Effect of Rolling Technology on Microstructure and Microhardness of Lowcost X80 Pipeline Steel

Simulating rolling was carried out for traditional X80 pipeline steel and lowcost X80 pipeline steel using Gleeble-1500 thermal simulated test machine,the effects of deformation temperature, cooling rate and finish cooling temperature on microstructures and microhardness were studied. The results show that microstructures of the two tested steels were acicular ferrite, quasi-polygonal ferrite and granular bainite, and their microhardness had little difference. With the decrease of the deformation temperature and final cooling temperature, the increase of the cooling rate, the microstructure of lowcost X80 pipeline steel was refined and M/A island changed from rods to dots with smaller size gradually, and the microhardness of lowcost X80 pipeline steel had a little fluctuation.