The growth behavior of austenite grain of secondary hardening ultra-high strength steel AF1410 (% : 0.165C

14.10Co

9.83Ni

1.92Cr

1.05Mo) heating at 800 ~ 1200 °C for 5 - 180 min has been studied. Results show that with increasing heating temperature and holding time the average austenite grain size of steel AF1410 increases

and the austenite grains coarsen seriously at temperature more than 1100

℃

at different heating temperature; the relation between average austenite grain size of steel and holding time corresponds to Beck equation ； the math model for austenite grain growth of steel AF1410 has been established

with heating at 800〜1200 °C the average activation energy for austenite grain growth of the steel is 220.2 kJ/mol

and the relation between its average austenite grain size and heating temperature conforms to Arrhenius-type equation.