Mossbauer and XRD characterization of the phase transformations in a Fe-Mn-Al-C-Mo-Si-Cu as cast alloy during tribology test

Abstract

In present study Fe-29.0Mn-6Al-0.9C-1.8Mo-1.6Si-0.4Cu (%w) alloy was obtained after melted in an induction furnace, and then molded as an ingot. From the as cast ingot it were cut samples for the different characterization measurements. The microstructure of the as-cast sample is of dendritic type and its XRD pattern was refined with the lines of the austenite, with a big volumetric fraction, and the lines of the martensite, with small volumetric fraction. The Mössbauer spectrum of the sample was fitted with a broad singlet which corresponds to disordered austenite. After the tribology test, its XRD pattern was refined with the lines of two austenite phases, one similar to the previous one and other with bigger lattice parameter. The total volumetric fraction of the austenite is smaller than that obtained for sample without wear. It was added the lines of the martensite phase with bigger volumetric fraction than that of the previous sample. The Mössbauer spectrum of the weared sample was fitted with two paramagnetic sites which correspond to the two Fe austenite phases and a hyperfine magnetic field distribution which is associated to the disordered original martensite and the new one which appears in the surface as a consequence of the wear process. These results show that during wear process the original austenite phase is transformed in martensite and in a new austenite phase. The increases of the martensitic phase improves mechanical properties and wear behavior.

Comparative study of the mechanical and tribological properties of a Hadfield and a Fermanal steel

“…This can be interpreted as a consequence of the thermal treatments, which produce martensite in the Fermanal sample, and this phase improves the mechanical properties of steel. The wear test on Fermanal steel increases the martensite fraction, improving its mechanical properties, as reported by Ramos et al [8].…”

“…After the development of Hadfield steels, other alloys based on the steel concept of this austenitic manganese steel with varying compositions followed [7]. One such alloy is the Fe-Mn-Al-C alloy or "Fermanal" steel, which was developed to replace some conventional stainless steels (Ni-Cr steels) [8]. This austenitic steel exhibit a good strain hardening behavior and is considered to be an economic substitutes for conventional austenitic stainless steels because it contains aluminum and manganese instead of chromium and nickel [9,10].…”

“…In the absence of an inert atmosphere, a high solubilizing temperature often produces surface decarburization and leads to a loss of manganese, leading to the formation of α-martensite on the surface layer upon quenching [12]. The increase in the martensite content is good for increasing the mechanical properties of the steel [8].…”

A general perspective of Fe–Mn–Al–C steels

“…It is important to note that in this investigation the precipitation of the κ-carbides was produced by the conventional treatment of quenching + aged, where it was observed that the carbides precipitate along grain boundaries, thus causing brittleness. Another interesting work was performed by Ramos et al (2015) [243] who studied the abrasive wear of a Fe-29.0Mn-6Al-0.9C-1.8Mo-1.6Si-0.4Cu steel in "as cast" condition. In this work, they found that the austenite was transformed into martensite during the wear process.…”

“…Another interesting work was performed by Ramos et al (2015) [243] who studied the abrasive wear of a Fe-29.0Mn-6Al-0.9C-1.8Mo-1.6Si-0.4Cu steel in "as cast" condition. In this work, they found that the austenite was transformed into martensite during the wear process.…”