Influence of Dynamic Three Point Bending on the Work Hardening Capacity of T105Mn120 Manganese Steel
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JMEPEG https://doi.org/10.1007/s11665-018-3658-2
Influence of Dynamic Three Point Bending on the Work Hardening Capacity of T105Mn120 Manganese Steel V. Bulbuc, B. Pricop
, F. Maxim, M. Popa, N. Cimpoes¸ u, and L.G. Bujoreanu
(Submitted June 23, 2017; in revised form February 28, 2018) The paper analyzes work hardening behavior of T105Mn120 Hadfield steel under dynamic conditions. The specimens were investigated under two states: (a) untreated (as cast) and (b) solution treated to 1100 °C. Dynamic flexural behavior was examined by means of three-point-bending tests performed with a dynamic mechanical analyser (DMA), and structural analysis was done by x-ray diffraction, optical and scanning electron microscopy; DMA tests were performed under two variants: (a) temperature scans, between 2 150 and 400 °C and (b) isothermal strain sweeps, up to 0.15% strain amplitudes. The former emphasized the critical temperatures of thermally induced reversible martensitic transformation and antiferromagnetic– paramagnetic phase transition, while the latter enabled to monitor the storage modulus increase due to the work hardening caused by dynamic bending. Strain sweeps tests revealed the effects of both dynamic bending frequency and number of cycles. The largest work hardening effect, obtained after five strain sweep cycles applied at the frequency of 5 Hz, was associated with the finest distribution of precipitated carbides, observed by differential scanning calorimetry and the formation of slip micro-bands, illustrated on OM micrographs and SEM energy dispersion spectroscopy maps. Keywords
DMA, internal friction, manganese steel, storage modulus, work hardening
1. Introduction Hadfield steel, with approx. 1.2 C and 12 Mn (mass%, as all chemical compositions will be given hereinafter) was invented by Sir Robert Hadfield in 1882, being initially destined to the manufacturing of tramway wheels but, owing to its exceptional hardness and toughness, its destination shortly switched to railway passages and digging equipment (Ref 1). Later, during World War I, it became the main component of armors and shields for warfare protection (Ref 2). This unique austenitic steel combines high tensile stress and ductility with elevated work hardening capacity and excellent abrasive wear resistance (Ref 3). It has an equilibrium structure comprising manganese-alloyed austenite and alloyed cementite, (FeMn)3C, but it becomes fully austenitic after solution treatment (Ref 4), even if it represents the metallic matrix of a composite (Ref 5). When subjected to repeated compression stresses, localized on contact surface, Hadfield steel work hardens, due to the formation of e-hexagonal close-packed martensite, containing mosaic blocks, which contributes to the Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11665-018-3658-2) contains supplementary material, which is available to authorized users. V. Bulbuc, The National Railway Company ‘‘CFR’’ SA, Regional Branch of Passenger Rail Iasi, Str. Piat¸ a Ga˘rii 1,
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