Influência do perfil longitudinal de temperatura na variação das propriedades mecânicas de chapas grossas para aplicação em tubos, processadas por resfriamento acelerado

Abstract

The production of heavy plates for pipe application was boosted from the 1960s by the development of the controlled rolling process, TMCR (Thermomechanical controlled rolling) and later by the use of accelerated in-line cooling after controlled rolling, giving rise to the process TMCP (Thermo-mechanical controlled process), which is currently the most employed. In industrial scale production, one of the biggest challenges is related to the losses that occur along the process, one of them being the regions near the ends that are discarded due to the variations in properties in such regions. This work focused on evaluating the influence of the longitudinal temperature profile on the variation of the mechanical properties and microstructure of plates for oil and gas pipelines, produced by accelerated cooling. As such, the discarded regions close to the plate ends were analyzed and compared with the middle of the plates in terms of mechanical properties and microstructure. Additionally, simulation by dilatometry was done in order to elucidate the observed behavior. The results indicated that there are indeed differences in mechanical properties and microstructure in these regions in relation to the middle, mainly influenced by the temperature profile, but all of them are within specifications, indicating that the metallic yield of these materials can be optimized.