Abstract: For NbC_xN_1-x in low-carbon microalloyed steels,x values in the formula are calculated by existing methods.As shown in the calculation results,the x values are mainly influenced by temperature and composition.The x values increase with increasing C content and decreasing N content,as well as decreasing temperature.It is indicated that in a certain range of composition and temperature,the calculation results is in good agreement with experimental data from related references.On the other hand,for the steel with composition over the range,the calculation results should be treated as a reference only.The ranges of temperature and composition are 1050 to 1250℃ and 0.10%C-0.005%N-0.20%Nb to 0.20%C-0.005%N-0.20%Nb,respectively.