| An attempt has been made to investigate the effects of alloying elements on the mechanical property of structural steels by optimizing the thermodynamic parameters, calculating the chemical driving forces and calculating the nucleation and growth rates in a wide temperature and composition ranges for a carbide, which is thought to give a great effect on the mechanical behavior of steels. For a structural steel including 3 Ni, 1.5 Cr, 0.4 Mo, 0.2 Mn, 0.02 V and 0.17 C by weight percent, calculation of nucleation rates for various carbides predicted that cementite, M_(23)C_6 and M_7C₃ can precipitate in an early stage of tempering at. 923K. Calculation shows that the addition of V up to about 0.1 wt% abruptly decreases the growth rate of M_7C₃ while addition of V more than about 0.1 wt% increases the growth rate of M_7C₃, again. Thus, to get fine distributions of M_7C₃ in this structural steel, it is recommanded from this calculation, that V should be included not more than 0.1 wt%. |
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