混粒に関する研究 (II) : 混粒の発生原因について(その 1)

概要

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By the systematic experiments and some theoretical considerations from the view point of grain-growth characteristics of austenite, causes of formation of duplex-grain structures in steels were made clear, and some suggestions were given in relation to the prevention of such structures. Results of these investigations are summarized as follows : (1) "Uniform duplex-grains" appear in the stage of abrupt coarsening of austenite resulting from the dissolution of grain-growth inhibitors into it. (2) "Non-uniform duplex-grains" are due to the primary segregation of grain-growth inhibitors leading to the non-uniform distribution of initial austenite grains on heating through the critical point. (3) Grain-growth inhibitors are predominantly AIN in Al-treated steels, and the relation between the amount of AIN and its degree of segregation determines whether these steels have "uniform duplex-grains" or "non-uniform duplex-grains". (4) For the prevention of "duplex-grains", it is necessary to reduce the primary segregation as little as possible and to preserve the suitable amount of AIN in steels. (5) In addition, it is indicated that "uniform duplex-grains" appear also in the stage of grain-growth after recrystallization of hot-worked steels and "non-uniform duplex-grains" appear also in hyper-eutectoid steels resulting from the primary segregation of carbides.
社団法人日本鉄鋼協会の論文
1958-04-01