溶接凝固時におけるミクロ偏析の数値解析法による検討

二相ステンレス鋼の溶接割れ感受性に関する研究(第4報)

抄録

A two dimensional solidification modelling of cellular dendritic growth was proposed in order to study the weld solidification phenomena of stainless steels. The modelling was made based on the quenched solidification microstructures. Fraction solid with temperature and segregations of the solutes within the cellular dendrite were calculated by means of finite difference method. Main conclusions obtained are as follows:
(1) In this modelling, fraction solid was increased very rapidly just below liquidus temperature, and thus the temperature where the beginning of solid bridge was formed was very close to the liquidus temperature. Therefore, the temperature range where the residual liquid was confined by the sllid bridges was very long.
(2) These behaviors mentioned in (I) were fitted well with the actual solidification microstructures revealed by liquid-tin quenching. On the other hand, the parabolic growth model where solid-liquid interface advances in proportion to square root of time did not fit with the actual microstructure.
(3) Distributions of Ni and Cr in cellular dendrite calculated corresponded well to the EPMA results.
(4) It was concluded that the two dimensional modelling proposed in this reoprt was very useful to understand the weld solidification phenomena.