Properties and homogeneity of 550-MPa grade TMCP steel for ship hull

Yi Nie~(1,2)),Cheng-jia Shang~(1)),Xin Song~(1)),Yang You~(1)),Chuang Li~(1)),and Xin-lai He~(1)) 1) School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China 2) Department of Physics and Chemistry,Henan Polytechnic University,Jiaozuo 454000,China

摘 要：<正>Ultra low carbon steels by the thermal mechanical control process（TMCP） with less Ni,Cr,and Mo contents have been developed for 550 MPa grade heavy gauge ship hulls and offshore structures.The relationships among microstructures,process,and properties of the studied steel have been investigated.A series of accurate control technologies have been developed for this kind of steel.Cu microalloying and TMCP+relaxation precipitation control（RPC）+accelerated cooling process were employed to optimize the mechanical properties and ensure the homogeneity of the 80-mm thick plate.The microstructures of thin plates slightly changed from surface to center,but the micro-structures of the heavy gauge plate（80 mm） changed notably.Adopting the simple composition,it can meet the requirement of thin plates by adopting a few microalloys.As for thick plates（80 mm）,a little higher Cu and Ni contents should be adopted.These steels can meet the needs without tempering.By these ways,the properties of the steels can be optimized,and the cost can be decreased notably.

关键词：