Weld Cracking in Duplex Stainless Steel (Report II) : Modelling of Cellular Dendritic Growth during Weld Solidification(Materials, Metallurgy & Weldability)

概要

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A two dimensional solidification modelling of cellular dendritic growth was proposed in order to study the weld solidification phenomena of stainless steels in detail. The modelling was made based on the quenched solidification microstructures. Fraction solid vs. 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 increases very rapidly near liquidus temperature, and thus the temperature where the beginning of solid bridge is formed is very close to the liquidus temperature. (2) Therefore, the temperature zone where residual liquid is confined by the solid bridges is very long. (3) These behaviors mentioned in (1) and (2) fits well with the actual solidification microstructures. On the other hand, parabolic growth model where solid-liquid interface advances in proportion to square root of time does not fit with the actual microstructure. (4) Distributions of Ni and Cr in cellular dendrite calculated corresponded well to the EPMA analysis. It was concluded that the two dimensional modelling is very useful to understand the weld solidification phenomena compared with conventional models.
大阪大学の論文