Mechanical and tribo-metallurgical behavior of 17-4 precipitation hardening stainless steel affected by severe cold plastic deformation: a comprehensive review article

This article comprehensively reviews the mechanical properties and tribo-metallurgical behavior of 17-4 precipitation hardening stainless steel (17-4PH SS) during and after cold plastic deformation. Referring to the scientific literature, stainless steels are one of the few types of ferrous alloys which could be appropriately set up through cold working processes in the forms of sheets or other shapes. Likewise, some other metal alloys such as mild low-carbon-based steels, copper and its alloys, aluminum alloys, and some others are the few types of metal alloys which have this capability. On the other hand, in engineering applications, there are several types of mechanical failures, which must be taken into account to investigate the mechanical behavior and tribo-metallurgical properties of any targeted materials. For example, corrosion resistance, wear resistance, and fatigue failure are investigated according to the microstructural studies, comprising of the grain size, grain boundaries, orientations, dislocations, and so on. Based on the published results, focusing on 17-4PH SS, one of the most main effective factors on mechanical and tribo-metallurgical performance is the grain size. Also, the favorable balance of two mechanical properties of strength and ductility has been reported as a dilemma in the materials science, and the problem delineates upon the limitations of numerous structural materials potentials. Following the failure analysis of the materials, in order to diminish the damages caused by fretting fatigue some methods such as ultrasonic processes are applied for the treatment of 17-4PH SS via changing the microstructure, residual stress, and other parameters. Also, through the other cold deformation technologies, the nanostructured surface layer with highly upgraded mechanical properties of several ultrasonic surface rolling process-treated 17-4PH SS has been obtained. To this end, such cold working processes on 17-4PH SS and their subsequent results are elaborated in this review paper. Graphical abstract: [Figure not available: see fulltext.

Conformal and continuous deposition of bifunctional cobalt phosphide layers on p-silicon nanowire arrays for improved solar hydrogen evolution

Vertically aligned p-silicon nanowire (SiNW) arrays have been extensively investigated in recent years as promising photocathodes for solar-driven hydrogen evolution. However, the fabrication of SiNW photocathodes with both high photoelectrocatalytic activity and long-term operational stability using a simple and affordable approach is a challenging task. Herein, we report conformal and continuous deposition of a di-cobalt phosphide (Co2P) layer on lithography-patterned highly ordered SiNW arrays via a cost-effective drop-casting method followed by a low-temperature phosphorization treatment. The as-deposited Co2P layer consists of crystalline nanoparticles and has an intimate contact with SiNWs, forming a well-defined SiNW@Co2P core/shell nanostructure. The conformal and continuous Co2P layer functions as a highly efficient catalyst capable of substantially improving the photoelectrocatalytic activity for the hydrogen evolution reaction (HER) and effectively passivates the SiNWs to protect them from photo-oxidation, thus prolonging the lifetime of the electrode. As a consequence, the SiNW@Co2P photocathode with an optimized Co2P layer thickness exhibits a high photocurrent density of -21.9 mA.cm(-2) at 0 V versus reversible hydrogen electrode and excellent operational stability up to 20 h for solar-driven hydrogen evolution, outperforming many nanostructured silicon photocathodes reported in the literature. The combination of passivation and catalytic functions in a single continuous layer represents a promising strategy for designing high-performance semiconductor photoelectrodes for use in solar-driven water splitting, which may simplify fabrication procedures and potentially reduce production costsThis work was funded by ERDF funds through the Portuguese Operational Programme for Competitiveness and Internationalization COMPETE 2020, and national funds through FCT – The Portuguese Foundation for Science and Technology, under the project “PTDC/CTM-ENE/2349/2014” (Grant Agreement No. 016660). The work is also partially funded by the Portugal-China Bilateral Collaborative Programme (FCT/21102/28/12/2016/S). L. F. Liu acknowledges the financial support of the FCT Investigator Grant (IF/01595/2014) and Exploratory Grant (IF/01595/2014/CP1247/CT0001). L. Qiao acknowledges the financial support of the Ministry of Science and Technology of China (Grant Agreement No. 2016YFE0132400).info:eu-repo/semantics/publishedVersio

Microstructural, textural, and residual stress evolution alongside the magnetic properties through isothermal static recrystallization of cold-drawn Fe–Cr–Si–S–C ferritic high-alloy stainless steel and by JMAK modelling

The evolution of microstructures, textures, and residual stresses scale of cold-drawn (CD) 18%Cr ferritic stainless steels (FSS) round bars under isothermal static recrystallization annealing are investigated. As for determination of the new grains' formation, the size, growth, and orientation, as well as the nucleation of grains, alongside revealing the recrystallization fractions are studied by a mixed experimental and theoretical work. The recrystallization kinetics are calculated according to the Johnson-Mehl-Avrami-Kolmogorov theory. Electron backscatter diffraction (EBSD) analyses are applied for the actual specimens of an industrial wire drawing process with 20 and 35% reduction rates. The heat treatment has been implemented at three different set ratio temperatures of 0.65, 0.68, and 0.71, defining as a ratio between the temperatures of annealing and melting point (TRAM). According to the results, the nucleation is occurred at faster incubation time with higher temperature and reduction rate. The grain average size (AGS) increases gradually whereas the temperature increases. This is while the 0.71TRAM-scale annealed samples illustrate finer and more equiaxed recrystallized grains. Following recovery, recrystallized grains, and the grain growth, the overall varied AGS of 27–86 μm in the core region are achieved. Moreover, the JMAK model agrees well with the obtained experimental data. All in all, this 18Cr-FSS material is taken into account for the optimal industrial annealing production as well as the targeted material selection of the market applications. It is observed that the higher recrystallization leads the higher magnetic permeability, lower coercivity, and lower residual stresses compared to the unheated specimens

Viscosity of nanofluids: A review of recent experimental studies

During the past decade, nanotechnology with its rapid development has grabbed the attention of scientists, scholars, and engineers. Nanofluids are one of the surprising outcomes of this technology that could increase the efficiency of thermal systems remarkably. Nanofluids containing solid nanoparticles have a higher viscosity than common working fluids; hence, measuring the viscosity is necessary for designing thermal systems and estimating the required pumping power. In the current review study, an attempt has been made to cover the latest experimental studies performed on the viscosity of nanofluids. An experimental investigation is very vital for the analysis since the theoretical models usually underestimate the nanofluid viscosity. Through experiments, the real effects of volume fraction, temperature, particle size, and shape on the viscosity of nanofluids will be determined

Numerical simulation of dynamic recrystallization behavior of 316L stainless steel under flexible rolling state

With the rapid development of continuous rolling technology, the rigid connection of production equipment-techniques often results in roll wear and frequent shutdowns for roll replacement, which restricts the development of its technical advantages. In this paper, ASTM-316L is used as the experimental steel, based on the numerical simulation technology to carry out the numerical simulation and process optimization research of online roll changing of flexible rolling, comprehensive material high-temperature plastic flow behavior, coupling recrystallization kinetic model embedded in Deform-3D software, to establish a multi-field coupled collaborative control model of online roll changing of flexible rolling, simulating the impact of online roll change on the strip DRX behavior. The results show that the reduction rate of the online roll change, the roll exit speed, the roll input speed, and the deformation temperature have essential effects on the microstructure uniformity of the strip along the thickness direction. Smaller reduction rate, faster roll exit speed, slower roll input speed, and lower deformation temperature are all beneficial to reduce the gradient of DRX volume fraction in the core and surface of the strip and avoid stress concentration and instability. The roll diameter has little effect on the DRX volume fraction gradient at the core and surface of the strip. Therefore, it is necessary to control the online roll changing process of flexible rolling according to the actual rolling process, considering the load of the rolling mill and the mass of the rolls. The research on the recrystallization behavior of online roll changing in this paper can provide a theoretical basis for designing and optimizing the microstructure control of flexible rolling

Amino-functionalized MIL-101(Cr) photodegradation enhancement by sulfur-enriched copper sulfide nanoparticles: An experimental and DFT study

In the present work, a direct Z-scheme composite photocatalyst, NH2-MIL-101(Cr)@CuS, with high photodegradation efficiency of Rhodamine B (RhB) degradation in the visible light spectrum, is fabricated through a solvothermal method. It was found that the NH2-MIL-101(Cr)@CuS composite with an appropriate amount of NH2-MIL-101(Cr) exhibited high catalytic performance in the RhB photodegradation. The photocurrent density and results from the electrochemical impedance spectroscopy (EIS) analysis confirm the promoted photocatalytic activity of the NH2-MIL-101(Cr)@CuS composite compared to the pristine MIL-101(Cr) and CuS nanoparticles, which were supported by the electron lifetime (τn) calculations for the samples. The trapping experiments and Mott-Schottky analysis revealed that the superoxide radicals (radical dotO2−) played an essential role in the photodegradation of RhB and the promoted photocatalytic activity contributed to a direct Z-scheme mechanism between CuS and NH2-MIL-101(Cr). Stability study also shows acceptable results during photocatalytic reaction. Furthermore, Density Functional Theory (DFT) calculations were performed to gain a better understanding of the electronic properties of the NH2-MIL-101(Cr)@CuS nanocomposite. The calculated band structures showed that the nanocomposite has a higher photocatalytic efficiency in the visible region compared to the pristine MIL-101(Cr) and CuS. The calculated band gap of both the semiconductors and the hybrid nanocomposite confirms the experimental results