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Wire arc additive manufacturing (WAAM), based on gas metal arc welding, is ideal for fabricating components with sizeable geometries and moderate structural intricacies. However, the electric arc introduces a heat source and directional heat dissipation during deposition, resulting in undesired microstructural characteristics, such as columnar dendritic structures, which lead to variations in hardness across the printed component. Our previous research introduced the friction stir burnishing (FSB) tool integrated with WAAM using a hybrid approach called simultaneous processing. This method suppressed dendrite formation and enhanced the microstructure within WAAM. This approach directly correlates process dynamics, force dynamics, and temperature control, facilitating efficient plastic deformation. This research investigates the relationship between process parameters and microhardness within the combined manufacturing systems of WAAM and FSB tools. The study primarily focuses on using SUS 316L austenitic stainless steel wire material for WAAM and examines how simultaneous operation with the FSB tool impacts microstructure and microhardness. The investigation emphasizes three key parameters: the distance between the welding torch and the FSB tool, tool rotational speed, and machine feed speed. Comprehensive experimentation, including Taguchi analysis, determines optimal values for these parameters. Results indicate that torch-to-tool distance and machine feed speed significantly influence microhardness, while tool rotational speed shows minimal impact. The most effective combination for enhancing microhardness was a torch-to-tool distance of 20 mm, a machine feed speed of 528 mm/min, and a tool rotational speed of 1900 rpm. This combination induced a plastic deformation transformation effect, contributing to the overall improvement in microhardness. Additionally, the optimal parameters for achieving a smaller grain size were a torch-to-tool distance of 17 mm, a machine feed speed of 356 mm/min, and a tool rotational speed of 1900 rpm, as indicated by the average grain size. Furthermore, this study shows significant improvements in microstructure and hardness within 50–200 µm depth from the surface. Comparative analysis between FSB tool-processed and non-processed samples indicates a 22.51% increase in microhardness, with the grain size of the simultaneous process being 7 µm compared to 11.55 µm. Optimizing the process parameters of simultaneous processing achieves superior microhardness and microstructural refinement. Additionally, it highlights the need for further material development to address challenges associated with tool durability, paving the way for advancements in simultaneous processes. [ABSTRACT FROM AUTHOR]

Tailor weld blank (TWB) is preferred in different components of automobiles to reduce weight of the vehicle. However, TWBs have lower formability than sheets because of increased hardness and strength of weld region. Hence, in this work, detailed formability analysis of TWB of AISI304 is done and compared with as-received sheets along with microstructural correlation. Forming limit diagram for as-received sheet, TWBs are determined. Strain hardening exponent value of as-received sheet is 0.381, unweld region and weld region of TWB is observed to be 0.362 and 0.301, respectively. Numerical simulations were also done for predicting the FLC of TWB of AISI304 with the help of PAM STAMP 2 G solver. TWB showed lower formability than as-received sheets. Similarly, predicted FLD for TWB is almost coinciding with the experimental value. Similarly, optical micro-structure studies were also analysed for as-received sheet, unweld region and weld region of TWB, which showed fully austenitic structure with random grain orientations. At the same time, it was found that strain path chosen for FLD determination has a strong influence on microstructure evolution. [ABSTRACT FROM AUTHOR]

Understanding the impact of high-temperature thermal cycle on coating composition and its corrosion characteristics is essential for coating development. The present study investigated NiCr/TiO2-coated 316L austenitic stainless steel (316L SS) under thermal shock exposure and their corrosion behaviour in 3.5% NaCl solution. The electrochemical parameters were evaluated using potentiodynamic polarisation and electrochemical impedance spectroscopy techniques to understand the corrosion characteristics. Various techniques, viz. field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, were employed to examine the morphology, elemental composition, crystalline and oxidation characteristics of all the samples. The NiCr/TiO2-coated 316L SS demonstrated thermal resistance up to 9-h oxidation period and five thermal cycles. Afterwards, with gradual weight loss, TiO2 spallation appeared on the coated samples. The as-deposited sample revealed an increased pitting potential of 118.76% and improved corrosion resistance over ten times in magnitude than the bare sample. This improvement in the coated sample is attributed to high charge transfer resistance and chemically stable coating layer between the metal matrix and corrosive solution. In contrast, the delaminated sample revealed over four times greater resistance than the bare sample, which is credited to the limited surface area for possible redox reactions and passive NiCr bond coat layer over the metal matrix. [ABSTRACT FROM AUTHOR]

Solid-to-solid diffusion bond between ferritic SA508 low alloy steel (LAS) and austenitic 316L stainless steel (SS) via hot isostatic pressing (HIP) was evaluated. This study investigated the microstructural and mechanical evolutions of the bimetallic interface before and after heat treatment. The interfacial region between two materials demonstrated uniform microstructure, no visible manufacturing defects, and higher interfacial hardness and tensile strength. The joint interface was stronger than for both 316L SS and SA508 LAS. The interfacial hardening was attributed to the significant grain refinement at the interface region and dislocation hardening under as-HIP'ed condition. Post-HIP heat treatment considerably reduced the interfacial strength, attributed to dislocation recovery and grain growth. From the mechanical perspective, the work confirmed utilizing HIP capsules during HIP manufacturing provides adequate interfacial strength between 316L SS HIP capsule and SA508 LAS for cladding purposes. The 316L SS HIP capsule may be used as the cladding layer for corrosion protection. [ABSTRACT FROM AUTHOR]

This study investigates the relationship between grain size and material parameters defined in the microscopic hardening laws of the phenomenological crystal plasticity model of Méric–Cailletaud. This investigation is essential for accurate cyclic loading simulations, where the grain size effect on kinematic hardening cannot be neglected. The work was carried out through finite element simulations of the macroscopic plastic behavior of six representative volume elements (RVEs), of austenitic stainless steel 316L, varying in grain size, using a model of Méric–Cailletaud, implemented within the Abaqus software. Experimental literature results serve as benchmarks for adjusting grain size-related hardening parameters. The findings reveal that the studied parameters obey the Hall–Petch law and exhibit an inverse relationship with the square root of the grain size. What is noteworthy is the effect of grain size on kinematic hardening, which differs significantly from previous studies where kinematic hardening parameters were kept constant. Additionally, parameter evolution varies notably between microstructures with coarse and fine grains. Finally, determining hardening parameter variation as a function of grain size provides us with an extended model of Méric–Cailletaud capable of predicting the local as well as the global mechanical behavior of stainless steel 316L in both monotonic and cyclic loading cases, considering the grain size effect. [ABSTRACT FROM AUTHOR]

Interrupted and incremental tensile tests have been carried out on 316 austenitic stainless steel at different strain rates, revealing the correlation between the strain, strain rate, and temperature rise of martensitic transformation. The FERITSCOPE FMP ferrite tester and Telops FAST M2K infrared imager measured the martensite content and surface temperature rise at different strain rates, respectively. The effect of adiabatic temperature rise and strain rate on martensitic transformation was isolated by incremental tests. Compared with the incremental tensile test at a low strain rate (0.001 s−1), it has been found that the increase in strain rate has a negative effect on martensitic transformation, and the effect of strain rate on martensitic transformation seems to be more significant than that of adiabatic temperature rise. The formation and evolution mechanism of strain-induced martensitic transformation of 316 austenitic stainless steel were studied by electron backscattered diffraction. During the process of tensile plastic deformation, the nucleation and growth of new martensite mainly occurred near the twin boundary. [ABSTRACT FROM AUTHOR]

AISI 316L austenitic stainless steel is utilized in various processing industries, due to its abrasion resistance, corrosion resistance, and excellent properties over a wide temperature range. The physical and mechanical properties of a material change during the manufacturing process and plastic deformation, e.g., bending. During the combined tensile and bending loading of a structural component, the stress state changes due to the residual stresses and the loading range. To characterize the component's stress state, the billet was bent to induce residual stress, but a phase transformation to martensite also occurred. The bent billet was subjected to combined tensile–bending and fatigue loading. The experimentally measured the load vs. displacement of the bent billet was compared with the numerical simulations. The results showed that during fatigue loading of the bent billet, both the initial stress state at the critical point and the stress state during the dynamic loading itself must be considered. Analysis was demonstrated only for one single critical point on the surface of the bent billet. The residual stresses due to the phase transformation of austenite to martensite affected the range and ratio of stress. The model for the stress–strain behaviour of the material was established by comparing the experimentally and numerically obtained load vs. displacement curves. Based on the description of the stress–strain behaviour of the pre-deformed material, guidelines have been provided for reducing residual tensile stresses in pre-deformed structural components. [ABSTRACT FROM AUTHOR]

In the context of an increasing interest in the use of high-performance steels in the construction industry due to their superior mechanical properties, understanding the behaviour and assessing the performance of dissimilar welded connections becomes essential. When several steel grades are adopted for fabrication of the same dissipative element, dissimilar welded connections have a decisive importance regarding the seismic performance of the structural member. This paper presents the experimental results of monotonic and low-cycle fatigue (LCF) tests on dissimilar welded connections. The welded connections are designed to reproduce the loading state that occurs between the web and the flanges of dissipative links in an eccentrically braced frame, and represent combinations of S235 mild carbon steel, 1.4404 austenitic stainless steel, and S690 high-strength steel. The obtained experimental results provide a better understanding of the behaviour of dissimilar welded connections through the evaluation of their strength, ductility, and failure mechanisms, providing a basis for finite element (FE) models' calibration for further numerical simulations. This study contributes to the evaluation of the feasibility of connections between dissimilar steels in seismic-resistant steel structures. [ABSTRACT FROM AUTHOR]

Stainless steel is widely used in various industrial fields due to its excellent corrosion resistance and mechanical properties. The key to this corrosion resistance is the thin passive film that naturally forms on the metal surface. Passive films are characterized by oxide film theory and adsorption theory, each uniquely explaining the structure and mechanism of the protective film on the metal surface. Research on the semiconductive properties of passive films on stainless steel offers diverse viewpoints, classifying theories into the point defect model and the bipolar fixed charge-induced passivity. Specific changes in passive film attributes that lead to degradation, however, are not fully understood. In this study, we analyzed the inner and outer layers of the passive film on super austenitic stainless steel SR-50A under various conditions in acidic and alkaline chloride environments. The interpretations of these results were based on the point defect model and the bipolar model for the passivation mechanism, and correlations between p-type and n-type semiconductor properties and passivation behavior were examined. The surface of the stainless steel forms a passive film comprising two layers with p-type and n-type semiconductive properties, independent of the pH of the solutions. The corrosion resistance increases as the p-type and n-type semiconductive tendencies become more balanced, consequently enhancing the properties of the passive film. [ABSTRACT FROM AUTHOR]

AISI 316L austenitic stainless steel superficially modified by the solid nitriding technique was investigated at different nitriding times (2, 4, 6, 8, 12 and 24 h) and at 450 °C. The microstructural characterization was conducted using scanning electron microscopy (SEM) analysis and X-ray diffraction analyses, finding the presence of Fe2–3N, Fe4N and Cr2N, among others. The mechanical behavior of the modified surfaces was carried out by developing hardness profiles and relating it with the nitride layer thickness evaluated using scanning electron microscopy (SEM), obtaining layers up to 70 µm wide. The nitrogen diffusion produced species above and below the surface sample with a transformation from the austenitic phase to an expanded austenite (γN) phase, which is responsible for producing an increase in hardness of up to 1200 HV in the samples treated at 24 h, which is four times higher than the untreated steels. Wear evaluations of the obtained layers were performed using a pin-on-disk system under zero lubrication, indicating that the samples with 12 and 24 h of treatment present the best wear resistance promoted by an oxidative–adhesive mechanism. The obtained results are positively comparable with those of the ion nitriding technique but with a lower implementation cost. [ABSTRACT FROM AUTHOR]

In this paper, a review of the analysis of Fe 2p3/2 peak and other transition metals in the austenitic stainless steel literature is presented. It reveals the significant shortcomings of the most widely used approaches, based on the principle of "chemistry fitting," where single symmetric peaks are used to represent either individual oxidation states or specific compounds. No meaningful conclusions can be drawn from these commonly employed two- or three-component peak fitting (2C and 3C) approaches; the implication being that a large portion of the literature that relies on this approach is flawed. As a significantly more accurate and reliable alternative to "chemistry fitting," we also assess "envelope fitting" (using empirical multiplet structures) and examine its limitations when applying the approach to austenitic stainless steel data. A detailed comparison of these two fitting approaches is described in Part I. For other elements such as Cr 2p, the problems associated with using single components to represent oxidation states or compounds are not as severe. It was found that it does not impact binding energy measurements, but does influence relative intensities, which will have a flow-on effect for oxide thickness calculations and obtaining a correct understanding of the surface more broadly. [ABSTRACT FROM AUTHOR]

A total of 316 austenitic stainless steel (ASS) coatings were deposited on 22MnB5 press-hardening steel plates by varying the substrate bias voltages using a magnetron sputtering technique and quenched in a flat mold with cooling water. The substrate bias current and ion-bombardment energy densities increased up to 0.5 mA/mm2 and 50 J/mm2 at a high voltage of −100 V, and, therefore, the variations in the coatings' morphologies were owing to the increases in the ion bombardment. The porous bulk pattern appeared in the quenched ASS coating at −100 V, clearly different from the porous columnar structure of the others at −50 and −75 V. The γ-Fe and α-Fe phases were observed from the diffraction peaks, presented the ASS coating and 22MnB5 substrate, respectively. There was no intermetallic compound (IMC) peak detected. In addition, the diffusion layer of the quenched ASS-coated plate was observed, in which its morphology was different from the quenched martensite (M) plate, and proved to be the α-Fe microstructure by the very low α-Fe peak at the standard (110) position. The bright image of TEM and the select area electron diffraction pattern indicated the nanostructure of the quenched ASS coating. The nanohardness of the ASS coating, diffusion layer, and M plate (7.36, 3.60, and 6.25 GPa, respectively) was detected, indirectly proving an α-Fe structure of the diffusion layer. The fracture angles of the 316-coated plates significantly improved from 51.82° at −50 V, 53.77° at −75 V to 57.38° at −100 V, as the ASS structure changed to be porous bulk pattern. The clearance of IMC, coating's porous bulk pattern, and the low hardness α-Fe diffusion layer benefited for the fracture strain by lengthening the pathway of the crack's development and blocking the further crack's propagation, respectively. [ABSTRACT FROM AUTHOR]

To detect mechanical overloads on the component directly in operation, a metastable material can be used as a load-sensitive sensor when combined with an eddy current testing system. In order to find a suitable metastable sensor material that exhibits microstructural changes at an early stage before fatigue failure, quasi-static tensile tests and cyclic rotating bending tests were carried out with the austenitic stainless steels 1.4301 (2 batches), 1.4305, 1.4541 and 1.4550. For the detection of microstructural changes, electromagnetic testing was used in-situ in the tensile test and ex-situ between the rotating bending test after a pre-defined number of cycles. The investigated materials 1.4301 batch2 and 1.4550 showed the largest signal changes and the lowest austenite stability both in the tensile test and under cyclic bending load. Due to the better mechanical properties, 1.4301 batch2 should be preferred. The order of the austenitic stainless steels tested was similar in terms of transformation behavior in both tests. Thus, the tensile test combined with in-situ electromagnetic testing appears to have potential as a suitable benchmark test for austenite stability. With regard to the cyclic bending stress, an overload of the specimens could be detected for the materials 1.4301 batch2, 1.4305, 1.4541 and for the 1.4550 on the basis of a significant amplitude change. At low bending stresses, uncritical for structural integrity, no increase in amplitude was measured. The results have shown that an early detection of overloads is possible with several materials, however, the potential for detecting overloads varies between materials and also between individual batches. In addition, it has been observed that as the bending stress increases, the gradient of the change in amplitude over the number of cycles increases as well. Thus, with a known number of cycles, it could be possible to classify the previous load spectrum based on the difference in amplitude between two measurements. [ABSTRACT FROM AUTHOR]

In this study, austenite formation in 201 austenitic stainless steel was observed in two steps during solidification. Initially, austenite (γ1) precipitated and grew on δ-ferrite during the peritectic reaction (δ + liquid → γ1) and formed directly from the residual liquid (γ2). With the addition of Co, from 0.09 to 0.51 wt.%, the dendrite morphology of ferrite changed from columnar dendritic to equiaxed dendritic. Primary ferrite phase morphology changes resulted in an austenite microstructure composed of a uniform dispersion of fine grains. Both ε-martensite (hcp) and α′-martensite (bct) were present in the microstructure due to the deformation of austenite particles by the impact force. The impact toughness increased by 33% as the cobalt content increased to 0.51 wt.%. [ABSTRACT FROM AUTHOR]

The present study reports the effect of laser shock peening (LSP) on stress corrosion cracking (SCC) behavior of the shear cut surfaces of type 304L stainless steel. The LSP is carried out on as shear cut surface of SS 304L steel at a fixed laser power density of 3.53 GW cm−2 with multiple passes, i.e., double and triple. The preliminary investigation showed that as shear cut surfaces of SS 304L possess a very high tensile residual stresses of the order of 450-700 MPa and hardness 400 HK0.1. The LSP treatment with double and triple pass led to the generation of high compressive residual stress of the order of − 200, and − 250 MPa as compared to as cut shear surfaces. Microscopic analysis revealed that the shear cut surfaces, after double and triple LSP treatment exhibited significantly reduced susceptibility to the SCC in chloride environment after 8-hour test. The results of the present study recommend that LSP treatment can acts as protector of the product and components of austenitic stainless steel with sheared cut surfaces stored for long time in susceptible corrosive environment. This way a huge loss to the nuclear and process industries can be minimized. [ABSTRACT FROM AUTHOR]

Surface mechanical grinding treatment (SMGT) is a promising surface strengthening technique by exerting gradient microstructure, phase transformation, and work hardening on the surface layer. However, due to the large strain and high strain rate, it is difficult to evaluate the microstructure attributes of the SMGT-processed surface. In the present work, an analytical model is developed to correlate the SMGT processing parameters to the surface microstructure, grain size, martensite content, and microhardness. Firstly, the processing force and distributions of stress and strain are identified by developing a multi-physics framework for SMGT process. Afterward, the surface grain refinement induced by dynamic recrystallization (DRX) is modeled by cellular automata (CA) method. The grain size along with the depth of cross section is predicted by Johnson–Mehl–Avrami–Kolmogorov (JMAK) DRX model. The martensite content is evaluated according to the strain-induced martensitic transformation kinetics. Ultimately, accounting for both microstructure alteration and phase transformation, the microhardness variation is predicted. To verify the results derived by analytical model, series of confirmatory experiments were carried out on 316L austenitic stainless steel. The SEM was utilized to observe the surface microstructure of the processed samples. The martensitic transformation was characterized by EBSD and XRD methods. The microhardness measurements were taken on an automatic Vickers hardness tester. It was obtained from the results that the surface microstructure, gradient grain size, phase content, and microhardness distribution derived from predictive model were consistent well with the experimental measurements. The confirmed simulation model is further utilized to understand how the process factors, i.e., ball size and penetration depth, influence the evolution of microstructure. It is found that the finer grain structure, higher martensite content, and microhardness can be obtained by adopting smaller ball and larger penetration depth. [ABSTRACT FROM AUTHOR]

Two recently proposed elasto-visco-plastic self-consistent (EVPSC) models, based on solving for stress or stress increment, are discussed, and their results are compared with the ones of the visco-plastic self-consistent (VPSC) approach. The advantages and shortcomings of the models are demonstrated, with emphasis on how the grain responses are affected by the time increment and inclusion-medium interaction strength used. Experimental data obtained for an FCC stainless steel is used as the benchmark system for performing the simulations and assessing the reliability of the results. Predictions of stress-strain response of the aggregate, standard deviations in intergranular stress and strain rate, along with the evolution of internal lattice strain are presented and compared, with special focus on their dependence on the incremental approach chosen. We find that the chosen time increment may significantly affect predicted grain responses. To avoid such effect a method based on using two separate time increments is proposed, one for approximating the stress rate and another for actual integration of stress, strain, and state variables. The proposed method successfully eliminates the dependence of results on the time increment used, thus allowing more reliable computations while preserving the computational efficiency of the elasto-visco-plastic model.

High-nitrogen (high-N) austenitic stainless steels (ASS) are used in orthopedic implants due to their mechanical properties, human biocompatibility, and affordable cost. However, the high content of (Ni–Nb–N)-rich precipitates can cause allergic reactions and significant challenges in the manufacturing of prostheses. This study investigates the competition between work hardening (WH), dynamic recovery (DRV), and dynamic recrystallization (DRX) during the physical simulation of an ASTM F-1586 steel by thermomechanical processing, using the Kocks-Mecking and Avrami constitutive models. The parameters were obtained through continuous isothermal torsion tests at the temperature range of 900–1200 °C, strain rates between 0.01 and 10 s−1 and a total deformation of 4.0. Determined by compositional-analytical methods, the stacking fault energy (γsfe) was correlated with the stress level (σi) according to the Uesugi and Dai models. Results indicated a high activation energy for hot deformation (Qdef = 587 kJ/mol), affecting the shape of the curves. The γsfe value varied along the curves, delaying the onset of the DRX (σc = 0.928σp). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses revealed a direct competition between work-hardened and recrystallized grains in the early part of the curves, due to WH-DRV synergy. After the peak stress (σp), the progress of DRX was slow, with the Avrami exponent (n) between 1.1 and 1.9, completing only after large deformations (σss = 0.714σp). The moderate γsfe value (69 mJ/m2) and fine precipitates of the Z-phase (CrNbN) (

At cryogenic temperatures, 316L austenitic stainless steel (ASS) exhibits remarkable strength while retaining high ductility, defying the conventional stress-strain trade-off. Despite extensive studies documenting the cryo-tensile properties of ASSs, the underlying mechanisms behind this phenomenon remain largely unexplored. This study systematically re-examines the tensile properties of 316L stainless steel and the associated mechanisms across a range of low temperatures (293 K, 223 K, 123 K, and 77 K). The reasons for the superior stress-strain balance (∼80 % GPa) are discussed using results from electron backscatter diffraction (EBSD) microstructure characteristics. The results undoubtedly suggest that the transformation mechanisms, specifically the shift from deformation twinning to martensitic transformation (γ → ε → α′), play a crucial role in enhancing elongation at cryogenic temperatures. At these temperatures, the Gibbs free energy difference between ε-martensite and γ-austenite approaches zero, resulting in slow martensite growth. The stress-strain curves at low temperatures satisfy the Considère criterion, indicating delayed necking under these conditions. This behavior is ascribed to the presence of various hierarchical microstructures, including ε, α′, γ-twins, ε-twins and their intersections, which act as sources of work hardening. This study provides new insights into deformation behavior of ASSs under cryogenic conditions.

Hydrogen embrittlement (HE) resistance is a significant concern in austenitic stainless steel (ASS) used for hydrogen transportation and storage. While microstructure-controlled methods to enhance HE resistance have been extensively studied in ferritic steels, comprehensive research on microstructure effects in ASS is lacking. In this study, two 316L ASSs with different microstructures were evaluated for HE resistance using electrochemical hydrogen charging. The steel with abundant in + orientations showed a significant elongation reduction after hydrogen charging. It revealed that, from the hydrogen permeation and thermal desorption analysis (TDA) results, effective diffusivity and activation energy of hydrogen were changed along the crystallographic orientation distributions. Also, transformation induced plasticity (TRIP) and twinning induced plasticity (TWIP) behavior affecting to the HE resistance preferentially formed in grains with and orientations rather than in those with orientation during plastic deformation. Therefore, the study suggests that reinforcing the microstructure is advantageous for improving HE resistance in 316L ASS.

The weld cladding on the inner surface of nuclear pressure vessels due to irradiation damage and thermal effect presents to a safety issue. Unfortunately, the effect of irradiation and long-term thermal treatment on the austenitic microstructure and austenitic hardening in austenitic stainless steel weld metals (ASSWMs) remains poorly understood. In this study, the effects of irradiation and thermal treatment on the austenitic microstructures and austenitic hardening of 308L ASSWMs were investigated using nanoindentation, atom probe tomography and transmission electron microscopy. The results suggested that irradiation resulted in the formation of Ni/Si-rich clusters, voids, and Frank loops in austenite, thereby inducing austenitic hardening. Subsequently, thermal treatment decreased the size and the number of Frank loops in irradiated austenite, which had a minor effect on austenitic hardening. However, thermal treatment promoted the growth of Ni/Si-rich clusters and void formation, which have a primary effect on austenitic hardening, thereby enhancing the hardening of irradiated austenite. Furthermore, thermal treatment has little effect on the microstructure and hardening of austenite. Then, irradiation promoted the formation of Ni/Si-rich clusters, voids, and Frank loops in thermally treated austenite, resulting in austenitic hardening. The interaction of irradiation and thermal treatment can promote the formation of voids. The austenitic hardening was mainly due to the contribution of Frank loops, voids, and Ni/Si-rich clusters, which acted as short-range barriers by pin-moving dislocations.

The mechanical stress improvement process (MSIP) is a crucial technique employed in nuclear power plants to enhance the reliability and safety of piping systems, which are susceptible to stress corrosion cracking. This study aims to address the significant challenge of preventing such failures by effectively eliminating residual tensile stresses present in weldments. By mitigating these stresses, MSIP helps prevent the formation of new cracks and slows the progression of existing ones in piping systems. This approach induces beneficial compressive stresses along the inner surface of the pipe near the weld, including the molten and heat-affected zones. Multiple cases were analyzed through numerical simulations to assess the efficacy of MSIP in reducing stress concentrations and enhancing structural integrity. Furthermore, the dimensions and placement of the MSIP tool were evaluated, revealing that the optimal position and width of the clamp are 30 mm from the weld line (WL) and 75 mm, respectively. The results indicate that the WL region experiences significantly high compressive stresses, which gradually decrease within a 10-mm distance on each side of the WL. This research contributes valuable insights into the application of MSIP in improving the durability and safety of nuclear piping systems. [ABSTRACT FROM AUTHOR]

The surface morphology has a significant influence on the fatigue behavior of components. For austenitic stainless steels (ASSs), this issue is even more pronounced due to their metastability. Based on the complex deformation mechanisms of metastable ASSs, which include dislocation slip, deformation twinning, and deformation‐induced martensitic phase transformation, the metastable stainless steel AISI 347 was investigated in this study together with the stable AISI 904L as a reference material. Four‐point bending fatigue tests with load ratio R = 0.1 and testing frequency f = 10 Hz at ambient temperature were carried out on specimens with five technically relevant surface morphologies: mechanical polished, milled, microshot peened, laser shock‐peened, and ultrasonic modified. Systematic material characterizations were carried out to elucidate the crucial role of surface roughness and deformation‐induced α′‐martensite in the fatigue behavior of both metastable and stable materials. While surface roughness is a well‐known key factor in conventional fatigue cases, deformation‐induced martensite layers implemented by various surface modification methods were proven to improve the fatigue life in metastable austenitic steels, opening new perspectives to extend the lifetime of ASS components. Highlights: Investigated surface morphology's impact on four‐point bending fatigue in ASSs.Diverse surface treatments to achieve various surface morphologies. [ABSTRACT FROM AUTHOR]

Austenitic stainless steels are used as important structural materials in nuclear reactors due to their high fracture toughness. In the process of long-term service, austenitic stainless steel will be subjected to neutron irradiation to cause microstructural changes, such as the formation of dislocation loop and precipitation, which will lead to a decrease in fracture toughness and affect its service behavior. The irradiation embrittlement behavior of austenitic stainless steels, i.e., the reducing of fracture toughness, should be considered in the life extension of the nuclear reactor. According to the relationship between fracture toughness and tensile properties, the prediction of fracture toughness after irradiation can be realized by using the tensile test data after irradiation. In order to predict the irradiation embrittlement bahavior of austenitic stainless steels, firstly, according to the correlation relationship between irradiation hardening and irradiated microstructure information, the post-irradiation microstructure information was used to predict the tensile yield stress after irradiation. Then, according to the correlation relationship of irradiation hardening and fracture toughness, the uniform elongation, yield stress/flow stress and fracture toughness before irradiation, combined with the yield stress/flow stress and uniform elongation obtained after irradiation, the prediction of fracture toughness of austenitic stainless steel after irradiation was realized, that is, the prediction of irradiation embrittlement of austenitic stainless steel was realized. Through the above steps, the fracture toughness of austenitic stainless steel can be directly predicted based on the microstructure information after irradiation. By using the microstructure information from experimental data obtained in the literature, the predicted fracture toughness was basically consistent with the experimental value of fracture toughness of austenitic stainless steel reported in the literature, which verified the effectiveness of the model. The results show that the dislocation loop formed after irradiation are the main microstructures that cause the irradiation embrittlement of austenitic stainless steels. In the future, the irradiation embrittlement of austenitic stainless steel can be predicted based on the microstructure information obtained by experimental test or simulation calculation, which provides a theoretical guidance for reactor life extension.

This comprehensive review examines the phenomena of stress corrosion cracking (SCC) and chloride-induced stress corrosion cracking (Cl-SCC) in materials commonly used in the oil and gas industry, with a focus on austenitic stainless steels. The study reveals that SCC initiation can occur at temperatures as low as 20 °C, while Cl-SCC propagation rates significantly increase above 60 °C, reaching up to 0.1 mm/day in environments with high chloride concentrations. Experimental methods such as Slow Strain Rate Tests (SSRTs), Small Punch Tests (SPTs), and Constant-Load Tests (CLTs) were employed to quantify the impacts of temperature, chloride concentration, and pH on SCC susceptibility. The results highlight the critical role of these factors in determining the susceptibility of materials to SCC. The review emphasizes the importance of implementing various mitigation strategies to prevent SCC, including the use of corrosion-resistant alloys, protective coatings, cathodic protection, and corrosion inhibitors. Additionally, regular monitoring using advanced sensor technologies capable of detecting early signs of SCC is crucial for preventing the onset of SCC. The study concludes with practical recommendations for enhancing infrastructure resilience through meticulous material selection, comprehensive environmental monitoring, and proactive maintenance strategies, aimed at safeguarding operational integrity and ensuring environmental compliance. The review underscores the significance of considering the interplay between mechanical stresses and corrosive environments in the selection and application of materials in the oil and gas industry. Low pH levels and high temperatures facilitate the rapid progression of SCC, with experimental results indicating that stainless steel forms passive films with more defects under these conditions, reducing corrosion resistance. This interplay highlights the need for a comprehensive understanding of the complex interactions between materials, environments, and mechanical stresses to ensure the long-term integrity of critical infrastructure.

Abstract With the growing interest in utilizing Mg and austenitic stainless steel (ASS) in the automotive sector, joining them together in three-sheet configuration is inevitable. However, achieving this task presents considerable challenges due to the large differences in their physical, metallurgical and mechanical properties. To overcome these challenges, the feasibility of using weld-bonding to join Mg alloy/ASS/ASS was investigated. The nugget formation, interface characteristics, microstructure and mechanical properties of the joints were investigated. The results show that the connection between the Mg alloy and upper ASS was achieved through the combined effect of the cured adhesive and weld-brazing in the weld zone. On the other hand, a metallurgical bond was formed at the ASS/ASS interface. The Mg nugget microstructure exhibited fine columar grains composed predominantly of primary α-Mg grains along with a eutectic mixture of α-Mg and β-Mg17Al12. The nugget formed at the ASS/ASS interface consisted largely of columnar grains of austenite, with some equiaxed dendritic grains formed at the centerline of the joint. The weld-bonded joints exhibited an average peak load and energy absorption of about 8.5 kN and 17 J, respectively (the conventional RSW joints failed with minimal or no load application). The failure mode of the joints changed with increasing welding current from interfacial failure via the Mg nugget/upper ASS interface to partial interfacial failure (part of the Mg nugget was pulled out of the Mg sheet). Both failure modes were accompanied by cohesive failure in the adhesive zone.

The influence of various solution annealing treatments on the microstructure and mechanical properties of a new Cr–Mn austenitic stainless steel with 1.15 wt% (C + N) and 0.51 C/N ratio has been investigated. A sequential solution annealing (SSA) treatment is designed to sufficiently dissolve and lower numerous precipitates including carbides and nitrides in the austenite matrix. In this process, the hot-forged steel is firstly solution heat treated at 1120 °C for 2 h, then continuously heated to 1180 °C for 0.5 h, and further heated to 1200 °C for 0.5 h, followed by water quenching. The experimental results show that the austenite grain size increases, and number of precipitates decreases, with increasing temperature and time of solution annealing treatments. The highest impact energy is obtained after this SSA treatment due to a more homogeneous grain distribution, a smaller amount of carbides remaining on the grain boundary, and solid solution strengthening of interstitial (C + N) atoms.

Aimed at low-cycle fatigue damage of Z2CND18.12N austenitic stainless steel for nuclear power pipelines，the influences of the acquisition and post-processing parameters on the local misorientation （ML） were studied by electron backscattered diffraction （EBSD） technique. The damage evolution of grains with typical orientations was discussed based on the parameters after optimization. The results show that the step size，filter and binning all affect the value of ML. Taking into account factors such as grain size，testing accuracy， and efficiency，the optimal selection is to determine binning 2×2， filter 11×11， and testing step size of 2 μm or 5 μm，respectively. Two damage regions with different levels are characterized. The peak and average values of ΔML in 〈111〉 orientation are higher than those in 〈101〉 and 〈001〉 orientations，and the values of ΔML in 〈101〉 orientation are the smallest. Large ML is observed in small grains，especially in the grain boundaries and intersections. Meanwhile，non-uniformity of deformation distribution was discussed in according to the effects of grain size and grain boundary. It is confirmed that ML can effectively evaluate the deformation damage of Z2CND18.12N steel，which is valuable for the development of material and structural damage evaluation technology based on multi-physical parameters.

The chloride-induced stress corrosion cracking (CISCC) is one of the major integrity concerns in dry storage canisters made of austenitic stainless steels (ASSs). In this study, an advanced duplex stainless steel (DSS) with a composition of Fe–19Cr–4Ni-2.5Mo-4.5Mn (ADCS) was developed and its performance was compared with that of commercial ASS and DSS alloys. The chemical composition of ADCS was determined to obtain greater pitting and CISCC resistance as well as a proper combination of strength and ductility. Then, the thermomechanical processing (TMP) condition was applied, which resulted in higher strength than ASSs (304L SS and 316L SS) and better ductility than DSSs (2101 LDSS and 2205 DSS). The potentiodynamic polarization and electrochemical impedance spectra (EIS) results represented the better pitting corrosion resistance of ADCS compared to 304L SS and 316L SS by forming a better passive layer. The CISCC tests using four-point loaded specimens showed that cracks were initiated at 24 h for 304L SS and 144 h for 316L SS, while crack was not found until 1008 h for ADCS. Overall, the developed alloy, ADCS, showed better combination of CISCC resistance and mechanical properties as dry storage canister materials than commercial alloys.

The pitting corrosion behavior of austenitic stainless steels (SSs) UNS S30400 and UNS S31600 exposed to electroactivated water (EAWA) (oxidation–reduction potential [ORP] 1100 ± 15 mV and pH 4.5 ± 0.2) was evaluated by gravimetric tests, linear and cyclic potentiodynamic polarization (CPP), electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy‐dispersive X‐ray spectroscopy (EDS). Gravimetric and electrochemical results for corrosion rates indicate a good corrosion resistance of the tested SS. However, localized pitting corrosion appears after 1 week of exposure to EAWA, as was corroborated by the results of both corrosion rate and surface analysis. Special care must be taken for the sanitization of SS surfaces used in medical installations to avoid their corrosion when EAWA is applied as a disinfectant. [ABSTRACT FROM AUTHOR]

This work aims to evaluate the behavior of AISI 308L stainless steel, applied in additive manufacturing by direct energy deposition (DED) with the GTA (TIG) process, to find the limits of using this material as a manufacturing technique. The AISI 308L is an austenitic steel with extensive applications across various industrial sectors, particularly in the chemical, food, and biomedical industries. Due to its resistance to ductile–brittle transition, it is widely utilized in cryogenic temperature working conditions. The welding equipment and the test specimen were instrumented for analysis of welding process parameters and evaluation of heat transfer in the material as a function of pulse frequency (0 Hz—conventional GTA, 100 Hz, 1 kHz, and 10 kHz) to determine its influence on ferrite morphology and printability in each test specimen. Under these conditions, the sample was characterized by optical and scanning electron microscopy (SEM) and backscattered electron diffraction (EBSD) to evaluate the direction of solidification by the deposited layer. The results showed that a pulse frequency of 100 Hz reduced the volumetric fraction of ferrite and exhibited the best printability. Furthermore, samples prepared using the pulse frequency showed higher printability values than samples without pulsation, and samples with 10 kHz showed an increase in the formation of acicular ferrite. [ABSTRACT FROM AUTHOR]

A three‐dimensional (3D) microstructural volume is reconstructed from a stack of two‐dimensional sections which was obtained by serial sectioning coupled with electron back scattering diffraction (EBSD) mapping of a 316L austenitic stainless steel. A new alignment algorithm named linear translation by minimising the indicator (LTMI) is proposed to reduce the translational misalignments between adjacent sections by referencing to coherent twin boundaries which are flat and lying on {111} planes. The angular difference between the measured orientation of a flat twin boundary and that of the {111} plane is used as an indicator of the accuracy of the alignment operations. This indicator is minimised through linear translations of the centroids of triangular facets, which constitute grain boundaries at a distance not restricted by the in‐plane step size of the EBSD maps. And hence the systematic trend in the translational misalignments can be effectively reduced. The LTMI alignment procedure proposed herein effectively corrects the misalignments remained by other methods on a 3D‐EBSD data prepared using serial sectioning methods. The accuracy in distinguishing between coherent and incoherent twin boundaries is significantly improved. [ABSTRACT FROM AUTHOR]

The microstructure of stainless steels belonging to the martensitic and martensitic–ferritic classes was examined by orientation microscopy (EBSD) after quenching. The steels comprised 15 wt % Cr, Ni, and Nb, and were distinguished by the addition of Cu or Mo as alloying elements. Using the spectra of deviation of interfacial α/γ-boundaries from orientation relationships (OR), as well as the initial austenitic grain recovery procedure according to OR, it was found that the martensitic transformation occurring in both steels is realized according to the closest to Kurdyumov–Sachs OR, or (112)γ || (113)α; [11 ]γ || [1 0]α OR. It is demonstrated that the δ-ferrite grains present in the martensitic−ferritic grade steel prior to and after quenching are in the same OR with austenite. This appears to be a consequence of the nucleation of martensitic crystals at the δ-ferrite/austenite phase interface. It is demonstrated also that the application of orientation microscopy enables the ascertainment of the grain austenitic structure of stainless steels at elevated temperatures with an acceptable degree of precision. This is realized by analyzing the structure resulting from shear transformation. [ABSTRACT FROM AUTHOR]

The wear and corrosion resistance of 316L austenitic stainless steel after strain hardening were studied. 316L austenitic stainless steel was composed of a large amount of austenite and a small fraction of martensite. After strain hardening at room temperature, the contents of phases were not changed basically. With the increase of pre-strain deformation, the microhardness of the surface and cross-section slightly increased, and the microhardness of the sample with pre-strain deformation of 20% was the largest. When the pre-strain deformation was greater than 5%, the surface microhardness was greater than the cross-sectional microhardness. The dynamic average friction coefficients of the stainless steel after pre-strain deformation of 0%, 5%, 10%, and 20% were 0.67, 0.57, 0.2, and 0.12, respectively. The friction coefficient of the samples gradually decreased with the increase of strain hardening. The wear resistance of 316L stainless steel was improved after pre-strain deformation. The steel with pre-strain deformation of 20% had a small abrasive scratch depth and low friction coefficient, which exhibited good wear resistance. The corrosion resistance of the samples after strain hardening deteriorated for the initial state without immersion due to the existence of defects. The corrosion resistance of the sample with pre-strain deformation of 5% after soaking for 3 days was the best, compared with the other as-strained samples. [ABSTRACT FROM AUTHOR]

Controversy surrounds the potential of grain refinement in suppressing metal hydrogen embrittlement (HE). The literature presents two methods for introducing hydrogen into metals: hydrogen pre-charging (HPC) and hydrogen in-situ charging (HISC). This study compares the effect of grain refinement on HE under electrochemical HPC and HISC conditions, focusing on type 304 austenitic stainless steel with a grain size range of 0.5–35 μm. HE behaviors were evaluated through tensile testing and fracture morphology analyses, while hydrogen diffusion and concentration were examined using hydrogen uptake amount measurements and hydrogen permeation tests, complemented by finite element (FE) simulations. Results indicate that coupling with plastic deformation significantly accelerated hydrogen transport in the HISC condition, leading to higher apparent hydrogen diffusivity compared to the HPC condition, with grain boundaries (GBs) act as hydrogen traps. Under the HISC, grain refinement reduced HE susceptibility by decreasing the apparent diffusivity due to an increased trapping effect of GBs and suppressing intergranular fracture by reducing the hydrogen amount distributed to each GB (hydrogen occupancy of the GBs). However, grain refinement to below 1 μm increased HE under the HPC condition. Hydrogen permeation tests showed that under the HPC, grain refinement slightly decreased hydrogen diffusivity. In the ultrafine-grained specimen, as GBs trapped more hydrogen atoms, they not only provided hydrogen to stress-concentrated lattices and newly-formed dislocations by detrapping but also maintained a higher hydrogen occupancy of the GBs, thus increasing HE. It is concluded that whether grain refinement suppresses HE depends primarily on the resulting hydrogen occupancy of the GBs, which is influenced by the charging conditions rather than the quantity of traps. • A comparison of effect of grain size on HE in 304 steel is conducted under in-situ H charging and pre-charging. • Coupling with plastic deformation accelerates H transport in in-situ charging condition. • Grain refinement reduces HE in in-situ charging, but it slightly decreases and then increases HE in pre-charging. • The former is attributed to decreased H diffusivity and reduced H occupancy of grain boundaries (GBs). • The latter is due to that H-filled GBs act as H reservoirs, providing H to stress concentrations and dislocations. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive set of characterization techniques are employed to demonstrate that the cold spray deposition process can result in a significant increase in martensite in austenitic stainless steel. The lack of consensus in the literature on the formation of strain-induced martensite in cold spray can be attributed to the diverse processing conditions and measurement techniques used in different studies. In this work, EBSD, neutron diffraction, TEM imaging, and precession electron diffraction were used in combination to examine whether strain-induced martensite is formed during cold spray deposition of 304L stainless steel powder and to give further insight into possible mechanisms controlling this phenomenon. Cold spray was performed at both 350 °C and room temperature (25 °C) to investigate the effects of spray temperature on the martensite transformation. It is shown that the strain-induced martensite formation is significantly suppressed compared to that which would be expected for comparable levels of plastic strain at quasi-static strain rates. Additionally, the spray gas temperature is shown to directly impact the microstructure formed at the prior particle interface and the formation of dynamically recrystallized regions. [ABSTRACT FROM AUTHOR]

The root cause failure investigation for a ruptured secondary superheater (SSH) tube in a heavy oil-fired boiler was undertaken. The technical investigation disclosed severe microstructural degradation in terms of intermetallic phase precipitation, creep cavities and carburization of tube's external surface. The dimensional survey revealed significant thickness reduction along periphery of fractured surface. A semi-quantitative analysis of surface deposits was performed by scanning electron microscopy and x-ray diffraction to characterize and identify the sources of corrosive deposits. The detection of low melting eutectic vandates in external deposits induced the possibility of fireside corrosion. A comparative analysis was drawn between competing mechanisms of fireside corrosion and long-term overheating to reckon the root cause of the failure. Furthermore, a microstructural evolution model for fine-grained austenitic stainless steel (SA-213 TP347 HFG) suffering simultaneously from fireside corrosion and long-term overheating was developed. The investigation was concluded with notable recommendations and protective measures against fireside corrosion for superheater tubes for boiler life extension and maintaining overall equipment reliability. [ABSTRACT FROM AUTHOR]

This paper investigates the leak failure of an austenitic stainless steel condenser tube observed during the hydrostatic test operation using visual inspection, scale analysis, and the micrographic analysis by scanning electron microscope equipped with energy-dispersive X-ray spectroscopy (SEM/EDS). The results showed that the inner surface of the failed condenser tube experienced the localized pitting corrosion, initiated from the inner, and continued through the thickness of the tube. Rod-like and leaf stalk-like microorganisms and the biofilm were found in the scale layer covering the affected area. Tunneling corrosion attack was also clearly found. EDS spectra results indicated the significant sulfur content in corrosion pits. All of the findings indicate that microbiological-influenced corrosion assisted by sulfate reduction bacteria was response for the leakage failure of the condenser tube. [ABSTRACT FROM AUTHOR]

The study investigates the impact of mechanical cleaning, citric acid+sodium hydroxide (CA), and nitric acid (NA) passivation on welded SS304 stainless steel plates, taking into consideration surface roughness. An innovative EIS paste–based cell is employed for this purpose. Welded systems in both the heat-affected (HAZ) zone and base metal (BM) are being analyzed before and after each treatment. Specifically, one welded plate underwent mechanical cleaning, another was solely subjected to CA passivation, and a third received both mechanical cleaning and CA passivation. Aging tests were conducted in a condensation chamber to confirm the effectiveness of cleaning and passivation treatments. Regarding open-circuit potential (OCP), most samples remained within the passive region, except for the mechanically cleaned heat-affected zone and the intentionally abraded surface immediately after abrasion. Rp values, which are in line with the OCP measurements, range from 104 to 107 Ω cm2 for all the observed samples. As the degree of abrasion on the NA-passivated surface increases, the electrochemical impedance spectroscopy (EIS) spectrum shifts from that characteristic of the passive towards that characteristic of the active state of the stainless steel. [ABSTRACT FROM AUTHOR]

This study investigated the role of interfacial deformability in bond integrity and strength, particularly in the production of robust joints between harder austenitic stainless steels (SS) during ultrasonic welding. The specimen without the interlayer experienced limited strength enhancement owing to internal cracking from continuous sliding at interfacial temperatures below 0.6 times the melting point (Tm), which is attributed to the limited deformability of the austenitic SS. In contrast, introducing Fe and Ni interlayers between the substrates resulted in a notable increase in the interfacial strength, surpassing 2500 N in the peak load within a reduced welding duration. The correlation between the interfacial strength and the peak temperature suggests that a substantial decrease in hardness below 0.4 Tm is sufficient for extensive bond formation. Moreover, dynamic recrystallization (DRX) led to grain refinement in the Fe interlayer owing to shorter weld durations, whereas grain growth was observed in the Ni interlayer due to higher peak temperatures. Both the Fe and Ni interlayers significantly improved the bonding integrity by accommodating plasticity through the above phenomena without severe damage to the substrates, leading to increase of interfacial strength by 24% (2050 N to 2500 N) and reduction of weld duration by 40% (1.5 s in Fe interlayer). In addition, the fracture position after the lap shear test shifted from the edge of the weld area to the SS substrate. [ABSTRACT FROM AUTHOR]

304 austenitic stainless-steel (SS) strip-based carbon fiber metal laminates (CFMLs) have raised significant concerns, in terms of their mechanical performance. On top of that, the hybrid laminates' interlamination performance is vital in regulating their failure patterns. Along these lines, in this work, SS strips with regulatable micromorphology and composition were obtained by using physical and chemical surface modification strategies, including polishing, acid etching, anodization, and thermal treatment. The shear strength of the treated-SS/epoxy single lap joints (two treated-SS strips bonded by the epoxy resin via hot curing process) was systematically explored, and the origins of the enhancement mechanism were attributed to the resulting surface microstructure, as well as the possible chemical reactions between the treated surface and the curing agent. The etching-anodizing-thermally treated-SS (EAT-SS)/epoxy joint exhibited the maximum shear strength (16.04 MPa) and work of fracture (5.85 kJ·m−2) due to the substantial cohesive failure pattern of the epoxy. The encouraging enhancement was mainly attributed to the synergistic effect of the micro-annular pit and the nanoporous array structure of the EAT-SS surface. These effects induced a significant mechanical interlock and a plausible chemical reaction at the interface, which led to improved bonding strength between the epoxy and treated-SS surface. Overall, in this work, it was demonstrated that the combination of the anodization and thermal treatment can effectively improve the interlamination bonding properties between the SS strip and the epoxy resin due to the combination effect of mechanical interlocking and chemical bonding. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Dissimilar welds between ferritic and austenitic stainless steels are widely used in industrial applications. Taking into account the issues inherent to arc welding, such as the high heat input and the need to carry out multiple passes in the case of thick plates, a procedure with two simultaneous laser beams (working in a single pass) and consumable inserts as filler metal has been considered. Particular attention was paid to the choice of the filler metal (composition and amount), as well as welding parameters, which are crucial to obtain the right dilution necessary for a correct chemical composition in the weld zone. The first experimental investigations confirmed the achievement of a good weldability of the dissimilar pair ASTM A387 ferritic/AISI 304L austenitic steel, having ascertained that the microstructure of the weld zone is austenitic with a little amount of residual primary ferrite, which is the best condition to minimize the risk of hot cracking. [ABSTRACT FROM AUTHOR]

Austenitic stainless steel (ASS) and duplex stainless steel (DSS) are referred as "difficult-to-cut" materials in the manufacturing industry because of different machining difficulties including work hardening, high cutting temperatures and formation of built-up layers. DSS is the preferred replacement for ASS but includes a difficult manufacturing environment. Moreover, the wet machining conditions raise several issues related to the human health, environment, disposition and costing. However, turning of these materials in the dry environment is a challenging task. The present research work is a comparison of machinability aspects of ASS 304 and DSS 2205 in a dry environment using AlTiN coating deposited by two advanced coating deposition techniques including direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS). Uncoated tools showed the worst performance at every stage of machining. AlTiN (HiPIMS)-coated tools showed the lowest increase in average surface roughness of 8%, 17% lower cutting force and 1.5-times higher tool life compared to AlTiN (DCMS) tools. DSS 2205 was the most difficult material to machine in dry conditions, exhibiting the lowest average tool life of 3890 mm compared to 4315 mm by ASS 304. Moreover, HiPIMS-coated tools helped in improving the machining performance of DSS 2205 up to some extent. [ABSTRACT FROM AUTHOR]

The autogenous manual gas tungsten arc welding (GTAW) process was used for cladding austenitic stainless steel 316L using a single pass with various contact tip-to-work distances (CTWDs). Immersion and electrochemical tests were used to evaluate the corrosion resistance of the welded specimens, and a microstructural analysis was conducted to investigate the chemical composition of the molten pool and the heat-affected zone of welding. The key findings of this study indicate that the corrosion resistance improved under a CTWD of 5 mm due to the optimal distribution of ferrite and a refined microstructure. Additionally, the highest hardness was observed in specimens with a CTWD of 3 mm, attributed to the increased ferrite content in the weld metal. As the CTWD increased, the ferrite fraction decreased, and the hardness also diminished. However, in the CTWD 7 mm case, the higher heat input influenced the microstructure and molten pool shape significantly through the Marangoni effect, resulting in a lower corrosion resistance. These results suggest that optimizing the CTWD can enhance the corrosion resistance of welded 316L stainless steel. [ABSTRACT FROM AUTHOR]