S355MC is sensitive to high temperature

When building rail vehicles, during the process of processing, assembling, and welding the components of each part of the car body, due to the existence of stress, the structural parts will be deformed to varying degrees, such as bending and warping, especially after welding.

In order to ensure the assembly accuracy of the car body, it is generally necessary to use a flame method to correct the deformation of the deformed components. However, S355MC steel is a thermomechanically rolled fine-grained structural steel, which is sensitive to high temperature. Under different heating temperatures and cooling rates, the microstructure and mechanical properties of S355MC steel are quite different, which is likely to cause a sharp drop in toughness and plasticity.

With the increase of flame conditioning temperature, the impact properties of S355MC steel decreased significantly; but different conditioning temperatures had little effect on the bending, tensile properties and microhardness of S355MC steel. When S355MC steel is hot-tuned at 700°C and 800°C, its microstructure is equivalent to that of the untuned base metal, and it is ferrite and pearlite distributed in bands along the rolling direction, so this temperature is S355MC steel the most suitable thermal adjustment temperature.