Effect of Grain Refining on Properties of Super Austenitic Stainless Steel

Abstract

The goal of this study was to evaluate the industrial performance of cast high-alloy superaustenitic 19Cr17Ni-6Mo stainless steel by refining the as-cast structure. A grain-refined, as-cast structure was achieved by the in situ inoculation with titanium nitrides (TiN) co-precipitated on previously formed spinel (MgAl2O4) inclusions, thus promoting heterogeneous nucleation of austenite during solidification. A homogenization heat treatment of the casting did not provide significant changes of the as-cast grain macrostructure in either the base or grain-refined steels. However, it was found that a combination of inoculation with heat treatment is an effective way of reducing interdendritic segregation. The industrial performance which includes the mechanical properties, corrosion resistance, and machinability was evaluated in the heattreated condition for both base and inoculated steels. Tensile testing revealed improvements in ultimate tensile strength, ductility, and yield strength of the inoculated steel. The room-temperature impact properties exhibited a slight decrease in average impact energy but showed reduced variability in the inoculated steel compared to the base steel. The machining results showed that the inoculated steel had a slight improvement in machinability. The inoculated steel exhibited a lower corrosion rate but showed an increase in mass loss due to pitting. The changes in steel performance were linked to microstructure and nonmetallic inclusion families obtained by automated ASPEX SEM/EDX analysis.

Department(s)

Materials Science and Engineering

Research Center/Lab(s)

Peaslee Steel Manufacturing Research Center

Keywords and Phrases

Corrosion resistance; Grain refinement; Machinability; Mechanical properties; Segregation; Superaustenitic stainless steel

International Standard Serial Number (ISSN)

1059-9495; 1544-1024

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2019 Springer Verlag, All rights reserved.

Publication Date

01 Mar 2019

Link to Full Text

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