Effect of Reheating Temperature on Austenite Grain Size and Solid Solution of Second Phase Particles of the Pipeline Steel Slab

Effect of reheating temperature on austenite grain size and solid solution of second phase particles of X70 pipeline steel slab was researched by using optical microscope. The results show that the microstructures are homogeneous and the grain size increases slowly with the reheating temperature increases from 1120°C to 1180°C. However, the abnormal growth phenomenon can be observed in the specimens reheated at 1210°C. The reason is that all second phase particles except TiN, dissolves in austenite at 1210°C. The temperature range from 1140°C to 1180°C is suitable for reheating X70 steel slab. (paper)