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The design of high performance structural materials is always pursuing combinations of excellent yet often mutually exclusive properties such as mechanical strength, ductility and thermal stability. Although crystal-glass composite alloys provide better ductility compared to fully amorphous alloys, their thermal stability is poor, due to heterogeneous nucleation at the crystal-glass interface. Here we present a new strategy to develop thermally stable, ultrastrong and deformable crystal-glass nanocomposites through a thermodynamically guided alloy design approach, which mimics the mutual stabilization principle known from symbiotic ecosystems. We realized this in form of a model Cr-Co-Ni (crystalline)/Ti-Zr-Nb-Hf-Cr-Co-Ni (amorphous) laminate composite alloy. The symbiotic alloy has an ultrahigh compressive yield strength of 3.6 GPa and large homogeneous deformation of ∼15% strain at ambient temperature, values which surpass those of conventional metallic glasses and nanolaminate alloys. Furthermore, the alloy exhibits ∼200 K higher crystallization temperature (TX > 973 K) compared to that of the original TiZrNbHf-based amorphous phase. The elemental partitioning among adjacent amorphous and crystalline phases leads to their mutual thermodynamic and mechanical stabilization, opening up a new symbiotic approach for stable, strong and ductile materials.

Wear-related energy and material loss cost over 2500 Billion Euro per year. Traditional wisdom suggests that high-strength materials reveal low wear rates, yet, their plastic deformation mechanisms also influence their wear performance. High strength and homogeneous deformation behavior, which allow accommodating plastic strain without cracking or localized brittle fracture, are crucial for developing wear-resistant metals. Here, we present an approach to achieve superior wear resistance via in-situ formation of a strong and deformable oxide nanocomposite surface during wear, by reaction of the metal surface with its oxidative environment, a principle that we refer to as ‘reactive wear protection’. We design a TiNbZr-Ag alloy that forms an amorphous-crystalline oxidic nanocomposite surface layer upon dry sliding. The strong (2.4 GPa yield strength) and deformable (homogeneous deformation to 20% strain) nanocomposite surface reduces the wear rate of the TiNbZr-Ag alloy by an order of magnitude. The reactive wear protection strategy offers a pathway for designing ultra-wear resistant alloys, where otherwise brittle oxides are turned to be strong and deformable for improving wear resistance., Wear-resistant metals have long been a pursuit of reducing wear-related energy and material loss. Here the authors present the ‘reactive wear protection’ strategy via friction-induced in situ formation of strong and deformable oxide nanocomposites on a surface.

The continuous energy input can lead to heat accumulation in the multi-pass lap laser cladding, which results in a progressive increase in the dilution rate and deteriorates the quality of laser cladding. Precisely controlling the stability of the dilution in the multi-pass laser cladding is still challenging. In this study, we proposed a deep-learning driven method for precisely controlling the dilution rate in the multi-pass laser cladding. Initially, the relationship between the dilution rate and power energy is retracted via the experiment-based finite element simulation. Subsequently, the convolution neural network deep learning is applied to optimise and improve the accuracy of the dilution rates in the cladding layer. The experiment verifies that the high stability of dilution rate in each pass, i.e. average errors of less than 10.88%, is achieved via in-situ adjusting of the power energy using the prediction obtained from the proposed method. We also attempted to provide insights into the dilution mechanism in Invar alloy multi-pass laser cladding as well as the potential applications of this method for other materials in the cladding and other 3D metal additive manufacturing.

Background: This study was performed to identify the alterations of Long non-coding RNAs (lncRNAs) induced by oxidative stress and investigate the functional roles of SNHG16 in the pathological angiogenesis by human retinal microvascular endothelial cells (HMRECs). Methods: The expression profiles of lncRNAs and mRNAs induced by oxidative stress were identified by RNA-Seq, and the dysregulation of 16 lncRNAs including SNHG16 was verified in H2O2-treated human umbilical vein endothelial cells (HUVECs). Luciferase reporter assay and RIP analysis were used to investigate the binding relationship of SNHG16 to miR-195. Results: We confirmed that over-expression of SNGH16 attenuated H2O2-induced angiogenesis by HMRECs. In addition, SNHG16 was significantly decreased, whereas miR-195, a predictive target of SNHG16, was upregulated in H2O2, HG, and AGE-treated HMRECs. The binding relationship of SNHG16 to miR-195 was subsequently verified by luciferase reporter assay and RIP analysis. SNHG16 cotransfection abolished miR-195-mediated repression on mitofusin 2 (mfn2) protein level and counteracted the inductive effect of miR-195 on angiogenesis by HMRECs. Conclusion: These results indicated that decreased SNHG16 accelerates oxidative stress-induced pathological angiogenesis in HMRECs by regulating the miR-195/mfn2 axis, providing a potential target for diabetic retinopathy (DR) therapy.

In this paper, oil-in-water (O/W) based nanolubricants containing TiO2 nanoparticles were developed to reduce the rolling force and improve the surface quality of rolled 304 stainless steel product. Practical hot rolling tests with and without application of lubricant were conducted to systematically investigate the effects of the developed O/W based nanolubricants on the rolling force, surface roughness, oxide scale thickness and tribological behaviour. The obtained results indicate that the nanoparticles can enter the deform zone with oil droplets to take a lubrication effect. The optimal lubrication effect can be achieved when the O/W (1% oil mass fraction) based nanolubricant with a TiO2 mass fraction of 1.5% was applied. The microstructure of oxide scales formed on the hot rolled sample was not significantly affected by TiO2 nanoparticles in the O/W based lubricant, but the oxide scale growth could be induced by TiO2 nanoparticles. A discontinuous thin SiO2 layer at the substrate-scale interface was observed. It can effectively reduce the formation of iron-rich oxides. The novel nanolubricant has a great potential to be applied in the hot steel rolling, to realise the cost-effective and environmental-friendly manufacturing process.

Oil-in-water (O/W) based nanolubricants have the potential to improve the stability of O/W emulsion system and reduce friction, thereby enhancing the efficiency of the lubrication. In this paper, the stability, dispersibility and tribological properties of O/W based nanolubricants with varying mass fractions of oil and TiO 2 nanoparticles were investigated. The results show that nanolubricants have good dispersibility and stability. The coefficient of friction (COF) is reduced by 16.3% with the addition of 2.0% TiO 2 nanoparticles to the O/W lubricant (1.0% oil). The lubrication mechanism of the O/W based nanolubricants with addition of TiO 2 nanoparticles is proposed. The nanoparticles existing in the oil pool can enter the contact area to significantly reduce the COF and increase the weight loss. Increased COF will be induced due to aggregation of nanoparticles around the oil pool.

The tribological behaviour of innovative TiO 2 nano-additive water-based lubricant on ferritic stainless steel (FSS) 445 was characterised on a ball-on-disk tribometer. Non-oxidised (clean) and pre-oxidised FSS 445 disks with original rough surfaces were both applied in the tribological tests at room temperature. The results show that the water-based nanolubricants with concentrations of 0.4–8.0 wt% TiO 2 can significantly reduce the coefficient of friction (COF) on the two types of disks. The 4.0 wt% TiO 2 lubricant exhibits optimal tribological properties, including the lowest COF and the strongest anti-wear ability on the applied balls under all lubrication conditions. The lubrication mechanisms are primarily ascribed to the formation of tribofilm and the ball-bearing effect of the TiO 2 nanoparticles, respectively, on the two different disks.

As the strip thickness is in the range of sub-millimetre in micro flexible rolling, springback ratio in thickness direction has a significant impact on product quality, which is influenced by various process parameters during forming process. This paper focuses on performing a numerical and experimental investigation to evaluate the effects of initial strip thickness, friction coefficient and rolling speed on the springback ratio in thickness direction during the micro flexible rolling process with reductions of 20 to 50% using orthogonal trial design, and wherein the three-level factors orthogonal array is chosen and nine representative orthogonal trials for each reduction have been implemented. With the significance of each process parameter for each reduction identified by variance analysis, an optimum proposal for each reduction to obtain the minimum springback ratio has been determined numerically, which is afterwards confirmed by experimental data. Moreover, a qualitative estimate of the influences of process parameters on the rolling force, as well as a quantitative analysis of the relationship between the length of thickness transition zone and the parameter level have also been carried out with reference to the obtained results.

In this work, the effects of the developed oil-in-water (O/W) based nanolubricants containing TiO2 nanoparticles (NPs) on the tribological behaviour of oxidised high-speed steel (HSS) were studied, using pin-on-disc tests. The pin was made of HSS and, prior to the wear test, was oxidised to form a scale layer on the surface. The results show that the TiO2 NPs in the O/W lubricant can achieve an excellent reduction of the coefficient of friction (COF) and improve the anti-wear properties of pins with oxidised surfaces. The TiO2 NPs in the nanolubricant were found to have the filling and tribo-sintering effects. The NP aggregation around the contact area was observed with higher TiO2 NP concentrations in the nanolubricant, revealing a larger NP aggregation area. Based on the results and analysis, the mechanism about the effects of the TiO2 NPs in the O/W based nanolubricant on the wear and COF were well explained.

Hot rolling tests of microalloyed steel were performed at rolling temperatures of 1050, 950, and 850 °C under different lubrication conditions, including dry, water lubrication, and 1.0 vol.% oil-in-water (O/W) emulsion. The rolling force, surface roughness, and thickness of the oxide scale of the rolled steel were investigated in order to evaluate the lubrication effects of TiO2 nano-additive water-based lubricants. The results show that the rolling force under a rolling temperature of 1050 °C does not vary significantly under all the lubrication conditions. The 4.0 wt.% TiO2 water-based lubricant, however, leads to the lowest rolling force at rolling temperatures of 950 and 850 °C. The application of 4.0 wt.% TiO2 water-based lubricant in hot rolling not only produces the best surface finish, but also results in the thinnest oxide scale of the rolled steels. The lubrication mechanisms of TiO2 nano-additive water-based lubricants in hot rolling were also discussed.

A ball-on-disk tribometer was employed to evaluate the lubrication performance and mechanisms of innovative TiO 2 nano-additive water-based lubricants. Two experimental methods were applied to determine the optimal mass fraction of TiO 2 . In the method I, lubricants were added onto the worn disk tracks at a predetermined time interval. In the method II, the disks were immersed in the lubricants continuously during the whole process of tribological tests. The results both indicate that the water-based lubricants can significantly reduce the coefficient of friction (COF). The 0.8 wt% TiO 2 lubricant demonstrates excellent tribological properties including the lowest COF and the strongest wear resistance under all lubrication conditions. The lubrication mechanisms are attributed to the rolling and mending effects of the TiO 2 nanoparticles.

Some defects on the surface of carbon steel do not need to be removed before hot rolling because the surface will be vigorously oxidised in a reheating environment. Thus the defects can be minimised by oxidising and then removed by the de-scaling process. The defects on the surface of ferritic stainless steels, however, are not easily removed by oxidation when a high chromium concentration is used. In this paper, a ferritic stainless steel grade 445 was selected as a research material. The effects of different surface features on oxidation and tribological behaviour in the hot rolling process were investigated. Three surface states were prepared, namely, smooth surface, surface with 45° grinding marks and surface with oscillation marks. The samples were put into an electric furnace at 1100 °C for reheating. Hot rolling tests were carried out on a 2-high Hille 100 experimental rolling mill. Rolling forces were measured, and the coefficient of friction was calculated and compared under various rolling parameters. It was found that the original surface profiles with grinding marks were still maintained during oxidation. The original oxide scale on the surface with oscillation marks caused the formation of irregular oxide nodules and the spallation of the oxide scale. Surface morphology and the reduction in thickness had a significant impact on the oxide scale integrity and coefficient of friction in the hot rolling process.

Alzheimer's disease (AD) and cancer have inverse relationship in many aspects. Some tumor suppressors, including miR‐34c, are decreased in cancer but increased in AD. The upstream regulatory pathways and the downstream mechanisms of miR‐34c in AD remain to be investigated. The expression of miR‐34c was detected by RT–qPCR in oxidative stressed neurons, hippocampus of SAMP8 mice, or serum of patients with amnestic mild cognitive impairment (aMCI). Dual luciferase assay was performed to confirm the binding sites of miR‐34c in its target mRNA. The Morris water maze (MWM) was used to evaluate learning and memory in SAMP8 mice administrated with miR‐34c antagomir (AM34c). Golgi staining was used to evaluate the synaptic function and structure. The dramatically increased miR‐34c was mediated by ROS‐JNK‐p53 pathway and negatively regulated synaptotagmin 1 (SYT1) expression by targeting the 3′‐untranslated region (3′‐UTR) of syt1 in AD. The expression of SYT1 protein was reduced by over expression of miR‐34c in the HT‐22 cells and vice versa. Administration of AM34c by the third ventricle injection or intranasal delivery markedly increased the brain levels of SYT1 and ameliorated the cognitive function in SAMP8 mice. The serum miR‐34c was significantly increased in patients with aMCI and might be a predictive biomarker for diagnosis of aMCI. These results indicated that increased miR‐34c mediated synaptic and memory deficits by targeting SYT1 through ROS‐JNK‐p53 pathway and the miR‐34c/SYT1 pathway could be considered as a promising novel therapeutic target for patients with AD., miR‐34c mediated synaptic plasticity deficits by targeting SYT1 through ROS‐JNK‐p53 pathway in response to oxidative stress and participated in the pathogenesis of AD.

The indentation-induced plasticity and roughness have been investigated intensively by experiments and simulations during the last decades. However, the precise mechanisms of how dislocation flow leads to pile-up formation are still not completely understood, although this is one of the initial steps causing surface roughening in tribological contacts at low loads. In this work, $$\{001\}$${001}-, $$\{101\}$${101}- and $$\{111\}$${111}-grain orientations in an austenite stainless steel [(face-centered cubic (FCC) phase]) are indented with varying load forces. By using scanning electron-based methods and slip plane analysis, we reveal: (1) how slip-steps show the change of pile-up formation, (2) how the slip-plane inclination determines the dislocation flow and (3) how slip-plane interactions result in the final pile-up shape during indentation. We find that the flow direction transforms from the forward flow to the sideway at a transition angle of $$55^\circ{-}58^\circ $$55∘-58∘ between the slip-plane and the surface. We use large displacement finite element method simulations to validate an inversion of the resolved shear stress at this transition angle. We provide insights into the evolution of plasticity in dislocation-mediated FCC metal indentations, with the potential application of this information for indentation simulations and for understanding the initial stage of scratching during tribology in the future.

Oxide scale formed on the steel surface during hot rolling affects the tribological property of nanoTiO2 additive oil-in-water (O/W) lubricant, resulting in changes of roll forces, torques and power consumption, as well as the wear and the surface quality of the work roll and workpiece in hot rolling. The nanoparticle additive O/W emulsion is a novel lubricant and has a great potential to be used in hot rolling process. However, little research has focused on the nanoparticle additive O/W emulsion. In this study, oxidation, tribological and hot rolling tests were conducted to investigate the tribological behaviour of nanoTiO2 additive O/W lubricant. The results indicate that the surface morphology of the oxide scale plays an important role in tribological behaviour of nanoTiO2 additive O/W lubricants. The coefficient of friction (COF) and rolling force are reduced with the addition of nanoTiO2 particles into the 1.0% (mass %, oil concentration) O/W lubricant. This study is helpful in applying the nanoTiO2 additive O/W lubricant during hot rolling to realise reduction of rolling force and power consumption.

Contact angle and scratch tests have been conducted to investigate the effects of nano-TiO2 additive in oil-in-water (O/W) lubricant. The results show that the contact angle between high-speed steel with oxide scale and 1% (oil concentration) O/W lubricant decreases first and then increases as the concentration of nano-TiO2 particle in the O/W lubricant increases. The smallest contact angle is obtained after an addition of 4% nano-TiO2 additive to the O/W lubricant. This is because the nano-TiO2 can enhance the surface excess of the oil when the nano-TiO2 particles distribute throughout the surface of the oil droplets, and after saturation they can distribute throughout the water and also improve the surface excess of the water in the O/W lubricant. The scratch and hot rolling tests show that the nano-TiO2 particles in the O/W lubricant can also reduce friction, improve scratch resistance, and reduce rolling force. A method for measuring the adhesion force of the oxide scale is proposed and the ef...

To obtain a low cost, environmentally friendly and effective lubricant, a novel nanoTiO2 additive oil-in-water (O/W) lubricant for hot steel rolling has been developed. Based on the contact angle, tribological and hot rolling tests, the performance of the nanoTiO2 additive O/W lubricants was evaluated and discussed. The results show that the strongest adhesion force between the nanoTiO2 additive O/W lubricant and the work roll is obtained after addition of 4% nanoTiO2 additive in the 1% O/W lubricant. The nanoTiO2 nanoparticles can reduce coefficient of friction (COF) and rolling force, and enhance the surface quality of the hot-rolled product. The lubrication mechanism of nanoTiO2 additive O/W-based lubricant has been proposed.

Improving the wear properties requires an understanding of the mechanisms during the initial stages of wear. This paper focuses on the transition from static indentation to dynamic wear, i.e. the evolution from stationary to sliding contact. By using single micrometer-sized roughness peaks on copper, cementite and austenitic steel, we observe that the conservation of contact area, elastic recovery, and the front pile-up development are the dominant mechanisms. The elastic recovery leads to an additional contact area at the backside of the asperity. The influence of the crystallographic orientation was found to be negligible during the initial increase in wear depth but significant during the later stages. Moreover, the partial wear depth recovery is observed only in ductile materials.

High-entropy alloys (HEAs) and metallic glasses (MGs) are two material classes based on the massive mixing of multiple-principal elements. HEAs are single or multiphase crystalline solid solutions with high ductility. MGs with amorphous structure have superior strength but usually poor ductility. Here, the stacking fault energy in the high-entropy nanotwinned crystalline phase and the glass-forming-ability in the MG phase of the same material are controlled, realizing a novel nanocomposite with near theoretical yield strength (G/24, where G is the shear modulus of a material) and homogeneous plastic strain above 45% in compression. The mutually compatible flow behavior of the MG phase and the dislocation flux in the crystals enable homogeneous plastic co-deformation of the two regions. This crystal-glass high-entropy nanocomposite design concept provides a new approach to developing advanced materials with an outstanding combination of strength and ductility.

Engineering surfaces consist of microasperities, which result in plasticity during the run-in of the tribological system. A fundamental insight of the plastic flow during single asperity wear at the microscale is required to thoroughly understand tribology induced microstructure at the macroscale and to tailor future metal surfaces. In this work, we indent and wear {001}-, {101}- and {111}-grains in an austenite stainless steel. The transition from indentation to ploughing and the evolution of plasticity during ploughing is addressed. We find that slip-step and pile-up evolution during the indentation segment of the wear experiment influence the plasticity during the ploughing segment that follows upon the indentation. We conclude that the pile-up evolution dominates the development of the friction force during ploughing at the microscale.

Rolling is the process of reducing the thickness or changing the cross section of a workpiece by compressive forces applied through a set of rolls. This article emphasizes flat rolling and illustrates basic flat-rolling process used to reduce the thickness of a rectangular cross section. It provides a discussion on hot rolling, cold rolling, and warm rolling, as well as lubrication in rolling. The article reviews the lubrication for iron-base and nickel-base materials, light metals, copper-base alloys, and titanium alloys. It discusses the wear mechanism in rolling: abrasion, adhesion, and fatigue, as well as oxidative and corrosive wear. Surface modification techniques, such as hardening by induction heat treating, weld overlay, thermal spray coating, coating via physical vapor deposition (PVD), and laser surface treatment, are also discussed for improving roll service life.

The newly designed high performance tested steel was prepared by the process of vacuum induction furnace smelting and forging. According to the ideas of online relaxation and quenching-intercritical quenching-tempering (Q-L-T) process, effects of offline relaxation process on microstructure and mechanical properties of the tested steel were investigated. Offline relaxation process was simulated using the MMS-300 thermal simulation testing apparatus and heat treating furnace. The results show that the microstructures are composed of bainite and martensite when the specimens are quenched in the austenite region. Once the specimens are air-cooled into the dual phase region, ferrite and granular bainite start to form. In the relaxation process, fine Nb(C, N) carbonitrides are precipitated first and then grow and coarsen. The microstructure is affected by process and determines mechanical properties. The Vickers hardness and yield strength (YS) first rise then fall when the relaxation temperature drops in austenite region, and then decline dramatically in dual phase region. When the relaxation time is 20 s, the tensile strength reaches the peak (1034 MPa), and at that time YS is 872 MPa, longation is 17. 7% and Charpy V-notch impact energy is 171 J at — 20 °C. When the relaxation time increases to 100 s, the yield and tensile strengths are 750 and 934 MPa respectively, elongation is 18. 6% and Charpy V-notch impact energy is 165 J at – 20 °C.