Characterization of the Microstructure and Precipitates Formed During the Thermomechanical Processing of a CrNiMoWMnV Ultrahigh‐Strength Steel

Ali, Mohammed; Porter, David; Kömi, Jukka; Eissa, Mamdouh; Faramawy, Hoda El; Mattar, Taha

doi:10.1002/srin.201900580

Cited by 10 publications

(4 citation statements)

References 19 publications

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“…Other elements such as Fe, Cr, O, and Si in Figure 4c may result from the preparation process. [ 38 ] N element is not detected since it is a light element. These small‐sized precipitates were identified as Nb(C,N), which may be the strain‐induced precipitates on the dislocations.…”

Section: Resultsmentioning

confidence: 99%

AlN and Nb(C,N) Composite Precipitation Behaviors and Their Effects on Austenite Grain Growth in SCr420H High‐Temperature Carburized Gear Steel

Gong,

Wang,

Chen

2024

steel research int.

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The effects of nitrogen (N) and niobium (Nb) contents on the precipitation behaviors of AlN, Nb(C,N), and AlN‐Nb(C,N) precipitates and austenite grain growth during the pseudo‐carburizing process are investigated for the carburized steel SCr420H. The results indicate that an increase of N content from 0.011% to 0.019% leads to the emergence of fine and uniform austenite grain structure in the sample while being held at 930 °C for 6 h, which is attributed to a notable rise in the number density of AlN and a decrease in the coarsening rate of AlN. In the steel containing 0.023% Nb, the composite precipitates AlN‐Nb(C,N) play a primary role in the pinning effect on austenite grains growth. The isolated Nb(C,N) and AlN precipitates have minor pinning effects due to their very low volume fractions. Nb(C,N) cap forming on AlN substrate obeys the Shoji–Nishiyama orientation relationship. The favorable lattice matching between AlN and Nb(C,N) and accelerated coarsening rate of Nb(C,N) cap decrease hindrances to the nucleation, growth, and coarsening of Nb(C,N) on AlN substrate. Meanwhile, these simultaneous effects also suppress the same processes for the isolated Nb(C,N) in the matrix.

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Section: Resultsmentioning

confidence: 99%

AlN and Nb(C,N) Composite Precipitation Behaviors and Their Effects on Austenite Grain Growth in SCr420H High‐Temperature Carburized Gear Steel

Gong,

Wang,

Chen

2024

steel research int.

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“…After carbon coating to ensure conductivity, imaging and EDS analysis of the extracted precipitates were carried out with a JEOL JSM-7900F FESEM. Moreover, the small precipitates were investigated using EDS analysis and STEM imaging of carbon extraction replicas prepared using the method described by Ali et al [12]. The distribution of Mo and Nb as soluble (steel matrix) and insoluble (precipitates) was also studied with the electrolytic extraction method in a similar manner.…”

Section: Methodsmentioning

confidence: 99%

Effect of Mo and Mo+Nb Additions on the Phase Transformation and Microstructure of a Developed Low-Carbon CrNiMnB Ultrahigh-Strength Steels with a Preceding Hot Deformation

Ali,

Alatarvas,

Nyo

et al. 2023

MSF

Self Cite

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The influence of molybdenum, and molybdenum with niobium addition on the phase transformation behaviour of a developed low-carbon CrNiMnB ultrahigh-strength steels, was investigated. Gleeble 3800 thermomechanical simulator was employed to simulate the hot-rolling process and to get the dilatation curves. After austenitization at 1250 °C for the complete dissolution of carbides, specimens received 0.6 total strain (i.e., 0.2 at 1100 °C and 2 x 0.2 at 900 °C) followed by cooling at various cooling rates (CRs) in the range of 2-60 °C/s. The final microstructures were investigated using laser scanning confocal microscopy, field emission scanning electron microscopy, and hardness measurements. Then the continuous cooling transformation diagrams were constructed based on the dilatation curves, microstructure, and hardness values. The electrolytic extraction method was used to assess the elements' distribution and the composition of the forming precipitates. The addition of Mo increased the hardenability, decreased the transformation temperatures, and promoted the formation of low-temperature transformation products i.e., martensite and bainite ferrite, at different CRs and inhibit the formation of polygonal ferrite. The formation of coarse precipitates neglected the effect of Mo+Nb addition, decreased the hardenability and expanded the region of BF formation to high CRs. The variation in the hardness with microstructural changes was discussed.

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“…For the grain boundaries with an irregular shape, the diameter of an equivalent circle whose domain was enclosed by HAGB was considered as the EGS. [ 12,13 ] The diameter of all the effective grains and the corresponding area was the output. Next, the curves of accumulated area fraction as a function of EGS were drawn by Origin software to reflect the size distribution and uniformity of effective grains in the scanning areas.…”

Section: Methodsmentioning

confidence: 99%

Mechanism for Refining Grains and Effect of Microstructural Characteristics on Low‐Temperature Toughness for Industrial EH460 Heavy‐Gauge Steel

Wang

Tian

Kan

et al. 2021

steel research int.

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The mechanism for refining grains in industrial EH460 heavy‐gauge steel with a thickness of 80 mm and above is investigated using electron backscattered diffraction. Charpy impact and drop‐weight tests are conducted to quantify the effect of microstructures and texture on low‐temperature toughness. Abundant ferrite grains that form and impinge from different prior‐austenite grains increase the high‐angle grain boundary (HAGB) fraction. The result is a refined effective grain size of 3.7 ± 4.2 μm, a high HAGB fraction of 62.1%, and an average Charpy impact absorbed energy of ≈209 J at −80 °C. The excellent impact toughness is due to the high intensity of texture with types of {113}−{112}<110> and {332}<113>, as well as the uniformly distributed {110} slip planes and {001} cleavage planes. The high intensities of {110}<111> and {110}<112> also improve the drop‐weight toughness. However, due to plastic constraint in the larger drop‐weight specimens, increased plane strain in the inner regions is the root cause of the brittle fracture of these specimens at −70 °C. Nevertheless, the improved drop‐weight performance is attributed to the plane stress deformation at the specimen edges and also the occurrence of delamination in the central section.

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Characterization of the Microstructure and Precipitates Formed During the Thermomechanical Processing of a CrNiMoWMnV Ultrahigh‐Strength Steel

Cited by 10 publications

References 19 publications

AlN and Nb(C,N) Composite Precipitation Behaviors and Their Effects on Austenite Grain Growth in SCr420H High‐Temperature Carburized Gear Steel

AlN and Nb(C,N) Composite Precipitation Behaviors and Their Effects on Austenite Grain Growth in SCr420H High‐Temperature Carburized Gear Steel

Effect of Mo and Mo+Nb Additions on the Phase Transformation and Microstructure of a Developed Low-Carbon CrNiMnB Ultrahigh-Strength Steels with a Preceding Hot Deformation

Mechanism for Refining Grains and Effect of Microstructural Characteristics on Low‐Temperature Toughness for Industrial EH460 Heavy‐Gauge Steel

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