Segregations in Steels during Heat Treatment – A Consideration along the Process Chain

Hunkel, M.

doi:10.1515/htm-2020-0006

Cited by 12 publications

(4 citation statements)

References 65 publications

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“…These bands typically align along the direction of hot rolling, a characteristic observed in both laminated carbon steels and stainless steels. 16,17 The emergence of metallurgical segregation bands is generally considered undesirable, as they can impair machinability, induce distortion during heat treatments, and alter mechanical properties. 18,19 For all types of steels, the microstructure is of paramount importance as it directly influences the mechanical properties.…”

Section: Microstructural Characterisation and Analysismentioning

confidence: 99%

Evaluation of corrosion behaviour and susceptibility to hydrogen-induced cracking in high-strength low-alloy X70 steels under sour gas conditions

Quiñones,

Condori,

Apaza-Apaza

et al. 2024

Corrosion Engineering, Science and Technology: The Internationa

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High-strength low-alloy (HSLA) steels find extensive usage in the oil industry for manufacturing pipes due to their requirement for materials with high mechanical and corrosion resistance. Among these steels, the HSLA X70 steels are particularly of great interest to the petroleum industry because of its high mechanical resistance, ductility and weldability. In this study, it was aimed to assess the corrosion behaviour of HSLA API X70 pipelines using electrochemical impedance spectroscopy (EIS) technique and evaluate its resistance to hydrogen-induced cracking (HIC). The analyses were conducted in non-sour and sour media, as per NACE TM0284 standard. Microstructural characterisations of polished and corroded samples were also conducted using scanning electron microscopy (SEM) and optical microscopy (OM). The results indicate that the resistance to HIC in API 5L X70 steel is compromised when exposed to surface corrosion in sour gas media. This susceptibility may be attributed to the presence of microconstituents MnS and M/A along the grain boundaries, which were found in the crack trajectory. The identified microstructural features are deemed to exert a significant influence on the propagation of cracks and the consequent susceptibility to HIC. Moreover, the EIS tests revealed the lowest corrosion resistance when exposed to H2S media, as MnS inclusions accelerate the active regions in the matrix, consequently leading to the formation of a plethora of corrosion products and the dissolution of iron.

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Section: Microstructural Characterisation and Analysismentioning

confidence: 99%

Evaluation of corrosion behaviour and susceptibility to hydrogen-induced cracking in high-strength low-alloy X70 steels under sour gas conditions

Quiñones,

Condori,

Apaza-Apaza

et al. 2024

Corrosion Engineering, Science and Technology: The Internationa

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“…Сегрегацію можна описати [3]. За допомогою ефективного коефіцієнта розподілу, який характеризує хімічну неоднорідність того чи іншого хімічного елемента, тобто співвідношення максимальної і мінімальної його концентрації.…”

Section: аналіз досліджень і публікаційunclassified

“…Майже всі присутні в сталі хімічні елементи позитивно сегрегують, тобто накопичуються в рідкому розплаві. Важливими винятками на думку авторів [3] є Si, Al (приблизно до 3 %), Cu, Ni та Co, які сегрегують негативно.…”

Section: аналіз досліджень і публікаційunclassified

STUDY OF THE INFLUENCE OF THE Si/Mn CONTENT RATIO ON THE DENDRITIC STRUCTURE OF STEELS FOR RAILWAY AXLES

Babachenko¹,

Balakhanova²,

Safronova³

et al. 2022

НМТ

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Purpose. Investigation of the effect of different total concentration and ratio of Si and Mn content on the dendritic structure and segregation inhomogeneity of cast carbon steel and its transformation after hot plastic deformation. Methods of research. To determine the effect of the content of Si and Mn, experimental ingots with a variable chemical composition within the grade were made for three steel grades used for the manufacture of railway axles – grade OS according to DSTU 31334, F according to AAR M 101 and EA1N according to EN 13261. To determine the dendritic structure microstructural analysis was used after etching in sodium picrate. Results. A comparative analysis of the microstructure of the experimental heats of steels with a variable chemical composition has been carried out. The ratio of content in steel Si and Mn in the cast state and after deformation is established. A significant effect of the total deoxidation in steel on the formation of microhardness inhomogeneity over the cross section of a carbon steel ingot and microinhomogeneity of the structure of individual sections is shown. It was found that after deformation, the central zones turned out to be the most worked out (especially for steel with a chemical composition within the EA1N grade, characterized by an increased content of Mn). Scientific novelty. The study of the influence of fluctuations in the content of the basic elements of carbon steel leads to the development of ideas about the formation of a dendritic structure and segregation heterogeneity in railway axle steels. Рractical value. Knowledge of the principles of segregation formation is necessary to determine further modes of deformation and heat treatment not only for continuously cast billets or ingots, but also for final products.

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“…In practice, segregations after heat treatment can often be noticeable by a banded microstructure, fibers or carbide bands that occur over the thickness of the sheet metal depending on the chemical composition of the alloy. 6 For example, Ramazani et al investigated the difference in the cold formability of dual-phase (DP) steels with and without a banded microstructure in tensile and bending tests. The results indicate that DP steel with banded microstructure shows worse failure behavior than DP steel with equiaxed microstructure due to localized martensite cracking.…”

Section: Introductionmentioning

confidence: 99%

Improvement of process control in sheet metal forming by considering the gradual properties of the initial sheet metal

Zettl

Schmid

Pulvermacher

et al. 2023

The Journal of Strain Analysis for Engineering Design

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In scientific studies, sheet metal is usually considered as a two-dimensional body. Thus, it is accepted that material properties are in most cases regarded homogeneous in thickness direction. However, a gradation of certain properties becomes apparent when going beyond the standard characterization methods for sheet metals, which can for example, influence the springback behavior and the thinning of the sheet after forming. Thus, the aim of this work is to further improve the prediction accuracy of springback after forming in simulations, by implementing several inhomogeneous properties over the sheet thickness in an existing material model. For this purpose, the entire procedure from the identification of the inhomogeneous properties for describing the gradation to the implementation in a numerical model and its validation by comparing experimental and simulated bending operations is carried out on a DC04 cold-forming steel in order to prove its influence on the springback behavior. It is shown that including graded material properties in simulations does indeed have an impact on the prediction quality of springback and that the information about inhomogeneous properties can be provided by existing characterization methods with a high local resolution like electron backscatter diffraction or X-ray stress analysis. In a further step, it was possible to validate the improvement in numerical accuracy by comparing the prediction of the springback angle from both the existing and the extended model with experimental bending results. Both the initial model as well as the model supplemented with the 3D properties provide a good prediction accuracy in the solution heat treated material state. For the predeformed material, however, the initial numerical model predicts a springback angle of about 13°, which deviates remarkably from the experimentally obtained mean value of about 17°. The extended model delivers a significantly improved accuracy in springback prediction in relation to the initial prediction (deviation of 4°) with a minor deviation of only about 0.8°, which proves the importance of considering the gradation of material properties in thickness direction for an overall higher dimensional accuracy of sheet metal products.

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Segregations in Steels during Heat Treatment – A Consideration along the Process Chain

Cited by 12 publications

References 65 publications

Evaluation of corrosion behaviour and susceptibility to hydrogen-induced cracking in high-strength low-alloy X70 steels under sour gas conditions

Evaluation of corrosion behaviour and susceptibility to hydrogen-induced cracking in high-strength low-alloy X70 steels under sour gas conditions

STUDY OF THE INFLUENCE OF THE Si/Mn CONTENT RATIO ON THE DENDRITIC STRUCTURE OF STEELS FOR RAILWAY AXLES

Improvement of process control in sheet metal forming by considering the gradual properties of the initial sheet metal

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