Study on Hot Rolling Process of Steel Plate for X80 Grade Pipeline with Large Diameter and Thick Wall Specification
Based on the design of alloying composition system of hot rolled X80 grade pipeline steel plate,the pa-per studies the hot rolling process of the X80 grade pipeline steel plate by means of the melting and rolling platform of the pilot plant.The results show that when the reduction ratio is over 26％and the holding time equals to 60 s for the X80 grade pipeline steel plate,the austenite grains recrystallization is initiated and apparent refined and recrystallized microstructure is obtained;when the coiling temperature is 400 ℃,the refined martensite and austenite islands are dis-persed in the matrix with excellent corresponding DWTT toughness.With a comprehensive consideration on the alloying characteristics of the chemical composition for X80 grade pipeline steel,the ideal control level of the yield strength,yield to tensile strength ratio,Charpy impact energy value and percentage of DWTT shearing area for the plate coil,the coiling temperature of(400±35)℃ is selected for the industrial trial production.
Pipeline steelHot rollingMicrostructurePrimary austeniteCoiling temperatureFinish rolling tem-perature
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