Abstract
In order to verify the validity of the developed numerical model to predict the solidification microstructure of austenitic stainless steel weld metal proposed in the previous report, spatially resolved X-ray diffraction measurements using synchrotron radiation have been carried out for Fe-20Cr-11.5Ni and Fe-20Cr-12.7Ni weld metals, quenched in liquid tin. X-ray diffraction analysis of Fe-20Cr-11.5Ni quenched weld metal, solidifying in FA mode (L→L +δ→L +δ+γ→δ+γ), showed that the leading γ phase crystallized in a eutectic growth mode down to a temperature drop of 6 K from the initiation of solidification. Also, from X-ray diffraction analysis of Fe-20Cr-12.7Ni quenched weld metal, which solidified in AF mode (L→L +γ→L +γ+δ→γ+δ), it was found that the leading δ phase crystallized in a eutectic growth mode within the temperature drop range between 18 and 24 K from the initiation of solidification. The crystallization temperatures predicted by the developed numerical model for leading γ and δ phases in Fe-20Cr-11.5Ni and Fe-20Cr-12.7Ni weld metals agreed with experimental data. These agreements support the validity of the developed numerical model. Furthermore, time-resolved in-situ observation of welding solidification process using synchrotron radiation have been carried out for Fe-20Cr-12.5Ni and Fe-20Cr-11.4Ni weld metals, it was found that γ and δ phase crystallized down to a temperature drop within about 47 K and 55 K from the initiation of solidification respectively. These results also coincided with the calculated results for Fe-20Cr-12.5Ni and Fe-20Cr-11.4Ni weld metal using the developed numerical model.
