The processes of reheating in the temperature range (T reheat / from 950 to 1250 ı C with the holding time (t hold / from 600 to 3600 s on the material known as high-strength low-alloy (HSLA) steel were investigated. The abnormal grain growth caused by the dissolution of Nb(C x ,N y / particles was observed after T reheat reached 1150 ı C. The influence of T reheat on average austenite grain size (AGS) was stronger than that of t hold . Two different models were applied for the description of average AGS on T reheat and t hold .