Effect of Ball to Powder Ratios on the Phase Transformation of Austenite and Ferrite During Ball Milling of SAF-2507 Super Duplex Stainless Steel Powders

Abstract

Nanostructured SAF-2507 super duplex stainless steel powders were prepared in a Retsch PM-100 planetary ball mill for 20 h at 5:1 and 10:1 ball to powder ratios, respectively. In both the BPR cases, the crystallite sizes reduced, and lattice strain increased with the milling time. The crystallite size, lattice strain, and lattice parameter were determined using the Williamson-Hall equation and the Nelson–Riley technique, respectively. The XRD and SEM results complement the HRTEM data. When the outcomes of 5:1 and 10:1 BPR samples are compared, it is found that the 10:1 BPR works better than the ball milling done with 5:1 BPR in terms of reducing crystallite size, increasing lattice strain, and favoring the austenite phase. The purpose of this work is to determine the stable austenitic phase that is responsible for the production of the dual phase alloy and to optimize the duration of the ball milling process. The current study also discussed the potential effects of an extended milling time on the phases and morphology of SAF-2507 powders. Higher milling times have been shown to support the stabilization of the ferritic phase. © 2024 Elsevier B.V., All rights reserved.