Effect of alloying elements in U78CrV rail on critical cooling rate of pearlite
A critical cooling rate(vc)plays a crucial role in a heat treatment process of U78CrV steel rails,as it significantly impacts an austenite to pearlite transformation.The vc is not a fixed parameter;rather,it varies with a fluctuation of alloying element content.The influence of the major alloying elements(C,Mn,Si,Cr,and V)on the vc of U78CrV steel rails was investigated.Moreover,a dynamic prediction model for vc based on the alloying content of C,Mn,Si,Cr,and V was established.It was found that the vc of U78CrV steel rails ranged between 3 and 6 ℃/s,corresponding to variations in alloying element content.In cases where the specific alloying element content of the steel rails of a batch was unknown,it was advisable to keep the cooling rate below 3 ℃/s.The order of influence of alloying element content on vc was as follows:w(Si)＞w(Mn)＞w(Cr)＞w(V)=w(C).During production,the actual alloy composition of the steel rails was determined,which was subsequently introduced into the predictive model presented to derive the anticipated vc.Cooling was conducted at a rate close to,but not exceeding,the predicted vc.This approach aided in producing heat-treated steel rails with higher performance.
U78CrV steel railalloying elementpearlite transformationcritical cooling rateprediction model
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