The austenite grain growth behaviour of microalloyed Al–V–N and Al–V–Ti–N steels has been studied. Estimations of austenite grain size for Al–V–N steels by several different grain growth inhibition models demonstrated that the best match to experimental results can be obtained from Gladman and Rios equations and it is AlN that controls the austenite grain size. The experimental and calculated results indicated that the drag force of plate-shaped AlN particles probably depends on their orientation and austenitising temperature. A modified Gladman model, which considers the effects of complex arrays of different types of particles on the stabilized austenite grain size, can be used to predict the austenite grain size and particle size for an Al–V–Ti–N steel when the combined effect of AlN and TiN is considered.