Article
Materials Science, Multidisciplinary
Alexandros Banis, Marianthi Bouzouni, Evangelos Gavalas, Spyros Papaefthymiou
Summary: This study focuses on the microstructure evolution of a medium-carbon steel during an ultra-fast heating cycle, revealing the presence of martensite, lower bainite, and retained austenite in the microstructure, attributed to the heterogeneity of the chemical composition.
MATERIALS TODAY COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Shuang Wen, Yi Liu, Zhen Chen, Manuel Lopez, Shaofei Qu, Xianhong Han
Summary: Resistance heating (RH) is a promising method for rapid and efficient heating in hot stamping. This study investigated the effects of heating temperature and current density on the mechanical properties and microstructure of ultra-high strength boron steel. The results showed that resistance heating significantly reduced heating time and improved surface quality. Moreover, the boron steel exhibited better mechanical properties after resistance heating compared to furnace heating, with a finer grain size and a certain amount of retained austenite.
JOURNAL OF MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Marc Ackermann, Deniz Iren, Sebastian Wesselmecking, Deekshith Shetty, Ulrich Krupp
Summary: This study utilized deep learning to quantify the martensite-austenite (M-A) islands in bainite. The research found that the ratio of constituent to image size during data pre-processing is a crucial parameter affecting the accuracy of subsequently trained models.
MATERIALS CHARACTERIZATION
(2022)
Article
Materials Science, Multidisciplinary
Marc Ackermann, Deniz Iren, Yao Yao
Summary: Microstructures in steel contain information on various length scales and can be extracted from electron microscopy images. However, current approaches for selecting important microstructural features are limited, resulting in hidden features. Machine learning is used in this study to correlate important morphological features with mechanical properties, and the learned correlation is tested on different bainitic steels.
MATERIALS & DESIGN
(2023)
Article
Metallurgy & Metallurgical Engineering
Junya Kobayashi, Ryo Sakata, Naoya Kakefuda, Goroh Itoh, Tomohiko Hojo
Summary: This study aims to investigate the role of retained austenite in hydrogen embrittlement of TRIP-aided bainitic ferrite steel (TBF steel), revealing that hydrogen embrittlement of TBF steel sheet is suppressed with increasing austempering time.
ISIJ INTERNATIONAL
(2021)
Article
Materials Science, Multidisciplinary
Ming-Feng Chiang, Ping-Hui Chien, Tzu-Yuan Lo, Ren-Kae Shiue
Summary: A nickel-based filler wire, Inconel 82, was used to weld a high-silicon steel plate with a deviation in chemical composition due to incomplete mixing/convection. The microstructure of the weld bead was primarily composed of austenite and martensite, mainly influenced by the Ni concentration. A Schaeffler diagram was utilized to predict the structure and phase(s) of the Fe-based weld bead. This study proposes a methodology for analyzing weld metal with unconventional alloy compositions.
Article
Nanoscience & Nanotechnology
Xiaowen Sun, Dongyun Sun, Yuefeng Wang, Yiting Feng, Long Jin, Xiaohong Hao, Tiansheng Wang, Fucheng Zhang
Summary: In this study, the influence of microstructural features on strain distribution and TRIP effect in multiphase steel was investigated. The results show that the strain partitioning in the multiphase microstructure is different depending on the presence of pre-formed martensite. The introduction of pre-formed martensite enhances the TRIP effect and promotes uniform strain partitioning, thereby improving the plasticity of the multiphase steel.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Rui Su, Jintao Chen, Hui Chen, Zhiyi Zhang, Xu Zhao, Zheng Lei, Dirui Wang, Yunfei Meng, Zhenlin Zhang
Summary: The low-temperature impact toughness of a low-carbon bainitic steel joint for high-speed trains was evaluated using laser-arc hybrid welding. The microstructure of each micro-zone in the welded joint was mainly bainite, but with different morphology and size. The impact toughness varied in each micro-zone due to the content of high-angle grain boundaries and the size of martensite-austenite (M-A) constituent.
JOURNAL OF MATERIALS SCIENCE
(2023)
Article
Chemistry, Physical
Guangjie Zhang, Qinggang Zhang, Junfeng Yang, Zhuoming Xie, Linchao Zhang, Rui Liu, Gang Li, Hui Wang, Qianfeng Fang, Xianping Wang
Summary: This study characterizes the tensile properties and microstructure changes of tempered 9Cr-F/M steel under different stress states using various microscopy techniques. It was found that the strength of the steel decreases at elevated temperatures, but the elongation at 400 degrees Celsius is lower than that at room temperature. Tensile deformation causes grain elongation in the direction of applied stress and reduces the grain's cross-section. The deformation in the transverse direction is more severe than that in the normal direction for samples with rectangular working area cross-section, resulting in grain elongation in the transverse direction.
Article
Materials Science, Multidisciplinary
Behzad Avishan, Sepideh Mohammadzadeh Khoshkebari, Sasan Yazdani
Summary: Partial quenching below the martensite start temperature accelerates bainite transformation in nanostructured bainitic steels, affecting the strength-ductility combinations. The study found that pre-existing martensite changed the amount of high carbon retained austenite, increasing carbon content in solid solution and dislocation density in austenite. Microstructural changes resulted in strength promotion, reduction of elongation and impact energy, while still maintaining an acceptable balance of strength-elongation-impact energy.
MATERIALS CHEMISTRY AND PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Kaifang Li, Lihe Qian, Chaozhang Wei, Wenlu Yu, Limei Ren, Zhaoxiang Chen, Fucheng Zhang, Jiangying Meng
Summary: In this study, the isothermal bainite transformation kinetics, microstructure, crystallography, and mechanical properties of a carbide-free bainitic steel subjected to pre-quenching treatment were investigated. It was found that the austenitization temperature plays a crucial role in the transformation rate and microstructure.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Jungang Han, Hao Yu, Kun Wang, Baichuan Hao, Shiyun Liu
Summary: This study adopts electromagnetic induction heat treatment technology to achieve ultra-fast heating and investigates its influence mechanism on the softening behavior of cold-rolled ribbed steel bars. The results show that induction heating promotes the movement of defects and dislocation annihilation, accelerating the softening process and controlling the size of recrystallized grains, ensuring high strength, high plasticity, and high ductility.
JOURNAL OF MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Adam Stahlkrantz, Peter Hedstrom, Niklas Sarius, Annika Borgenstam
Summary: The study investigates the variant pairing tendencies of a low alloy medium carbon bainitic steel during austempering at different temperatures. It finds distinct changes in variant pairing at various temperature ranges. The observations suggest similarities with variant pairing changes in martensite with varying carbon content.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2021)
Article
Nanoscience & Nanotechnology
L. S. Derevyagina, A. Gordienko, N. S. Surikova, M. N. Volochaev
Summary: The study showed that adjusting the helical rolling temperature can effectively improve the impact toughness of X65 low-carbon microalloyed steel. Lowering the rolling temperature helps reduce the area size of the microstructures and replace them with slender components, thereby enhancing fracture toughness at low temperatures. The highest impact energy level was achieved after helical rolling at 850 degrees Celsius.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Yanhui Wang, Qingsong He, Qian Yang, Dong Xu, Zhinan Yang, Fucheng Zhang
Summary: The research in this paper introduces a new low-carbon alloy gear steel designed with Si/Al alloying. Through carburizing and austempering processes at specific temperatures and times, different microstructures were achieved on the surface and core of the gear steel. The results show that the Si/Al-rich gear steel exhibits excellent mechanical properties and high wear resistance after specific heat treatment, meeting the technical requirements of heavy-duty gear steel applications. This research provides valuable data for the use of carburized steel with mixed bainitic ferrite and martensite microstructures in heavy-duty gear design.
Article
Materials Science, Multidisciplinary
Antonis Baganis, Marianthi Bouzouni, Spyros Papaefthymiou
Summary: The study investigated the effects of heat treatment on the microstructure and mechanical properties of Al-Mg-Si alloys using a Phase-Field modeling approach. It focused on recrystallization and grain growth mechanisms, as well as the calculation of yield strength and hardness after different ageing treatments. The results showed that the pinning force of secondary particles led to a slight decrease in final grain radius, and different ageing temperatures had an impact on ageing conditions for distinct ternary systems.
Article
Materials Science, Multidisciplinary
Eliseo Hernandez-Duran, Luca Corallo, Tanya Ros-Yanez, Felipe Castro-Cerda, Roumen H. Petrov
Summary: The study shows that multistep thermo-cycling and ultrafast heating strategies can produce similar levels of microstructural refinement, but do not improve mechanical properties significantly. On the other hand, ultrafast heating annealing combined with austempering can enhance ductility without sacrificing strength, achieving the best strength-ductility balance among the studied steels. The outstanding mechanical response exhibited by the ultrafast heating steel is attributed to a heterogeneous distribution of ferrite, bainite, and retained austenite.
Editorial Material
Materials Science, Multidisciplinary
Ilchat Sabirov, Maria J. Santofimia, Roumen H. Petrov
Editorial Material
Materials Science, Multidisciplinary
Spyros Papaefthymiou
Editorial Material
Materials Science, Multidisciplinary
Marianthi Bouzouni, Evangelos Gavalas, Spyros Papaefthymiou
Summary: This study presents a simulation approach to investigate the phase transformation and microstructure evolution of a low-Si CrMo steel processed with a typical Q & P cycle. The simulation accurately predicted the austenite grain size, the fraction and size of microstructural constituents at different stages of the Q & P process. The results showed that the solute drag effect of Cr restricts the growth of austenite grain size, and the heating stage is crucial for estimating the grain size. The phase field method successfully predicted the fraction of initial martensite, and the carbon content in the microstructural constituents determined the fraction of bainitic ferrite and retained austenite at the end of partitioning. It was found that accurate prediction of carbon diffusion is important for accurately predicting the carbon content in the microstructure. The simulation results were in good agreement with experimental data, demonstrating the effectiveness of the simulation approach in predicting phase transformations during the Q & P process.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Chemistry, Physical
Spyridon Chaskis, Eva Stachouli, Evangelos Gavalas, Marianthi Bouzouni, Spyros Papaefthymiou
Summary: In this study, a novel complex concentrated aluminum alloy was designed and studied using the CALPHAD method. The alloy exhibited a multiphase microstructure with an alpha-Al matrix and various secondary phases. The mechanical properties of the alloy were also investigated, showing high hardness and compressive strength.
Article
Materials Science, Multidisciplinary
Leo A. Kestens, Tuan Nguyen-Minh, Roumen H. Petrov
Summary: This paper investigates the influence of parent phase topology on the variant selection rule in crystalline materials. It is found that certain grain boundaries in the parent structure exhibit a specific crystallographic orientation relationship with the product phase, known as the Young-Kurdjumow-Sachs (YKS) orientation relationship. The study shows that around 20% of grain boundaries in different parent phase textures comply with the double YKS condition, regardless of the parent phase microstructure topology. The findings of this research provide insight into the formation of specific transformation textures in various practical cases.
Article
Materials Science, Multidisciplinary
Adam Skowronek, Adam Grajcar, Aleksandra Kozlowska, Aleksandra Janik, Mateusz Morawiec, Roumen H. Petrov
Summary: This study investigates the impact of heat-treatment processes on automotive medium-Mn sheet steels. A new method for calculating high-temperature phase equilibrium is developed and validated through experiments. The results show that the intercritical annealing temperature has a significant influence on the microstructure, chemical stability, and mechanical properties of the medium-Mn Al-alloyed steel.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2022)
Article
Nanoscience & Nanotechnology
Adam Skowronek, Erick Cordova-Tapia, Pilar Tobajas-Balsera, Carlos Garcia-Mateo, Jose A. Jimenez, Roumen Petrov, Adam Grajcar
Summary: The novel use of double austempering treatments in a multiphase steel has been studied to refine and homogenize the microstructure and improve material strength. The two-step heat treatments effectively reduced blocky-type austenite and fresh martensite while retaining a high volume fraction of retained austenite. The microstructural characteristics, including reduced bainitic plate thickness and film-like retained austenite, led to a significant increase in hardness (50 HV) and yield strength (180 MPa).
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Amke Lescur, Erich Stergar, Jun Lim, Stijn Hertele, Roumen H. Petrov
Summary: Austenitic stainless steels, such as AISI 316L, are widely used in nuclear reactors and their development and characterization is crucial for ensuring structural integrity. The 3D-DIC technique was successfully used to characterize the behavior of multi-pass welds and base materials, providing accurate local strain calculations. The difference in dynamic strain aging effect between the base and weld materials was identified, with the weld materials showing discontinuous type A PLC bands. This technique allows for a better understanding of the local and global behavior of materials.
Article
Nanoscience & Nanotechnology
Alexandros Banis, Andrea Gomez, Vitaliy Bliznuk, Aniruddha Dutta, Ilchat Sabirov, Roumen H. Petrov
Summary: This study investigates the microstructure evolution of a high-strength low-density steel under different aging conditions. The formation and growth of an ordered face-centered cubic L12 phase called x-carbide are characterized qualitatively and quantitatively. The optimal aging condition is determined to achieve a good combination of strength and ductility. Increasing the aging temperature and time leads to the formation of intergranular x-carbides that compromise the hardness and strength of the steel.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Adam Skowronek, Adam Grajcar, Carlos Garcia-Mateo, Jose A. Jimenez, Roumen H. Petrov
Summary: The present study explores the possibility of using continuous annealing approach in Al-alloyed 5Mn steel to optimize the superior mechanical properties in medium-Mn. The microstructural changes as a function of time were followed by dilatometric studies at 680 oC with different soaking times, and thoroughly characterized using various techniques. It was observed that with increasing soaking times, the volume fraction of retained austenite gradually increases, but at the cost of its stability. Mechanical tests results showed a decrease in yield stress, tensile strength and hardness with increasing intercritical annealing soaking time.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Ksenija Nikolic, Jelle De Wispelaere, Gopalakrishnan Ravi, Stijn Hertele, Tom Depover, Kim Verbeken, Roumen H. Petrov
Summary: Damage in bearings is closely related to microstructural alterations, known as white etching areas (WEAs) and white etching cracks (WECs). Non-metallic inclusions, such as manganese sulfides and aluminum oxides, are common in bearing steels. This study classifies 280 non-metallic inclusions according to various criteria and finds that the chemical composition is of secondary importance in damage initiation. The observations suggest that the state of non-metallic inclusion plays a crucial role in initiating rolling contact fatigue damage.
Article
Materials Science, Multidisciplinary
O. Kachko, A. Puype, D. Terentyev, M. Duerrschnabel, M. Klimenkov, R. H. Petrov
Summary: Two RAFM alloys with improved microstructures and mechanical properties were designed and tested, showing higher yield and tensile strength without sacrificing impact toughness. This improvement was achieved through dedicated chemical and thermal treatments, resulting in refined grain and subgrain size and a high density of dislocations. TEM investigation was conducted to quantitatively describe the microstructural parameters and calculate the strengthening contribution of each microstructural feature.
JOURNAL OF NUCLEAR MATERIALS
(2023)
