PL
 |
EN
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 6

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
1
Content available In-Situ Observation of Acicular Ferrite Transformation in High-Strength Low-Alloy Steel Using Confocal Laser Scanning Microscopy
Lee Sang-In, Shin Seung-Hyeok, Park Hyeonwoo, Kim Hansoo, Lee Joonho, Hwang Byoungchul
Archives of Metallurgy and Materials
|
2022
|
Vol. 67, iss. 4
1497--1501
EN
In-situ observation of the transformation behavior of acicular ferrite in high-strength low-alloy steel using confocal laser scanning microscopy was discussed in terms of nucleation and growth. It is found that acicular ferrite nucleated at dislocations and slip bands in deformed austenite grains introduced by hot deformation in the non-recrystallization austenite region, and then proceeded to grow into an austenite grain boundary. According to an ex-situ EBSD analysis, acicular ferrite had an irregular shape morphology, finer grains with sub-grain boundaries, and higher strain values than those of polygonal ferrite. The fraction of acicular ferrite was affected by the deformation condition and increased with increasing the amount of hot deformation in the non-recrystallization austenite region.
2
Content available Effects of the Coiling Temperature and Anisotropy on the Tensile Properties of High-Strength API X70 Linepipe Steel
Oh Dong-Kyu, Shin Seung-Hyeok, Lee Sang-Min, Hwang Byoungchul
Archives of Metallurgy and Materials
|
2022
|
Vol. 67, iss. 4
1487--1490
EN
In this study, the effect of the coiling temperature on the tensile properties of API X70 linepipe steel plates is investigated in terms of the microstructure and related anisotropy. Two coiling temperatures are selected to control the microstructure and tensile properties. The API X70 linepipe steels consist mostly of ferritic microstructures such as polygonal ferrite, acicular ferrite, granular bainite, and pearlite irrespective of the coiling temperature. In order to evaluate the anisotropy in the tensile properties, tensile tests in various directions, in this case 0° (rolling direction), 30°, 45° (diagonal direction), 60°, and 90° (transverse direction) are conducted. As the higher coiling temperature, the larger amount of pearlite is formed, resulting in higher strength and better deformability. The steel has higher ductility and lower strength in the rolling direction than in the transverse direction due to the development of γ-fiber, particularly the {111}<112> texture.
3
Content available Effect of Pre-strain on Hydrogen Embrittlement in Intercritically Annealed Fe-6.5Mn-0.08C Medium-Mn steels
Kim Sang-Gyu, Yoon Young-Chul, Ko Seok-Woo, Hwang Byoungchul
Archives of Metallurgy and Materials
|
2022
|
Vol. 67, iss. 4
1491--1495
EN
The present research deals with the effect of pre-strain on the hydrogen embrittlement behavior of intercritically annealed medium-Mn steels. A slow strain-rate tensile test was conducted after hydrogen charging by an electrochemical permeation method. Based on EBSD and XRD analysis results, the microstructure was composed of martensite and retained austenite of which fraction increased with an increase in the intercritical annealing temperature. The tensile test results showed that the steel with a higher fraction of retained austenite had relatively high hydrogen embrittlement resistance because the retained austenite acts as an irreversible hydrogen trap site. As the amount of pre-strain was increased, the hydrogen embrittlement resistance decreased notably due to an increase in the dislocation density and strain-induced martensite transformation.
4
Content available In-situ Observation of High-Temperature Fracture Behaviour of 347 Stainless Steel Subjected to Simulated Welding Process
Ko Seok-Woo, Park Hyeonwoo, Yoo Il, Kim Hansoo, Lee Joonho, Hwang Byoungchul
Archives of Metallurgy and Materials
|
2021
|
Vol. 66, iss. 4
1019--1022
EN
In-situ study on the high-temperature fracture behaviour of 347 stainless steel was carried out by using a confocal laser scanning microscope (CLSM). The welding microstructures of the 347 stainless steel were simulated by subjecting the steel specimen to solution and aging treatments. Undissolved NbC carbides were present within grains after solution treatment, and M23C6 carbides were preferentially formed at grain boundaries after subsequent aging treatment. The M23C6 carbides formed at grain boundaries worked as stress concentration sites and thus generated larger cracks during high-temperature tensile testing. In addition, grain boundary embrittlement was found to be a dominant mechanism for the high-temperature fracture of the 347 stainless steel because vacancy diffusion in the Cr-depleted zones enhances intergranular fracture due to the precipitation of M23C6 carbides at grain boundaries.
5
Content available Influence of Al, Cu and Ni Additions on Mechanical Properties of Hot-Rolled Fe-9Mn-0.2C Medium-Manganese Steels
Yoon Young-Chul, Kim Sang-Gyu, Lee Sang-Hyeok, Hwang Byoungchul
Archives of Metallurgy and Materials
|
2021
|
Vol. 66, iss. 4
1007--1011
EN
The microstructure and mechanical properties of hot-rolled Fe-9Mn-0.2C medium-manganese steels with different Al, Cu, and Ni contents were investigated in this study. Based on the SEM, XRD, and EBSD analysis results, the microstructure was composed of martensite, band-type delta ferrite, and retained austenite phases depending on the Al, Cu, and Ni additions. The tensile and Charpy impact test results showed that the sole addition of Al reduced significantly impact toughness by the presence of delta-ferrite and the decrease of austenite stability although it increased yield strength. However, the combined addition of Al and Cu or Ni provided the best combination of high yield strength and good impact toughness because of solid solution strengthening and increased austenite stability.
6
Content available Application of Artificial Neural Network to Predict the Tensile Properties of Dual-Phase Steels
Shin Seung-Hyeok, Kim Sang-Gyu, Hwang Byoungchul
Archives of Metallurgy and Materials
|
2021
|
Vol. 66, iss. 3
719--723
EN
An artificial neural network (ANN) model was developed to predict the tensile properties of dual-phase steels in terms of alloying elements and microstructural factors. The developed ANN model was confirmed to be more reasonable than the multiple linear regression model to predict the tensile properties. In addition, the 3D contour maps and an average index of the relative importance calculated by the developed ANN model, demonstrated the importance of controlling microstructural factors to achieve the required tensile properties of the dual-phase steels. The ANN model is expected to be useful in understanding the complex relationship between alloying elements, microstructural factors, and tensile properties in dual-phase steels.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.