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 Dα 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 Re and tensile strength Rm (restricted within the range of approximately 40 MPa to 60 MPa) while maintaining similar elongation.