Effect of tip velocity on weld solidification process of hot-work tool steel

Abstract

In order to clarify the effect of tip velocity on the weld solidification process of hot-work tool steel (SKD61) during the welding, the information about microstructure evolution was obtained by the combination of liquid tin quenching and Time Resolved X-ray Diffraction (TRXRD) technique using intense synchrotron radiation. From the experimental results, it. was found that, the solidification mode was changed from. FA mode (L→ L-δ→L + δ-y → L-γ→ y) to A mode (L → L + y → y ) at high tip velocity. Moreover, the effect of tip velocity on the microstructure selection during solidification between the primary ò - ferrite and the primary y - austenite was theoretically proven by the KGT model. Therefore, it was understood that the solidification cracking susceptibility of hot-work tool steel (SKD61) weld metal was increased due to the δ to y transition of the primary phase.