Hydrogen embrittlement (HE) critically limits the application of ultra-high-strength press-hardened steels (PHS) in hydrogen-containing environments. This study investigated the effect of Nb microalloying on HE resistance of 1500 MPa-grade PHS. Even with higher hydrogen contents, steel 1500Nb exhibits better HE resistance than steel 1500. The results show that Nb addition plays effective role in grain refinement, mitigating stress concentration, and effectively postponing the initiation of intergranular cracks under hydrogen-charged conditions. Additional, hydrogen diffusivity in 1500Nb steel is lower than 1500 steel, attributed to both grain refinement effect and solute drag effect of Nb.

The hot deformation behavior and carbide evolution of 60Cr16MoMA high-carbon martensitic stainless steel (HCMSS) were studied by hot compression tests at 850 degrees C-1150 degrees C and strain rates of 0.001-1 s-1. An Arrhenius-type constitutive model with an activation energy of 423.32 kJ/mol was established. Furthermore, quantitative analysis of carbide morphology within the stable deformation regime demonstrates that carbide evolution is strongly governed by the lnZ parameter. An intermediate lnZ range promotes effective mechanical fragmentation of primary carbides, resulting in reduced carbide area, increased circularity, decreased fractal dimension, and modified nearest neighbor interparticle spacing. In contrast, excessively high or low lnZ values lead to limited carbide fragmentation due to excessive deformation resistance or high-temperature dissolution effects. Based on the processing maps and microstructural analysis, the optimal hot deformation window for the steel is identified as 950 degrees C with strain rates of 0.001-0.01 s-1 and 1000 degrees C-1150 degrees C with strain rates of 0.001-0.1 s-1.

The sliding contact between aluminum alloy sheet and H13 steel in hot stamping often leads to severe wear and adhesive transfer, significantly degrading forming quality and tooling life. This study simulates the actual solution-forming-quenching process of hot stamping on a self-developed sheet-and-strip high-temperature friction tester. This study reveals the influence of different normal pressures on the thermal tribological behavior between three types of surface-modified H13 steel, quenched and tempered (Q T) H13 steel:Q T H13 steel combined with ion plasma nitriding (PN), and Q T H13 steel combined with PVD-TiN coating (PVD-TiN) and high-temperature aluminum alloy. The experimental results show that with the increase of normal pressure, the coefficient of friction increases and adhesive wear is aggravated. The average coefficient of friction is 1.18 at 3.6 MPa and 1.34 at 5.4 MPa. Both PVD-TiN coating and nitriding coating exhibit excellent friction-reducing performance under different pressure conditions. Under the medium pressure condition of 4.5 MPa, the average coefficient of friction is 1.09 for PVD-TiN and 1.23 for PN, although the friction coefficient of the PVD-TiN surface-modified tool is lower than that of the surface nitrided tool, the adhesive wear is more severe than that of the surface nitrided tool because the thinner coating is prone to local spalling, exposing the fresh metal surface. However, the compounds such as Fe3N and Fe4N formed by nitriding treatment can effectively inhibit adhesion. Under the high-pressure condition of 5.4 MPa, the PVD-TiN surface-modified tool not only maintains a lower friction coefficient, the friction coefficient decreased from 1.34 in the untreated state to 1.14, but also the TiN particles formed on its surface can significantly reduce adhesive wear, showing better performance than the surface nitrided tool. The latter, however, deteriorates the contact condition of the friction pair due to the formation of Fe-Cr alloy aggregate particles caused by plastic deformation.

Addition of rare earth Ce to high-speed steel is a common approach to refining carbide size and optimizing carbide morphology, thereby enhancing the hot workability and mechanical properties. The effect of Ce on carbide refinement in steel typically varies with the oxygen content of the steel. In the present work, two M2 high-speed steel samples with identical Ce content but varying oxygen contents were prepared to clarify the differences in carbide morphology. The as-cast microstructure, hot workability, and carbide decomposition behavior of both steels were characterized using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), aberration-corrected transmission electron microscopy (AC-TEM), electron energy loss spectroscopy (EELS), and high-temperature tensile testing. The results demonstrate that the morphology of both primary and secondary carbides in Ce-added high-speed steel strongly depends on the oxygen content. At a low oxygen content of similar to 4 ppm, the primary M2C carbides exhibit an average length of similar to 3.2 mu m, approximately four times finer than that at the high oxygen content of similar to 12 ppm. Upon decomposition, the low-oxygen condition leads to fast growth and coalescence of MC carbides, which interrupts the subsequent coarsening of M6C carbides. Controlling the oxygen content to the lowest possible level enhances the efficiency of Ce-induced carbide refinement in high-speed steels, thereby improving hot workability.

Rare earth element cerium (Ce) has been widely used as a modifier in high-speed steel to refine its microstructure, thereby enhancing mechanical properties. The beneficial effect of Ce addition is closely correlated with the oxygen content. In this study, using a combination of experimental and computational methods, an attempt to improve the understanding of the role of Ce in carbide refining under very low oxygen conditions is made. Trace amounts of Ce were added to M2 high-speed steel, in which the oxygen content was controlled to be 3 ppm through deep deoxidation. The morphological and compositional evolution of primary and secondary carbides resulting from Ce addition was investigated using electron microscopy, micro-computed tomography, 3D atom probe tomography, and electron energy-loss spectroscopy. The results demonstrate that the addition of Ce to steel can prevent the continuous development of carbides and significantly refine carbide size, which is primarily ascribed to the compositional change induced by Ce addition. The added Ce mainly segregates to the steel matrix, providing additional solute trapping sites for carbide-forming elements such as W and Mo. This leads to the development of small-sized M2 C carbides, which readily decompose into finer M6 C and MC carbides upon subsequent hot processing. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Bone defects caused by various factors have become a persistent challenge in orthopedic clinics, and traditional treatment methods mainly comprise artificial bone or autologous bone transplantation. However, these methods have considerable limitations, such as bone depletion, immune rejection, and the risk of secondary infection at the donor site. Therefore, considering these limitations and the rapid development of the field of bone tissue engineering, this study adopted light-curing stereolithography three-dimensional (3D)-printing technology to design bone scaffold materials. The technology was used to prepare hydroxyapatite (HA)/zirconium dioxide (ZrO2) porous composites with satisfactory mechanical properties as tissue engineering bone scaffold materials. A BMP-2 loaded gelatin/chitosan hydrogel sustained-release system was prepared via an emulsification and cross-linking process. Subsequently, rhesus macaque bone marrow mesenchymal stem cells (BMSCs) were seeded into the system acting as osteogenic progenitors. Novel HA/ZrO2 scaffolds were fabricated using stereolithography (SLA) 3D printing technology to serve as bone graft substitutes. The resulting scaffold exhibited a 3D interconnected porous structure and showed good biocompatibility and osteoinductive ability in a rhesus macaque lumbar vertebral bone defect model. The results confirmed that the scaffold achieved osteogenic efficiency comparable to that of autologous bone grafting in rhesus macaques. Therefore, the developed scaffold material has promising potential in bone defect repair.

During hot stamping,the sliding contact between an aluminum alloy sheet and H13 tool steel often results in severe wear and adhesive material transfer.These tribological phenomena can significantly degrade forming quality and reduce die service life.In this study,the high-temperature tribological behavior of a heated 7075 aluminum alloy sheet sliding against H13 steel was investigated under conditions designed to simulate the aluminum hot-stamping practice.Experiments were conducted using a self-developed strip-type high-temperature friction tester.Based on the actual process sequence for aluminum hot stamping,the tester was used to reproduce a combined"solution treatment-forming-quenching"cycle such that the friction pair experienced thermal and mechanical histories similar to those encountered in industrial production.The main purpose was to elucidate how normal pressure and die surface condition i nfluenced friction evolution,adhesive transfer,and the dominant wear mechanisms at elevated temperature.Three representative surface conditions of H13 steel were examined:(I)quenched and tempered(Q&T);(II)plasma nitrided after Q&T(PN);and(III)physical vapor deposition TiN coating applied after Q&T(PVD-TiN).Under different normal loads,the coefficient of friction and extent of adhesive wear/transfer were quantified and the friction and wear mechanisms were analyzed for each surface condition.The results show that as the normal pressure increases,the friction coefficient generally rises and adhesive wear becomes more severe.Higher contact pressure increases the real area of contact and promotes stronger interfacial bonding between the softened,high-temperature 7075 aluminum and steel surface,thereby accelerating sticking,tearing,and the formation of transfer layers.In contrast,both the PVD-TiN coating and plasma-nitrided layer exhibit excellent friction-reducing performance compared with the baseline Q&T surface,indicating that surface engineering is an effective approach for mitigating galling during aluminum hot stamping.At a moderate pressure of 4.5 MPa,the PVD-TiN surface produces a lower coefficient of friction than the nitrided surface.However,because the TiN coating is relatively thin,it can undergo local spallation under combined thermal effects and tangential shear.Once delamination occurs,the fresh metallic substrate is exposed,providing highly reactive sites that facilitate strong adhesion to the aluminum sheet.As a result,despite the lower measured friction coefficient,adhesive wear on the PVD-TiN die surface is more pronounced than on the nitrided die under this intermediate-pressure condition.By comparison,the plasma-nitrided layer contains nitride compound phases,such as Fe3N and Fe4N,which create a harder and more chemically stable near-surface region and can effectively suppress adhesion,thereby reducing material pickup and transfer.At a higher pressure of 5.4 MPa,the PVD-TiNTiN-modified die not only maintains a relatively low coefficient of friction but also benefits from TiN-related hard particles formed or retained at the interface.These particles can function as protective third-body constituents,reducing direct metal-to-metal contact and significantly alleviating adhesive wear.Under this high-pressure condition,the overall anti-galling performance of the PVD-TiN surface is superior to that of the nitrided surface.In contrast,the nitrided die under high pressure tends to experience plastic deformation,which generates agglomerated Fe-Cr alloy particles and worsens the interfacial contact state,ultimately destabilizing friction behavior and aggravating wear.In summary,PVD-TiN provides a more pronounced friction-reduction effect than plasma nitriding in the simulated 7075/H13 hot-stamping tribosystem and is particularly suitable for medium-to-low pressure hot-stamping applications where low friction is critical.Plasma nitriding,on the other hand,offers superior structural stability of the modified layer,making it better suited to heavy-load,high-pressure stamping scenarios in which resistance to deformation and long-term surface integrity are essential.

The resharpenability of knife steels is crucial for extending kitchen knife service life, yet the underlying mechanisms governing edge reconstruction during sharpening remain poorly understood. This study investigates the microstructural evolution and surface integrity of 60Cr16MoMA martensitic stainless steel and 60Si2Mn spring steel during simulated honing. Pin specimens were subjected to reciprocating friction against a whetstone for 30 cycles, and the worn surfaces were characterized using SEM, XRD, TEM, and 3D optical profiler. Results show that although 60Cr16MoMA exhibits lower surface roughness after honing process, it develops poorer surface integrity compared to 60Si2Mn. The presence of sub-micron carbides in 60Cr16MoMA hinders uniform material removal during sharpening, causing preferential matrix wear and carbide-induced surface protrusions that compromise edge geometry. In contrast, 60Si2Mn achieves more uniform material removal despite developing higher surface roughness, maintaining better edge integrity. These findings provide mechanistic insights into why carbon/spring steels are empirically easier to sharpen than martensitic stainless steels, offering guidance for knife material selection.

N80 steel pipes, commonly used in the oil and gas industries, are susceptible to corrosion in marine environments. This study investigates the influence of lanthanum and cerium elements on the corrosion behaviour of N80 steel at open circuit potential using in-situ micro-Raman spectroscopy and optical microscopy. Over a 9-day immersion period, N80RE initially exhibited higher but ultimately lower corrosion rates compared to N80, with a 15% reduction in corrosion rates at later stages. In-situ Raman measurements revealed the formation of hematite on N80 and its absence on N80RE within the first 0.25 days, potentially due to the pH-buffering effect of rare earth elements. Differences in the percentages of rust phases were observed between in-situ and ex-situ measurements, highlighting the importance for in-situ testing under service conditions.

This study deals mainly with the influence of adhesive layer on the fatigue behavior and fretting of self-piercing riveted (SPR) joint joining differing thicknesses of AlSi10MnMg aluminum and DP590 steel sheets in lap shear geometry. Fatigue life, failure modes, crack propagation and fretting behaviors of the SPR and SPR-bonded joints were investigated and compared. The results showed that the static strength and fatigue life of SPR-bonded joints were significantly enhanced than that of SPR joints, but the fatigue failure mode of SPR-bonded and SPR joints differed. The SPR-bonded joints all failed in a rivet tail pull-out mode at all tested loads, which accompanied with small cracking in the aluminum sheet in contact with the rivet tail at lower test load. However, the failure mode of the SPR joints shifted from the aluminum sheet cracking to rivet tail pull-out as the fatigue test load increased. And during the aluminum sheet cracking failure, the fatigue crack originated from the faying interface of aluminum and steel sheet at the vicinity of the rivet shank and propagated along the width direction of aluminum sheet. Fretting wear analysis showed that the overall extent of fretting decreased and the location of fretting areas varied due to the adhesive bonding. Fretting of SPR joints mostly existed at the faying interface between aluminum and steel about 1.5 mm away from the rivet shank and resulted in fatigue crack initiation, while the fretting region of SPR-bonded joints shifted to the faying interface between rivet tail and aluminum sheet.

The effect of rare earth elements La and Ce on the corrosion behaviour of steel rebar HRB400E with mill scale was investigated in detail using electrochemical measurements and numerous characterization techniques after salt spray testing with NaCl. The results indicated that addition of La and Ce could decrease the corrosion rates of HRB400RE by more than 50 %. At the initial stages of corrosion, corrosion products on HRB400ERE were observed only on the exterior of the mill scale, with a relatively high percentage of magnetite and hematite. On the contrary, corrosion products were present on both the exterior and interior of the mill scale on HRB400ERE. During the corrosion process, the protective index of the rust on HRB400ERE was consistently higher than that on HRB400E. The dense and protective mill scale and rust layers formed on HRB400ERE both contributed to the enhanced corrosion resistance of the RE-alloyed steel.

The hydrogen embrittlement (HE) susceptibility of ultra-high strength fastener steels is a critical factor for their practical applications. To explore the influence of microstructure on HE for 1400 MPa grade fastener steel, two heat treatment processes, austempering and quenching and tempering (QT), were carried out for 42CrMoVNb steel. The microstructures were observed and analyzed by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). Slow strain rate test (SSRT) revealed that the austempered 42CrMoVNb steel exhibited significantly superior resistance to HE compared with the tempered condition. The microstructure of the austempered steel consisted of lower bainite and martensite, with carbides distributed within the bainite laths and absent at the original austenite grain boundaries. Additionally, the lower dislocation density in this microstructure further enhances its resistance to HE. These findings suggest that austempering treatment can effectively reduce the HE susceptibility of ultra-high strength fastener steels while maintaining the required strength level of fasteners.

To understand the corrosion mechanisms of rail steels, immersion tests were conducted on U71Mn rail steels produced in 1994 and 2021. It was observed that, at the onset of corrosion, only matrix near clustered MnS inclusions dissolved. Further characterization revealed that this was due to the combined effects of lower Volta potential, higher lattice distortion of the surrounding matrix, and strip-shaped carbides in the surrounding matrix induced by the clustered distribution of MnS. Consequently, the U71Mn2021 rail steel, with fewer MnS clusters formed, exhibited better corrosion resistance, as evidenced with electrochemical measurements. These findings suggest that refined processing techniques to control inclusion formation could be effective methods for developing U71Mn rail steels with greater corrosion resistance.

The oxygen content of M2 high-speed steel has not been intentionally controlled in industrial production through secondary refinement in vacuum furnaces. However, a lower oxygen content has a significant effect on the cleanliness, toughness, and addition of rare-earth elements to M2 high-speed steel. The changes in total oxygen content controlled by vacuum carbon deoxidation (VCD) treatment and inclusion evolution were investigated in M2 high-speed steel to understand the effects of carbon on dissolved oxygen and oxides in the carbon–oxygen (C-O) reaction process. Furthermore, the microstructure and properties of M2 high-speed steel caused by vacuum insulation and the role of reducing oxygen content in rare-earth alloying were briefly demonstrated. The results showed that the [O%] decreased from 30 ppm to 3 ppm in a vacuum at holding times above 25 min through the C-O reaction, leading to an inclusion reduction of approximately 70%. In the case of [O%] = 3 ppm in M2 high-speed steel, the addition of rare-earth elements has a greater effect on the inclusion characteristics. Lowering the oxygen content of M2 high-speed steel improves cleanliness and plays a significant role in rare-earth alloying.

Conventional powder metallurgy techniques fail to meet the demands for ultrahigh purity tungsten (UHPW) and scalable component sizes required by the semiconductor industry. In this study, ultrahigh purity (99.999998 wt %) large-size tungsten parts, with an adjustable thickness and a diameter of 350 mm, were prepared via a chemical vapor deposition (CVD) method using ultrahigh purity (99.9999 wt %) tungsten hexafluoride (WF6) as the precursor. The microstructure and physical properties of the resulting CVD-UHPW were evaluated and compared with those of powder metallurgy tungsten (PM-W). The results indicate that CVD-UHPW displays a columnar grain microstructure with a lower dislocation density and internal strain, whereas PM-W shows an equiaxed grain microstructure. CVD-UHPW has a density of 19.17 g/cm(3), closely matching the theoretical density of tungsten (19.35 g/cm(3)) and significantly higher than PM-W's density of 18.79 g/cm(3). The specific heat capacities of CVD-UHPW, measured from 298 to 1473 K, range from 0.113 to 0.146 J/gK, similar to PM-W's range of 0.120 to 0.151 J/gK. CVD-UHPW shows improved electrical and thermal conductivities compared to PM-W, with values ranging from 1.68 x 10(6) to 1.78 x 10(7) S/m and 105.7 to 196.4 W/(mK) from 298 to 1473 K. This study highlights the potential of the CVD method for the large-scale production of ultrahigh purity tungsten parts, emphasizing its significant applicability across various industries.

The effects of rare earth elements (REEs) on the corrosion behavior of weathering steels under a simulated immersion environment and a real atmospheric environment have been investigated in this paper. Although the corrosion rate of the indoor accelerated corrosion experiment (0.01 mol/L NaHSO3) is much higher than that of the real atmospheric exposure experiment, the addition of REEs can highly improve the corrosion resistance of test steels under both conditions. The improvement of the corrosion resistance can be attributed to the quick transformation of gamma-FeOOH into alpha-FeOOH and the accelerated formation of a stable rust layer by REEs. Furthermore, the segregation of the REE inner rust layer increases the density of the rust layer and prevents corrosive particles from eroding the matrix. REEs can also promote the segregation of Cu, Cr, and other alloying elements in the rust layer, thus blocking the cracks and holes and enabling the formation of a continuous rust layer with good adhesion. Rare earth elements (REEs) highly improved the corrosion resistance of weathering steels by promoting quick transformation from gamma-FeOOH into alpha-FeOOH and accelerating the formation of stable rust layers. The segregation of REE and Cu/Cr inner rust layers blocked cracks and prevented corrosive particles from eroding. image

Fe–Mn–Al–C low-density steels are regarded as promising materials applied in the automotive industry to achieve the minimization of vehicular emissions and fuel consumption. This study investigates the high-temperature strength and hot ductility of Fe–22Mn–9Al–0.6C low-density steel through high-temperature tensile tests at 800–950 °C. The high-temperature strength decreases with an increasing deformation temperature. This indicates that the precipitation of B2 reduces the hot ductility during the hot deformation of steel, where the results are consistent with those during the solid-solution treatment at 800–950 °C with a holding time of 0.5 h. Furthermore, at 800 °C the γ transforms into a mixture of α + DO3 and κ-carbide precipitates. A transformation of κ + DO3→B2 occurs in the temperature range of 850–900 °C, and at this point the κ-carbide dissolves into the matrix and B2 is generated, resulting in a significant decrease in hot ductility. As the temperature increases up to 950 °C, B2 emerges and transforms into the δ phase, and the κ-carbide precipitates along the γ/γ grain boundaries. The precipitation of B2 during high-temperature treatments in Fe-Mn-Al-C low-density steels is the critical factor affecting hot ductility, leading to crack generation; therefore, it is extremely essential to prevent the temperature interval of B2 precipitation during hot deformation processes.

In this study, the corrosion behavior of typical nonmetallic inclusions in rebars HRB400E alloyed with rare earth (RE) was investigated using scanning electron microscopy-energy-dispersive spectroscopy, scanning Kelvin probe force microscopy, and Pourbaix diagram. The results showed that the presence of micro-crevice affected the stability of MnS inclusions and the surrounding matrix. The corrosion process of MnS inclusions with micro-crevice was influenced by crevice corrosion, while MnS inclusions without micro-crevice exhibited comparatively good corrosion resistance. In addition, the dissolution of inclusions was also strongly affected by the chemical compositions, and the presence of RE elements (La and Ce) can improve the stability of the inclusions. Mechanism of the localized corrosion process induced by typical nonmetallic inclusions in rebars alloyed with RE in 2 wt.

The martensitic stainless cutlery steel is frequently exposed to conditions where there were both wear and corrosion in the daily usage of kitchen cutlery. To understand the degradation mechanism of the cutlery steel under practical application environments, tribocorrosion tests were performed on 60Cr16MoMA martensitic stainless steel (MSS) in 3.5 wt% NaCl solution and pressed Shanghai Bok Choy (pSBC). The results revealed that compared with 3.5 wt% NaCl solution, the 60Cr16MoMA steel exhibited better tribocorrosion resistance in pSBC during sliding. Through analysis of cross-sectional wear track profiles, it was found that the 60Cr16MoMA steel had the least volume loss when tested in pSBC. High performance liquid chromatography-mass spectrometry results showed that flavonoids and ascorbic acid were present in pSBC, which may act as corrosion inhibitors and stabilize the passive film through physisorption or chemisorption. X-ray photoelectron spectrometer results further confirmed that the passive film formed in pSBC was more stable due to higher Fe2+/Fe3+ and Cr2O3/Cr(OH)3 ratios. These findings further confirm the MSS are subjected to the hazards of wear, corrosion and tribocorrosion, and provide important empirical and theoretical support for evaluating cutlery steel volume loss in practical application environments in the future.

The effect of spheroidizing annealing on carbide characteristic parameters, mechanical properties and wear resistance of the quenching and tempering (Q&T) high carbon martensitic stainless steel is investigated. The microstructure of the steel is characterized and analyzed through various techniques, including scanning electron microscope (SEM), X‐ray diffraction (XRD), electron backscattering diffraction (EBSD), and transmission electron microscope (TEM). Results show that the microstructure of the annealing steel is mainly composed of ferrite and M23C6 carbide. With the rise of austenitizing temperature, the average diameter of carbide of the annealed steel increases. The average diameter of carbides in the Q&T steel changes in the same way as that observed in the annealed steel. The steel has the lowest annealing hardness, highest Q&T toughness, and wear resistance at an annealed soaking temperature of 860 °C. The influence factor of the toughness and wear resistance can be identified that small‐sized carbides and low angle grain boundaries exhibit strong interface adhesive strength. This reduces the probability of cracking in the particle or at the interface.