STP1042

    A Newly Developed Ti-Oxide Bearing Steel Having High HAZ Toughness

    Published: Jan 1989


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    Abstract

    A study was carried out on the transformation characteristic of a newly developed Ti-O steel in comparison with that of ordinary steels. The microstructure of the weld heat affected zone (HAZ) in the Ti-O steel is characterized by the formation of intragranular ferrite plate (IFP), or so-called acicular ferrite, which was found to start from titanium sesquioxide (Ti2O3) particles dispersed in the matrix of the steel. The welding thermal cycle simulation test on the Ti-O steel showed that IFP development takes place over a wide range of conditions such as heating temperature and chemical composition. The high stability of Ti2O3 particles at high temperature explains the effect of the former condition. The effect of the latter can be well understood from the distribution of Ti2O3 particles, which is irrelevant to the microsegregation of alloying elements such as manganese and niobium. IFP formation restricts development of ferrite side plate, refines the effective grain size, and improves HAZ toughness. Various experimental results suggested that the Ti2O3 particle has an IFP formation function through the manganese sulfide (MnS) attached on it.

    Keywords:

    high strength alloy steel, low carbon steel, steel for low temperature service, phase transformation, toughness, weldability, inclusion, grain size


    Author Information:

    Yamamoto, K
    Researcher, senior researcher, and executive counsellor, Research and Development Laboratories-II, Nippon Steel Corporation, Kanagawa,

    Matsuda, S
    Senior researcher, Research and Development Laboratories-I, Nippon Steel Corporation, Kanagawa,

    Haze, T
    Researcher, senior researcher, and executive counsellor, Research and Development Laboratories-II, Nippon Steel Corporation, Kanagawa,

    Chijiiwa, R
    Researcher Kimitsu Works, Nippon Steel Corporation, Chiba,

    Mimura, H
    Researcher, senior researcher, and executive counsellor, Research and Development Laboratories-II, Nippon Steel Corporation, Kanagawa,


    Paper ID: STP24586S

    Committee/Subcommittee: A01.13

    DOI: 10.1520/STP24586S


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