Numerical - Experimental correlation of microstructures, cooling rates and mechanical properties of AISI 1045 steel during the Jominy end-quench test

摘要

This work addresses the numerical correlation of the factors that may affect the hardenability of AISI 1045 steel submitted to the Jominy end-quench test in three austenitizing temperatures: 20 ℃, 70 ℃ and 120 ℃ above the critical temperature (A_(c3)) according to the CCT diagram (Continuous Cooling Transformation). Thermocouples were placed in the specimens at predefined points to obtain cooling curves during the Jominy end-quench test. Metallographic analysis and the Jominy hardness profiles (using the Rockwell C method) allowed evaluating the hardenability in function of the austenitizing temperatures. Calculation of the percentage of phases presented in the microstructures and Vickers microhardness tests at these phases and micro-constituents were applied to obtain numerical expressions to correlate the phase percentages and hardness profiles according to the cooling rate variations during the test. Subsequently, equations were obtained by regression numerical methods to estimate the amount of phases and micro-constituents (martensite, bainite, pearlite and ferrite) formed during the test, and also to estimate the hardness profile.