove welding and normal welding respectively. Annealing and hardening heat treatments were done at different range of temperatures. Brinell's hardness test, tensile test and optical microstructural analysis were performed on steel welds and the results were compared in case of three different zones namely parent zone, heat affected zone and weld zones. After annealing of steel welds of both grades of medium carbon steel welds, a change in the grain size was observed and that lead to the change in its mechanical properties. From present research work, it can be concluded that the heat-treated and un-heat treated specimens have different tensile strengths. Microstructural analysis was done through the optical microscope which showed the presence of pearlite and ferrite in EN8 steel weld and the presence of martensitic along with ferrite and pearlite with respective proportions in EN 24 steel welds.