•A fracture toughness prediction model using the thermal aging constant is proposed.•The aging constant is determined from the tensile data of aged GTAW of 316L.•A simple equation is proposed to ...predict fracture toughness of aged GTAW.•The predicted results agree well with experimental toughness data of aged GTAW.
In this paper, the authors propose a model based on the thermal aging constant to predict the fracture toughness of aged gas-tungsten-arc-welded 316L stainless steel (referred to as GTAW hereinafter). The constant can be determined simply from the tensile data of aged GTAW, and a closed-form expression for this is given. The fracture toughness of aged GTAW can be predicted based on the product of the thermal aging constant with the toughness of unaged GTAW. The predicted toughness agrees well with the experimental data of aged GTAW.
The stainless steel mesh, in the form of the disk, was coated with graphene oxide and poly(dimethylsiloxane) (GO-PDMS) by sol–gel technique. The coated stainless steel meshes are loaded in the ...mini-column as solid-phase extraction cartridge for the fast isolation and preconcentration of polycyclic aromatic hydrocarbons (PAHs) from real water samples. The extracted PAHs (naphthalene, acenaphthene, acenaphthylene, anthracene, benzaanthracene, fluorene, and pyrene) were quantified by gas chromatography-mass spectrometry. The operation parameters affecting the extraction efficiency including sample volume, desorption conditions, and ionic strength were investigated. At optimized conditions, the linearity of this method is obtained from 0.001 to 20 ng mL
−1
with 0.2 to 1.0 pg mL
−1
limit of detection. For 5 replicates at 3 spiking levels (0.1, 1, and 10 ng mL
−1
), the relative standard deviations between 4.0 and 6.3% were achieved. The absolute extraction recovery varied from 89.1 to 94.7%. The enrichment factors were in the range of 2227–2367. The method has been employed in the determination of PAHs in the real water samples including well water, tap water, river water, and wastewater. Relative recoveries are between 95.2 and 100.9%.
Graphical abstract
Schematic representation of the SPE procedure using the self-assembly SPE cartridge
•Combination of nitric acid passivation and specimen position produces open pits.•The open pit specifically develops with a pit “head” and a pit “tail”.•Rupture of salt film and deposition of ...corrosion products are proposed as AE sources.•A three-stage propagation mechanism for pitting corrosion is suggested.
Knowledge gaps exist concerning the acoustic emission (AE) during the pitting corrosion of open morphology. Here, we proposed a simple yet effective strategy to control the pitting evolution uncovered by lacy covers or corrosion products in a vertically positioned 304 stainless steel (304 SS) specimen that was pretreated by immersion in dilute nitric acid. The corrosion pit developed with a “head” and a “tail”, i.e., the open cavity and the corrosion products deposited below the pit head respectively, the evolution of which was monitored with by-stage AE signals. The AE sources associated with the open-morphology of pitting corrosion were discussed.
Selective laser melting has been used to demonstrate the striking effect of laser scanning strategies on the crystalline texture in 316L SS. The aligned crystal orientation along the tensile ...direction (Z-axis) could be varied using the scanning strategy. A strong 〈100〉 single crystalline-like texture is obtained in the direction of the laser scan and a 〈110〉 texture was observed in the build direction when using a bidirectional scan without rotation. Fiber texture was observed along the tensile direction when the bi-directional laser scanning vectors were rotated by 67° (Rot-scan) for each layer. The study highlights a correlation between laser scanning strategies with resulting textures, microstructure, and mechanical properties in as-printed bulk 316L SS. The hardness, Young's modulus, and ultimate tensile strength were significantly influenced by the final microstructure, crystallographic texture, and porosity. Furthermore, the applied laser scanning strategies made it possible to tailor crystallographic textures locally within the component. This was demonstrated by printing characters with a fiber texture, in a matrix with ⟨100⟩ texture parallel to the Z-axis.
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•Laser scanning strategies strongly influence the crystallographic texture in as-printed components.•A ⟨100⟩ single crystalline-like texture is obtained in the direction of laser writing.•Site-specific texture control is achieved by selectively switching laser scanning strategies.
The extensive use of flexible and portable electronic devices stimulates the search for the low-cost and flexible electrodes. Herein, chemically-modified stainless steel mesh derived hematite is used ...as a cost-effective flexible substrate-free anode in lithium ion battery and supercapacitor. This flexible substrate-free electrode exhibits higher potential because it could show excellent contact between active material and current collector during various electrochemical tests. The stainless steel mesh derived hematite also exhibits excellent electrochemical properties, which can be enhanced by further nitridation to achieve optimum storage performance. Thus, this work provides new insight into the development of the cost-effective, scaled up, flexible, substrate-free and multifunctional electrodes.
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•An iron-based composite flexible substrate-free electrode is fabricated.•The substrate-free electrode exhibits excellent rate performance and cyclic life.•The successfully scaled-up electrode and outstanding flexibility prove its potential.
•Tribo-corrosion of stainless steel in molten zinc alloy is studied.•Without wear, Fe2Al5Znx layer forms and protects steel from dramatic corrosion.•The synergy of corrosion and wear accounts for 90 ...% of material loss.•Corrosion induces brittle scale and embrittlement at subsurface, accelerating wear.•Wear promotes formation of less-protective FeZn10 scale, accelerating corrosion.
The failure of 316 stainless steel under tribo-corrosion in molten zinc alloy (Zn-0.2Al, wt%) at 460 °C was investigated and compared with corrosion or the sole wear. In the absence of wear, intact Fe2Al5Znx layer forms and protects the steel from dramatic corrosion. Without liquid-metal corrosion, the steel suffers from plastic deformation on friction and slight adhesive wear. While for tribo-corrosion, the synergy of corrosion and wear accounts for 90 % of material loss. Firstly, corrosion generates a brittle scale and leads to embrittlement at subsurface, which accelerate wear. Secondly, wear promotes the formation of less-protective FeZn10 scale, accelerating corrosion.
The dynamic substructural development and softening mechanism of UNS S32101 duplex stainless steel were comprehensively investigated by employing hot-tensile tests at various strain rates of ...0.1–10 s−1 at a fixed temperature of 1200 °C. Different flow behaviors were attributed to the microstructural evolution and restoration process under various hot-deformation conditions. The alternative restoration mechanisms of ferrite in the current alloy were closely associated with the evolution of the misorientation angle in the (sub)grains, depending on the applied strain rates. Therein, three distinct softening mechanisms were found in ferrite, i) subgrain coalescence (SC) at 0.1 s−1, ii) continuous dynamic recrystallization (CDRX) at 1 s−1 and iii) subgrain rotation-assisted discontinuous dynamic recrystallization (SR-assisted DDRX) at 10 s−1. During SR-assisted DDRX process, new DRX nuclei were preferentially formed at the high-angle grain boundaries/phase boundaries (HAGBs/PBs) through the growth of highly misoriented subgrains. In contrast to ferrite, the available dynamic softening behavior of austenite, unlike the classical DDRX mechanism characterized by strain-induced boundary migration (SIBM), is affected by a limited number of pre-existing HAGBs. At lower strain rates of 0.1 and 1 s−1, the nucleation process of DRX in austenite is analogous to the CDRX behavior, whereas the growth characteristics conform to DDRX, thus, it can be called dynamic recovery-assisted DDRX (DRV-assisted DDRX). At a high strain rate of 10 s−1, DRX nucleation mainly took place through the strain-induced twin boundaries (TBs) transformation into HAGBs, and then rapidly grew via SIBM, referred to as TB-assisted DDRX.
•The fatigue performance of stainless steel bolts under tensile and shear loading is experimentally investigated.•The stress distributions are predicted by refined finite element modelling.•The ...fatigue performance is assessed by various design codes.•Maximum principal stress dominates the fatigue behaviour of bolts with threads in shear plane.•Provisions for shear fatigue are recommended to be modified.
This paper experimentally investigates the fatigue performance of stainless steel bolts in tension and shear under constant-amplitude loading. The static behaviour of normal bolts and Hollo-bolts subjected to monotonic loading was initially reported aiming to obtain the ultimate strength. Periodic loading tests were thereafter performed to acquire tensile and shear fatigue life under various stress ranges in which failure modes and cycles were recorded. From test results, S-N curves were summarised through regression analysis, followed by numerical modelling which was used to investigate the stress distribution. Finally, different design codes were selected to estimate the fatigue limit of bolts in tension and shear. It was found that both coupon tests and monotonic loading tests are required to determine the material property of stainless steel bolts. Regions adjacent to bolt nuts are the most vulnerable parts in terms of fatigue in tension, and the maximum principal stress dominates the fatigue life of fasteners with threads in shear plane. The fatigue strength of Hollo-bolts is slightly higher than that of normal bolts. Moreover, although current design codes can conservatively estimate the fatigue behaviour, provisions for shear fatigue are recommended to be modified for higher accuracy and better application.
•Pit initiation on sensitized Type 304 stainless steel under applied stress were investigated in 4M MgCl2 immersion test.•With and without stress, pitting was initiated at the sulfide/oxide ...inclusions at the sensitized grain boundaries.•The occurrence of pitting increased with applied stress.•Under applied stress, the dissolution of MnS inclusions and sensitized grain boundaries was accelerated.
The effects of applied stress on the pitting of sensitized Type 304 stainless steel were investigated in 4 M MgCl2 immersion test. Regardless of whether stress was applied, pitting was initiated at inclusions at sensitized grain boundaries. In the absence of applied stress, the occurrence of pitting decreased when the area exposed to the solution decreased, and not all the inclusions acted as initiation sites. However, pitting was observed independent of the exposed area under applied stress. The dissolution rates of MnS inclusions and sensitized grain boundaries were accelerated by applied stress.
The present work analyses the effect of harmonic microstructure on the fretting wear behavior of a flat sintered 316L stainless steel sample against a bearing steel ball as well as the mechanism of ...wear. The fretting behavior of the harmonic 316L stainless steel was also compared with a conventional (wrought) and a sintered non-harmonic 316L stainless steel samples. Wear resistance at lower loads (2 and 5 N) was found to be considerably higher for the harmonic 316L stainless steel sample compared to that for the conventional and the sintered non-harmonic 316L stainless steel. Higher wear resistance of the harmonic 316L steel was attributed to harder shell regions distributed in periodic fashion and higher twin boundary/area than those in the coarse grained sample and subsequent engagement of the counter ball with the finer grains. However, with the increase in load, the finer shell region starts getting pulled out due to ploughing action along with the softer core region leading to an increase in coefficient of friction as well wear volume.
•Wear behavior of harmonic, conventional and non-harmonic 316L SS are compared.•Fine and coarse grained regions in harmonic steel show different wear mechanism.•Wear mechanism changes from abrasive at lower load to adhesive at higher loads.•Fine grain and twin boundary lead to better wear resistance in harmonic steel.
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