Effects of Rare Earths on Austenite Grain Growth Behavior in X80 Pipeline Steel

Accorded with the criteria the X80 pipeline steels with RE additions have been prepared with a vacuum induction furnace. The effect of rare earths (RE) on austenite grain growth behavior in pipeline steel has been discussed in this work. After hot rolled, the effect of RE on austenite grain growth behavior have been studied by the thermal simulator, scanning electron microscopy and metallographic microscope. The results indicate that RE additions inhibit the abnormal growth of austenite grain, trace RE could significantly influence the austenite grain growth behavior, and obtain fine grain size in X80 pipeline steel. For instance, the activation energy of grain growth reduced from 475 kJ/mol to 425 kJ/mol with addition of 0.0220 wt.% RE according with no deliberate RE additions, but the grain growth index increased from 3.5 to 4.5.