Extensive studies to develop high strength linepipes with higher deformability have been conducted. As two-phase microstructure consisted of harder and softer phases are essential to obtain larger deformability, the optimum microstructural characteristics in terms of deformability were investigated by analytical methods that can simulate microscopic behavior of the two-phase steels. The harder and higher volume the harder phases becomes, the larger the work hardenability of two-phase steels becomes. Based on the analytical results, two types of high deformability linepipes which have ferrite-bainite and bainite-martensite (MA) microstructures have been developed. The ferrite-bainite type material has been produced by applying ordinary TMCP (thermomechanical control process) made up with CR (controlled rolling) and AcC (accelerated cooling). In the accelerated cooling stage, lowering cooling finishing temperature has significant effect of increasing work hardenability. The material with bainite-MA microstructure has been produced by applying a new type of TMCP composed with CR, AcC and On-line tempering. Those materials show sufficient strength and deformability for high strength linepipes being able to be used in long distance pipelines crossing the area where large movements of ground could be expected.
Development of high strength linepipes with excellent deformability
Entwicklung von hochfesten Leitungsrohren mit ausgezeichneter Verformbarkeit
2005
11 Seiten, 17 Bilder, 12 Tabellen, 14 Quellen
Conference paper
Storage medium
English
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