Study on Austenite Grain Growth Behaviour of New Pipeline Steel for Deep Sea

The austenite grain growth behaviour of new pipeline steel for deep sea was researched by using optical microscope. The results show that the microstructures are homogeneous and the grain size increases slowly while the soaking temperature increases from 1120°C to 1180°C. However, the abnormal growth phenomenon can be observed in the specimens reheated at 1210°C. The austenite grain growth behaviour can be described by following equations: lnD = 7.7738- 6242/T (1120°C< T< 1180°C) and lnD = 51.2948-69510/T (1180°C