Experimental Research and Production of Heavy Gauge DNV 485FDU for Deep Water Trunkline Project

摘要

In this paper, an overview of experimental research and production of 40.5mm DNV 485FDU heavy wall thickness pipeline steel for deep water trunkline project was introduced and analyzed systematically. Alloy design of the steel was introduced. Continuous cooling phase transformation behavior of the steel under deforming condition was investigated. The microstructure of the steel at different cooling rates was observed by the microscope. An optimized cooling process (OCP) after finish rolling was developed in Shouqin Steel Co., Ltd. (SQS). The optimized cooling process guaranteed the steady control of the final bainitic microstructure with optimum polygonal ferrite (PF) for heavy gauge DNV 485FDU plates. The plates produced by this process achieved good tensile strength and excellent lower temperature toughness. The pipes were produced via the JCOE pipe production process and had favorable forming properties and good weldability. Plate mechanical properties successfully met the required final pipe mechanical properties due to the ideal microstructure from the alloy/OCP design.