Effect of prior austenite grain size on the evolution of microstructure and mechanical properties of an intercritically annealed medium manganese steel

Publication date: Available online 27 September 2019Source: Materials Science and Engineering: AAuthor(s): A.K. Chandan, G.K. Bansal, J. Kundu, J. Chakraborty, S. Ghosh ChowdhuryAbstractThis paper presents the influence of prior austenite grain (PAG) size on the evolution of microstructure and mechanical properties in an intercritically annealed medium manganese steel (Fe- 8.1 Mn - 0.3 C- 1.1 Si- 1.5 Al). The hot forged alloy was austenitized at two different temperature-time combination to achieve the PAG size of ∼20 μm (sample 1) and ∼40 μm (sample 2). Both the samples retained a small amount of austenite after the austenitization treatment. The sample 1 with smaller PAG size stabilized a significantly higher amount of austenite (∼54.4 ± 0.6 vol%) after the intercritical annealing treatment than the sample 2 (∼39.3 ± 0.7 vol%). Composition as well as dimension of the austenite films were found to be different in the two samples. Sample 1 displayed a better combination of strength and ductility (1096 ± 30 MPa and 32 ± 4.2%, respectively) as compared to the sample 2 (1026 ± 30 MPa and 22 ± 1.9%, respectively). The superior mechanical properties of sample 1 were ascribed to the cumulative effect of the higher volume fraction and lower stability of retained austenite in sample 1 as compared to the sample 2. Fracture surface investigation revealed that the sample 1 experienced microvoid mediated ductile fracture, whereas ...
Source: Materials Science and Engineering: A - Category: Materials Science Source Type: research