Key Takeaways & Executive Findings
- •• Lamellarization (QLT) significantly improves cryogenic toughness of marine 10Ni5CrMoV steel, lowering ductile–brittle transition temperature from −116°C to −130°C. • Film-like reversed austenite formed at martensite boundaries refines the microstructure and reduces equivalent grain size, enhancing toughness. • Kinetic analysis using JMAK model reveals that isothermal transformation is growth-controlled, with maximum reversed austenite at 750°C. • Reversed austenite reduces martensite proportion and hinders crack propagation via transformation-induced plasticity, improving machinability.
Abstract
Multistage heat treatment involving quenching (Q), lamellarizing (L), and tempering (T) is applied to marine 10Ni5CrMoV steel. The microstructure and mechanical properties were studied by multiscale characterizations, and the kinetics of reverse austenite transformation, strain hardening behavior, and toughening mechanism were further investigated. The lamellarized specimens possess low yield strength but high toughness, especially cryogenic toughness. Lamellarization leads to the development of film-like reversed austenite at the martensite block and lath boundaries, refining the martensite structure and lowering the equivalent grain size. Kinetic analysis of austenite reversion based on the JMAK model shows that the isothermal transformation is dominated by the growth of reversed austenite, and the maximum transformation of reversed austenite is reached at the peak temperature (750°C). The strain hardening behavior based on the modified Crussard–Jaoul analysis indicates that the reversed austenite obtained from lamellarization reduces the proportion of martensite, significantly hindering crack propagation via martensitic transformation during the deformation. As a consequence, the QLT specimens exhibit high machinability and low yield strength. Compared with the QT specimen, the ductile–brittle transition temperature of the QLT specimens decreases from −116 to −130°C due to the low equivalent grain size and reversed austenite, which increases the cleavage force required for crack propagation and absorbs the energy of external load, respectively. This work provides an idea to improve the cryogenic toughness of marine 10Ni5CrMoV steel and lays a theoretical foundation for its industrial application and comprehensive performance improvement.
1. Introduction
High-strength low-alloy steel (HSLA) has an excellent combination of strength and toughness and is widely used in the automotive industry, marine structural materials, and infrastructure construction [1–3]. The structural materials used for marine applications require great safety for deep ocean exploration, and HSLA steels for marine applications must exhibit excellent cryogenic toughness [4–6]. In general, marine HSLA steel obtained by traditional heat treatment (quenching and tempering) possesses high strength but poor cryogenic toughness. Scholars at home and abroad have recently focused on improving the cryogenic toughness of marine HSLA steel [7–9].
Quenching–lamellarizing–tempering (QLT) is a multistage heat treatment in which lamellarization (L) is introduced after quenching. Compared with QT, QLT can significantly improve the cryogenic toughness of materials [9–11]. The reversed austenite (RA) obtained during lamellarization usually develops along the martensite (M) laths and prior austenite grain boundaries [12], “cleaning” the grain boundaries and hindering the propagation of cracks due to the enrichment of austenite-stabilizing elements such as C, Mn, and Ni, especially in Ni-containing cryogenic steels where the RA plays a role in improving their cryogenic toughness [13–15]. At present, research on the QLT of Ni-containing martensitic cryogenic steels focuses on the influence of lamellarization on cryogenic toughness. The RA obtained by lamellarization is unstable, resulting in hardening during the strain process due to the martensite transformation. Therefore, the influence of lamellarization on strain hardening behavior warrants further study.
In this work, marine Ti microalloyed 10Ni5CrMoV steel was subjected to QT and QLT. The kinetics of reverse austenite transformation, strain hardening behavior, and toughening mechanism were systematically investigated. Multiscale characterizations involving scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were conducted to describe the microstructural features. This research provides a theoretical basis and experimental reference for exploring the comprehensive performance of marine 10Ni5CrMoV steel.
Loading authentic research manuscript (Pages 1–5)...
Tao Zou, Yanwu Dong, Zhouhua Jiang, Shuyang Du, Yushuo Li (2025). Effect of lamellarization on the microstructure and mechanical properties of marine 10Ni5CrMoV steel. Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报). https://doi.org/10.1007/s12613-024-2897-5
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the effect of lamellarization on the cryogenic toughness of 10Ni5CrMoV steel?
Lamellarization significantly improves cryogenic toughness, lowering the ductile–brittle transition temperature from −116°C to −130°C, due to refined microstructure and formation of reversed austenite.
How does reversed austenite improve the mechanical properties of the steel?
Reversed austenite forms at martensite boundaries, refining the structure and reducing equivalent grain size. It also hinders crack propagation through transformation-induced plasticity, enhancing toughness while slightly reducing yield strength.
What is the optimal lamellarizing temperature for maximum reversed austenite?
According to JMAK kinetic analysis, the maximum transformation of reversed austenite occurs at the peak temperature of 750°C.
What are the advantages of QLT over QT heat treatment for marine steels?
QLT provides better cryogenic toughness and machinability, with a lower ductile–brittle transition temperature, making it more suitable for marine applications requiring high safety at low temperatures.
What characterization techniques were used in this study?
The study employed multiscale characterizations including scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) to analyze microstructural features.
Related Technical Papers & Translations
Direct Repair of the Crystal Structure and Coating Surface of Spent LiFePO4 Materials Enables Superfast Li-Ion Migration
The rapid accumulation of spent LiFePO4 (LFP) cathodes from retired lithium-ion batteries necessitates the development of effective and environmental-friendly recycling strategies. In this context, direct regeneration has emerged as a promising approach for reclaiming LFP cathode materials, offering a streamlined pathway to restore their electrochemical functionality. We report an integrated regeneration protocol that simultaneously repairs the degraded crystal structure and reconstructs the damaged carbon coating in spent LFP. The regenerated cathode material had superfast lithium-ion diffusion kinetics and a stable cathode–electrolyte interface, giving a remarkable rate capability with specific capacities of 122 mAh g−1 at 5C and 106 mAh g−1 at 10C (1C = 170 mA g−1). It also maintained capacities of 110.7 mAh g−1 (5C) and 84.1 mAh g−1 (10C) after 400 cycles. It could be used in harsh environments and could be stably cycled at subzero temperatures (−10 and −20 °C) and in solid-state electrolyte batteries. Life cycle assessment combined with economic evaluation using the EverBatt model reveals that this direct regeneration approach has high economic and environmental benefits.
Oxide Semiconductor for Advanced Memory Architectures: Atomic Layer Deposition, Key Requirement and Challenges
Oxide semiconductors (OSs), introduced by the Hosono group in the early 2000s, have evolved from display backplane materials to promising candidates for advanced memory and logic devices. The exceptionally low leakage current of OSs and compatibility with three-dimensional (3D) architectures have recently sparked renewed interest in their use in semiconductor applications. This review begins by exploring the unique material properties of OSs, which fundamentally originate from their distinct electronic band structure. Subsequently, we focus on atomic layer deposition (ALD), a core technique for growing excellent OS films, covering both basic and advanced processes compatible with 3D scaling. The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced. Furthermore, material design strategies, such as cation selection, crystallinity control, anion doping, and heterostructure engineering, are discussed. We also highlight challenges in memory applications, including contact resistance, hydrogen instability, and lack of p-type materials, and discuss the feasibility of ALD-grown OSs as potential solutions. Lastly, we provide an outlook on the role of ALD-grown OSs in memory technologies. This review bridges material fundamentals and device-level requirements, offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.
Laser powder bed fusion of biodegradable Zn-4Cu alloy: Processing, microstructure and properties
Zn's natural degradability and biocompatibility make it a promising candidate for implants, however, its mechanical properties remain insufficient for bone applications. In this study, the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion (LPBF). Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed. Under optimized conditions of 100 W and 100 mm/s, high-density (99.58%) Zn-Cu alloys with improved hardness (68.2HV) and yield strength (160 MPa) were achieved. These improvements are attributed to solid solution strengthening, segregation strengthening, and grain refinement. The Zn-Cu alloys also demonstrated favorable degradation behavior, with a rate of 0.16 mm/year. This degradation is primarily driven by micro-galvanic corrosion between the CuZn5 phase and Zn matrix, along with refined grains and increased grain boundary density. This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.