Austenite decomposition in medium carbon microalloyed steels: Mechanism, structure and properties

Fadel, Abdunnaser

doi:10.2298/bg20130514fadel

Cited by 1 publication

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References 117 publications

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“…Results of previous research indicate that the fine interlocked structure of acicular ferrite has a beneficial effect on the toughness of the medium carbon microalloyed steels [9][10][11]. Vanadium-nitride particles, in addition to their role in precipitation hardening, are found to be highly effective as a preferential place for intragranular nucleation of acicular ferrite [12][13][14][15]. In this way, the addition of vanadium together with high nitrogen levels in the steel favors the formation of acicular ferrite at the expense of bainite [15] and thus acts in the direction of fracture toughness improvement.…”

Section: Introductionmentioning

confidence: 98%

Structure and Strength of Isothermally Heat-Treated Medium Carbon Ti-V Microalloyed Steel

Dikić

Glišić

Fadel

et al. 2021

Metals

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Isothermal transformation characteristics of a medium carbon Ti-V microalloyed steel were investigated using light microscopy, scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), and by uniaxial compressive testing. Samples austenitized on 1100 °C were isothermally treated in the range from 350 to 600 °C and subsequently water quenched. The final microstructure of the samples held at 350 °C consisted of bainitic sheaves and had compressive yield strength, approximately from 1000 MPa, which is attributed to high dislocation density of low bainite. At 400 and 450 °C, acicular ferrite became prevalent in the microstructure. It was also formed by a displacive mechanism, but the dislocation density was lower, leading to a decrease of compressive yield strength to approximately 700 MPa. The microstructure after the heat treatment at 500 °C consisted of coarse non-polygonal ferrite grains separated by pearlite colonies, principally dislocation free grains, so that the compressive YS reached a minimum value of about 700 MPa. The microstructure of the samples heat-treated at 550 and 600 °C consisted of pearlite and both grain boundary and intragranular ferrite, alongside with some martensite. After 600 s, austenite became stable and transformed to martensite after water quenching. Therefore, the presence of martensite increased the compressive YS to approx. 800 MPa.

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