In situ observations of continuous cooling transformations in low alloy steels

Pickering, Ed; Collins, J.F.; Stark, Andreas; Connor, Leigh D.; Kiely, A. A.; Stone, H.J.

doi:10.1016/j.matchar.2020.110355

Cited by 9 publications

(4 citation statements)

References 43 publications

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“…The exception, of course, is pearlite, where the carbon-enriched austenite decomposes into cementite simultaneously with ferrite. Carbon partitioning predominantly occurs during transformations to ferrite and bainite as was previously observed [44]. Of course, due to the empirical nature of the model, a fraction of this behaviour may be inadvertently considered within the predictions.…”

Section: Modelling Carbon Partitioningmentioning

confidence: 71%

A Rapid, Open-Source CCT Predictor for Low-Alloy Steels, and Its Application to Compositionally Heterogeneous Material

Collins

Piemonte

Taylor

et al. 2023

Metals

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The ability to predict transformation behaviour during steel processing, such as primary heat treatments or welding, is extremely beneficial for tailoring microstructures and properties to a desired application. In this work, a model for predicting the continuous cooling transformation (CCT) behaviour of low-alloy steels is developed, using semi-empirical expressions for isothermal transformation behaviour. Coupling these expressions with Scheil’s additivity rule for converting isothermal to non-isothermal behaviour, continuous cooling behaviour can be predicted. The proposed model adds novel modifications to the Li model in order to improve CCT predictions through the addition of a carbon-partitioning model, thermodynamic boundary conditions, and a Koistinen–Marburger expression for martensitic behaviour. These modifications expanded predictions to include characteristic CCT behaviour, such as transformation suppression, and an estimation of the final constituent fractions. The proposed model has been shown to improve CCT predictions for EN3B, EN8, and SA-540 B24 steels by better reflecting experimental measurements. The proposed model was also adapted into a more complex simulation that considers the chemical heterogeneity of the examined SA-540 material, showing a further improvement to CCT predictions and demonstrating the versatility of the model. The model is rapid and open source.

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Section: Modelling Carbon Partitioningmentioning

confidence: 71%

A Rapid, Open-Source CCT Predictor for Low-Alloy Steels, and Its Application to Compositionally Heterogeneous Material

Collins

Piemonte

Taylor

et al. 2023

Metals

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“…[ 10 ] Using this dilatometer together with in situ synchrotron X‐ray diffraction, the CCT behavior of two low‐alloy vessel steels was investigated across a range of cooling rates following austenitization. [ 11 ] This study revealed a good agreement in transformation start temperatures between the two techniques and helped to correct the length change signal from dilatometer for ferrite phase quantification, thereby avoiding overestimation. For the first time, an in situ synchrotron experiment using this dilatometer was performed during the solidification of Mg–4Y–3Nd alloy to determine the solidification sequence of the phases and to correlate them with the thermodynamic simulations.…”

Section: Introductionmentioning

confidence: 74%

A Unique Quenching and Deformation Dilatometer for Combined In Situ Neutron Diffraction Analysis of Engineering Materials

et al. 2021

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“…Based on the way of the embrittlement occurrence, the transcrystalline or intercrystalline rupture mechanism can be observed in relation to the fracture surface. In comparison with the transcrystalline fission rupture, the fractures created by intercrystalline ductile rupture belong to the group of low-energy fractures where the less energy is required [ 9 , 10 , 11 , 12 ]. The formation of such fractures means that the conditions for the ductile rupture were kept only for narrow zones which are adjacent to the grain boundaries.…”

Section: Introductionmentioning

confidence: 99%

Fracture Analysis of High-Strength Screw for Highway Construction

Dubec

Kováčiková²,

Krmela³

et al. 2021

Materials

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High-strength screws represent one of the main joining or fastening components which are commonly used in the process of installation of frame constructions for information boards or signposts, relating to the traffic roads. The control of the production process may not always be a sufficient method for ensuring road safety. The backward investigation and control of the screw material processing seems to be the one of the most important procedures when there is the occurrence of any failure during the operation of the screw. This paper is mainly focused on the analysis of the failure of the high-strength screw of 10.9 grade with M diameter of 27 × 3 and a shank length of 64 mm. The mentioned and investigated screw was used as a fastener in a highway frame construction. In the paper, there is mainly the analysis of the material for a broken screw in terms of the material micropurity, the material microstructure, the surface treatment as well as chemical composition. The evaluation was based on investigation by optical microscopy, scanning electron microscopy and energy dispersive spectroscopy. Important knowledge and results were also obtained due to information on micromorphology and material contrast of the fracture surface resulting from fractographic analysis, using the method of scanning electron microscopy. In the case of the production of the high-strength screws, the tempering stands for the decisive or crucial process of heat treatment because the given process can ensure a decrease in hardness, while the required ductile properties of the material are kept and this is also reflected in the increase of strength and micromorphology of the fracture surface. From the aspect of micropurity, inclusions of critical size or distribution were not identified in the material, referring to Czech standard ČSN ISO 4967 (420471). The microstructure corresponds to tempered martensite, but the fracture surface of the broken screw was based on an intercrystalline micromechanism, which is undesirable for the given type of component. Combined with the measurement of the HV1 (Vickers hardness at a load of 1 kg) from the edge to the central area of the screw, the analysis revealed the significant drawbacks in the heat treatment of the high-strength screw.

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In situ observations of continuous cooling transformations in low alloy steels

Cited by 9 publications

References 43 publications

A Rapid, Open-Source CCT Predictor for Low-Alloy Steels, and Its Application to Compositionally Heterogeneous Material

A Rapid, Open-Source CCT Predictor for Low-Alloy Steels, and Its Application to Compositionally Heterogeneous Material

A Unique Quenching and Deformation Dilatometer for Combined In Situ Neutron Diffraction Analysis of Engineering Materials

Fracture Analysis of High-Strength Screw for Highway Construction

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