Thermodynamic models were employed to determine the solubility product of aluminum nitride in steels containing the solid solution elements of Mn, Ni, Cr, and Mo. Specific solubility product expressions were developed and compared with previous results. Overall, good agreement was found, which showed the reliability of the calculation results. The effect of the solid solution elements of Mn, Ni, Cr, or Mo on the solubility products of aluminum nitride in steels was minimal. The final deduced solubility products in austenite and ferrite are given as follows. \({\text{log}}{{}{}^{\gamma }K}_{{\text{AlN}}}=4.21-\frac{10863}{T}+\left(0.004+\frac{82.6}{T}\right){\left[\mathrm{wt \, pct \, Mn}\right]}^{\gamma }+\left(-0.004+\frac{52.5}{T}\right){\left[\mathrm{wt \, pct \, Ni}\right]}^{\gamma }+\left(-0.006+\frac{139.1}{T}\right){\left[\mathrm{wt \, pct \, Cr}\right]}^{\gamma }+\left(-0.007+\frac{38.1}{T}\right){\left[\mathrm{wt \, pct \, Mo}\right]}^{\gamma }\) \({\text{log}}{{}{}^{\alpha }K}_{{\text{AlN}}}=5.46-\frac{12937}{T}+\left(-0.007+\frac{40.6}{T}\right){\left[\mathrm{wt \, pct \, Mn}\right]}^{\alpha }+\left(0.002+\frac{9.4}{T}\right){\left[\mathrm{wt \, pct \, Ni}\right]}^{\alpha }+\left(-0.130+\frac{248.7}{T}\right){\left[\mathrm{wt \, pct \, Cr}\right]}^{\alpha }+\left(0.072-\frac{175.0}{T}\right){\left[\mathrm{wt \, pct \, Mo}\right]}^{\alpha }\)
