溶接用 SH-CCT 図におけるフェライト変態域について : 溶接用 SH-CCT 図の検討(第 2 報)

概要

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F transformation region in SH-CCT diagram for welding for high strength steels was investigated to make use of the dilation curves and A⟶F transformation curves. The starting line of F transformation as measured by the dilatation and the thermal analysis method has departed slightly from the 1% precipitation lines of ferrite. The starting line of F transformation has departed maximum ±10℃ from the 1% precipitation line of ferrite. In the case of slow cooling, F transformation curve was lower than the 1% precipitation line of ferrite. On the other hand, F transfor ma tion curve, in the case of rapid cooling, was higher than the 1% precipitation line of ferrite. When the dilatation curve possesed a two stage expansion process, the growth of ferrite did not cease in the temperature region between the start of secondary contruction and the start of secondary expansion of the dilatation curve during the cooling process, but continued even in this temperature region. For this reason, we considered that no nontransformation region existed between the F and Zw transformation regions in SH-CCT diagram for welding. It was considered that the two stage expansion process of dilatation curve above mentioned was the effects of Cr, Mo and the other elements which were a strong carbide former. Moreover, the F transformation region of SH-CCT diagram for welding was defined.
1970-08-25