STP672: Control of Microstructure by the Processing Parameters and Chemistry in the Arctic Line Pipe Steels

    Ouchi, C
    Research metallurgist, senior researcher, and manager, Technical Research Center, Nippon Kokan K. K., Kawasaki,

    Tanaka, J
    Research metallurgist, senior researcher, and manager, Technical Research Center, Nippon Kokan K. K., Kawasaki,

    Kozasu, I
    Research metallurgist, senior researcher, and manager, Technical Research Center, Nippon Kokan K. K., Kawasaki,

    Tsukada, K
    Research metallurgist, Fukuyama Research Laboratory, Nippon Kokan K. K., Fukuyama,

    Pages: 21    Published: Jan 1979


    Abstract

    With the increasing demand for the higher strength and superior low-temperature toughness in arctic line pipe steels, new processings as well as the new kinds of steels have been developed. Controlled rolling, accelerated cooling after controlled rolling, and heat treatment after pipe forming are included in these processes. The characteristic features of the various microstructures obtained by each processing and their relationships with the mechanical properties are described. The recent development of controlled rolling practice tends to control the wider range of rolling temperature and to utilize the various strengthening mechanisms, accompanied with improvement of toughness. The accelerated cooling after controlled rolling, developed as a new process in plate mill, gives rise to the duplex structure composed of very fine ferrite and bainite. This process enables one to decrease carbon content or alloying elements and to improve weldability of line pipe steels. The microstructural features of heat treatment after piping and welding are described, emphasizing those of weldments.

    Keywords:

    steels, microstructure, line pipe steel, controlled rolling, accelerated cooling, heat treatment, mechanical properties, weldability, stress corrosion, high-strength steel


    Paper ID: STP36866S

    Committee/Subcommittee: E04.05

    DOI: 10.1520/STP36866S


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