Experimental Method for the Controlled Cooling of Steel Sections with Varied Wall Thickness

The article presents the results of controlled cooling experiments after austenitising a V36 section made of structural steel S480W. The experiments involved variable cooling intensity affecting the cross-section of the test element. The tests aimed to investigate the possibility of modifying the microstructure and uniformly increasing the mechanical properties of steel sections with varied cross-sectional wall thickness in relation to free-air cooling. The research work involved the determination of section-related cooling characteristics identified using various parameters of compressed air blown from nozzles onto selected surfaces of the section. The accelerated cooling tests led to the formation of a fine ferritic-pearlitic microstructure having ferrite grain size D_α restricted within the range of 6.8 μm to 6.5 μm. In addition, the tests resulted in the obtainment of uniform hardness distribution in cross-section, an increase in yield point R_e and tensile strength R_m (restricted within the range of approximately 40 MPa to 60 MPa) while maintaining similar elongation.