Abstract
The aim of this study is to evaluate an effect of impurity elements on solidification cracking susceptibility of a high manganese austenitic steel for cryogenic use. An effect of phosphorus and sulfur was investigated by transverse-type Varestraint test. Increase in an amount of phosphorus enhanced the solidification cracking susceptibility and it was additionally induced the ductility-dip cracking on the Varestraint test. On the other hand, increase in an amount of sulfur didn’t enhance the solidification cracking susceptibility. Quenched microstructure around solid and liquid interface was analyzed by EBSD and EPMA. According to the results of analyses, the solidification mode of high manganese austenitic steel was fully austenite phase and it was assumed that MnS is forming during solidification.
A numerical analysis considered a formation of MnS during welding solidification was carried out in order to quantitatively clarify the effect of phosphorus and sulfur on the susceptibility. According to the result, solidification completion temperature decreases with increasing the phosphorus content. On the other hands, increasing the sulfur content has an insignificant effect on the solidification completion temperature because of MnS formation. Thus, it can be considered that effect of sulfur for solidification cracking might be much smaller than the phosphorus in the high manganese steel.
