The Effects of Quenching Temperature on Mechanical Strength in Micro Alloyed Steel with Boron

Abstract

Materials and MethodsTen samples with dimensions of 300.0x35.0mm were cut from a sheet with a thickness of 7.5mm in the longitudinal direction of rolling. Afterward, five specimens were quenched in an electric furnace at 850 and five at 1050 °C for 30 minutes. The tensile test was carried out in a universal hydraulic test machine with a capacity of 500kN and strain gauge with measurable deformation of 50mm and pulled with 1mm per minute constant strain speed according API SPEC 5CT-12 standard. After tensile tests the samples were prepared following conventional metallographic methods. The microstructures were observed by Scanning Electronic Microscope (SEM) after attack with Lepera reagent. The Vickers hardness with load of 10kgf were obtained in all specimens considering the ISO 6507-1 standard. Results represent the average of five measurements in each test piece, under all conditions of quenching. Results Figures 1a & 1b, show the martensite laths (blue color) and auto-tempering martensite (brown color) after quenching at 850 and at 1050 °C. Figures 1a & 1b, show the martensite laths (blue color) and auto-tempering martensite (brown color) after quenching at 850 and at 1050 °C.