| Title |
Research Paper - Transformations - : Solidification and δ- ferrite Formation of High Alloyed Austenitic Stainless Steel |
| Authors |
김선구(Sun K . Kim); 김종완(Jong W . Kim); 심상대(Sang D . Shim); 이연용(Yun Y . Lee) |
| Abstract |
In order to investigate the cause of increase in δ-ferrite content from 9.1 to 14.3% with increasing the Cr_(eq)/Ni_(eq) ratio from 1.48 to 1.71 in type 309S stainless steel, the solidification path and transformation of δ-ferrite to austenite were studied by interrupted quenching experiment of unidirectional solidification.δ-ferrite in 309S stainless steel precipitates with primary dendrite irrespective of Cr_(eq)/Ni_(eq) ratio but the formation mechanism of austenite is different depending on Cr_(eq)/Ni_(eq) ratio. Stainless steel at 1.48 of Cr_(eq)/Ni_(eq) starts to form austenite from liquid remained at interdendrites at 1397℃ and completes solidification at 1357℃, but stainless steel at above 1.48 of Cr_(eq)/Ni_(eq) forms austenite by peritectic reaction before solidification. As the Cr_(eq)/Ni_(eq) ratio increased from 1.48 to 1.71, maximum δ-ferrite content formed before austenite formation increased from 54 to 75% and austenitic formation temperature decreased from 1390 to 1383℃. |