On the origin of subgrain boundaries during conventional solidification of austenitic stainless steels

20th Chemnitz Seminar on Materials Engineering - 20. Werkstofftechnisches Kolloquium

Rahimi, R.^1 ; Biermann, H.^2 ; Volkova, O.^1 ; Mola, J.^1

Institute of Iron and Steel Technology, Technische Universität Bergakademie Freiberg, Leipziger Str. 34, Freiberg

09599, Germany^1

Institute of Materials Engineering, Technische Universität Bergakademie Freiberg, Gustav-Zeuner-Straße 5, Freiberg

09599, Germany^2

关键词: Austenite formation;    Conventional casting;    Dynamic scanning;    Low angle grain boundaries;    Peritectic reaction;    Subgrain boundaries;    Subgrain formation;    Thermodynamic calculations;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/373/1/012005/pdf
DOI  :  10.1088/1757-899X/373/1/012005

来源: IOP

【 摘 要 】

The origin of subgrain formation during conventional casting and solidification of stainless steels was studied using two austenitic stainless steels with 0 and 4 mass-% Al. Whereas the Al-free alloy showed no subgrain formation, the Al-added alloy developed a high density of subgrains separated by low-angle grain boundaries. The occurrence of subgrains in the Al-added alloy was justified by its ferritic mode of solidification as predicted by thermodynamic calculations and confirmed by dynamic scanning calorimetry measurements. The subgrains might be a consequence of the plastic deformation of soft primary ferrite dendrites by the fluid flow and their subsequent inheritance by the austenite. Alternatively, they might have been induced during the austenite formation from delta ferrite, most likely via a peritectic reaction. The absence of subgrains in the Al-free alloy was justified by its austenitic mode of solidification.