Stainless Steel Sections Research Articles

Influence of a nanoscale coating on plucking fingers and stainless steel on attachment and detachment of Salmonella Enteritidis, Escherichia coli and Campylobacter jejuni

Gastroenteritis caused by Campylobacter represents the most common reported foodborne bacterial illness worldwide, followed by salmonellosis. Both diseases are often caused by the consumption of contaminated, insufficiently heated poultry meat. This can result from contamination of the meat during the slaughtering processes. Food contact surfaces like stainless steel or plucking fingers contribute significantly to cross-contamination of poultry carcasses. Modification of these surfaces could lead to a reduction of the bacterial burden, as already proven by successful application in various food industry sectors, such as packaging.In this study, nanoscale silica-coated and uncoated stainless-steel surfaces and plucking fingers were compared on a pilot scale regarding attachment and detachment of Campylobacter jejuni, Salmonella Enteritidis and Escherichia coli.The bacteria did not adhere less to the coated plucking fingers or stainless-steel sections than to the uncoated ones. The coating also did not lead to a significant difference in detachment of Campylobacter jejuni, Salmonella Enteritidis and Escherichia coli from the investigated surfaces compared to the uncoated ones.Our study did not reveal any differences between the coated and uncoated surfaces with regard to the investigated bacteria. In order to achieve a better adaptation of the coating to slaughterhouse conditions, future studies should focus on its further development based on the investigation of specific coating parameters.

The effect of weld bead heat input on the performance of thick 3CR12 stainless steel welds

3CR12 is a low cost special stainless steel containing 12% chromium. It is widely used in material handling, road transport, rail transport, power generation and petrochemical applications due to its favorable corrosion performance. 3CR12 is a weldable material, but it has challenges such as poor ductility, poor toughness of 3CR12 stainless steel welds, unfavorable microstructure and cross-sectional properties of the weld bead. This is due to the welding heat input and heat transfer across beads, which causes cracking due to property changes. When welding a thick stainless steel section, the hardest heat affected zone (HAZ) is created due to uneven heating and cooling in the weld metal and base material, which is susceptible to cold cracks and residual stresses, resulting in welding defects and unfavorable material properties. Welding thick 3CR12 stainless steels can be accomplished by using a variety of welding techniques. In order to restore undesirable material qualities, the majority of welds require a post-weld heat treatment (PWHT). However, critical PWHT factors such as duration, weld geometry, and unsupported loads during the hot phase of the weld do not always allow the process to be effective. This process results in prolonged downtime since the holding time in the PWHT cycle can be very long, especially with thick-walled 3CR12 steel members. There are other methods that are currently used to weld or repair thick 3CR12 steels. Among these other methods, the use of controlled temper bead welding technique which potentially could mitigate the above mentioned problems is mentioned. The approach involves using the heat input of the weld bead as a way of introducing the heat into the previous weld bead. This is achieved by varying the heat input in order to improve the mechanical performance of the previous weld bead and thus the overall weld integrity. Welding procedures for 3CR12 recommend the use of minimum heat to avoid weld defects and unfavorable material properties. This study was carried out to investigate the effect of the heat input of the weld bead on the mechanical properties of thick welds made of 3CR12 stainless steel. By utilizing inert gas (MIG) welding, two heat input levels were used in the process: low heat input averaged at 1.53 kJ/mm and high heat input averaged at 2.1kJ/mm. The heat input was varied by changing the welding parameters, for example the average welding voltage ranging from 28V to 30V, the average welding current from 120 A to 150 A and the average feed rate between 1.77mm/sec to 2.0mm/sec.

Strengthening Stainless Steel Tubular Beams using Fibre-reinforced Concrete incorporating Sugarcane Bagasse Ash

Stainless steel tubular beam sections have been increasingly utilised for structural applications due to the enhanced properties of stainless steel over conventional mild steel. However, thin-walled stainless steel sections are not effectively used for several practical applications due to the higher costs and its response to easily undergo local buckling under flexural loading. Consequently, to overcome these effects, concrete infilling is a generally preferred strengthening mechanism that enhances the overall capacity and makes the sections economic. Earlier research studies on the flexural behaviour of various concrete-infilled stainless steel composite beam specimens are highly limited. Therefore, this study mainly focuses on the flexural behaviour of bare stainless steel tubular beams, sugarcane bagasse ash blended concrete-infilled stainless steel composite beam, and fibre-reinforced sugarcane bagasse ash blended concrete-infilled stainless steel composite beam. The study uses sugarcane bagasse ash as a pozzolan in the infill concrete to produce durable and sustainable concrete. In the same manner, crimped steel fibres are incorporated to enhance the ductility of the beam specimen. The parameters such as ultimate strength, maximum flexural deformation, initial stiffness, failure modes, ductility, and moment-rotation profiles were comprehensively investigated for all the beam specimens. Furthermore, numerical modelling was performed for the fibre-reinforced sugarcane bagasse ash blended concrete-infilled stainless steel composite beam specimen and was validated with the experimental results. It was witnessed that adding infill concrete to the stainless steel tube enhanced the beam specimens' load-carrying capacity, stiffness and ductility.

Structural performance of stainless steel sections fabricated by laser-welding, hot-rolling and extrusion

This paper presents an experimental investigation on the structural performance of austenitic stainless steel columns with open sections fabricated by laser-welding, hot-rolling and extrusion. The aim of the experimental programme was to quantify and compare the effect that different fabrication techniques have on the structural behaviour of the columns. The investigated cross-sections were extruded and laser-welded I-sections with the American designation S5x10, and hot-rolled and laser-welded channel sections with the European designation UAP 120x60x6. All sections were fabricated from austenitic stainless steel grade 1.4307/1.4301 (dual certified). The experimental programme consisted of stub and long column tests, as well as measurements of all the parameters that were considered to have an impact on the structural behaviour of the sections, including: material properties, cross-sectional geometry, residual stresses and global geometric imperfections. The tests showed that although the residual stresses and geometric imperfections of the austenitic stainless steel laser-welded columns are similar to those of the extruded/hot-rolled columns, their structural performance was noticeably better than that of the extruded sections, and equivalent to that of the hot-rolled sections. The experimental data was also used to assess the adequacy of the European column curves for laser-welded and hot-rolled open sections susceptible to flexural buckling about the minor axis. It was found that while for laser-welded I-sections it may be possible to justify a higher buckling curve, more research is needed for channels.

Web crippling resistances of cold-formed stainless steel sections: A proposal for EN 1993-1-4

The current EN 1993-1-4 does not have supplementary web crippling design provision for cold-formed stainless steel sections under local transverse forces. Therefore, designers are generally referring to the guidance in EN 1993-1-3 for cold-formed carbon steel sections. Over the past decades, quite a substantial number of tests have been carried out worldwide to study the behaviour of cold-formed stainless steel sections undergoing web crippling, among which the majority of the data were focused on C-sections as well as square and rectangular hollow sections (SHS and RHS). To this end, tailor-made design provisions for these stainless steel sections can be developed. In this study, up-to-date web crippling test data on cold-formed stainless steel C-sections and SHS/RHS were firstly collected. The applicability of the web crippling design provisions as per the new version of EN 1993-1-3 to stainless steel sections was assessed. New design provisions for cold-formed stainless steel unstiffened C-sections (unlipped channels), stiffened C-sections (lipped channels) as well as SHS and RHS under local transverse forces are proposed in this study. The newly developed web crippling design provisions for C-sections and SHS/RHS were derived based upon reliability requirements as regulated in EN 1990 using available experimental data reported on austenitic, ferritic and duplex stainless steel types of various grades. The proposed design provisions for stainless steel sections have been made in line with the development of the new version of EN 1993-1-3 provisions and therefore are recommended to EN 1993-1-4 for calculating web crippling resistances under local transverse forces.

Experimental investigation on the square and rectangular hollow section stainless steel portal frames

Cold-rolled hollow sections are the most commonly used stainless steel sections in the construction industry, because the production of this type of profile is the most cost-effective in smaller volumes. However, very little experimental research has been carried out so far on whole structures made of these sections. Therefore, experiments on stainless steel frames were carried out. In total, 5 portal frames made of austenitic stainless steel SHS/RHS were tested. These tests are described in detail, including the layout of auxiliary elements and measuring devices. The aim of the experiments was to capture the effects of material nonlinearity on the global behaviour of the stainless steel frames. The load–displacement diagrams are presented in tables, enabling their use for the validation of numerical models. Tensile coupon tests were carried out and parameters for common material models were determined. Numerical models of the studied frames were developed and validated using the experiments performed. These numerical simulations have been shown to be able to capture the general load–displacement response in a global, in-plane mode. Linear buckling analysis was carried out. Resulting elastic critical load factors indicated a high susceptibility of the frames to second order effects. In addition, modified elastic critical load factors were determined, showing the large influence of material nonlinearity on second order effects.

Element diffusion and microstructure evolution at interface of stainless steel/Ti alloy joint by laser welding with AgCuTi filler metal

Joining of 304 stainless steel and TC4 titanium alloy was of great interest for applications in the marine, and aerospace fields. However, the direct welding process of steel and titanium will generate a large number of brittle Ti–Fe intermetallic compounds results in crack in joint. In this study, in order to avoid the formation of Ti–Fe intermetallic compounds, the connection between stainless steel and titanium alloy is successfully realized by adding AgCuTi filler metal. A section of unmelted stainless steel was retained by laser offset welding, and the filler was diffusion bonding with the base metals on both sides by heat conduction, ensuring that the filler was not melted. Since Fe and Cu elements have high solid solubility in liquid state, so the stainless steel and filler interface formed a good connection. There was no Ti–Fe intermetallic compounds found in the joint, and Ti2Cu and AgTi2 intermetallic compounds with better ductility was formed at the filler-TC4 interface. In order to further explore the element diffusion distribution at the interface of the joint. The temperature distribution model in the fusion zone was established, and obtained the temperature field of the joint. The diffusion coefficients of Fe, Cu and Ti elements were calculated by Arrehenius formula. It was verified that the diffusion of Ti elements in the filler resulted in the aggregation of Ti elements at the filler-TC4 interface. The microstructure mechanism for formation of the brazed weld was proposed.

Cold Roll Forming Process Design for Complex Stainless-Steel Section Based on COPRA and Orthogonal Experiment.

Cold roll forming can fabricate products with complex profiles, and its parameter optimization can achieve high quality and improved precision of products. In this paper, taking the side shield as a typical product, the cold roll forming of a complex section of stainless steel SUS301L-ST is analyzed, establishing a 3D finite element model by using the professional roll forming software COPRA. We propose a floating roll device for complex sections with asymmetry and large depth. We use an orthogonal experiment to obtain the inter-distance between rolls, friction coefficients, the diameter increments, and line velocities to investigate the effects on the maximum longitudinal strain of the edge. Results show that the diameter increment has the greatest influence on the maximum strain, and its increases can reduce the strain. The inter-distance value needs a suitable range. A small value is not conducive to the release of elastic deformation, while a large value will cause unexpected displacement and increase the cost. The friction coefficient increases; although it helps to reduce the strain, it will cause scratches and other defects on the stainless steel. The increase in velocity increases the strain. We derive the optimal parameters for the complex section, providing a theoretical basis for practical production.

Web Crippling Behaviour of Cold-Formed Carbon Steel, Stainless Steel, and Aluminium Lipped Channel Sections with Web Openings

This paper reviews the research advancements and design practices related to the structural web crippling response of lipped Cold-Formed (CF) carbon steel, stainless steel, and aluminium channels with web perforations. The web crippling response differs among each material based on the non-linear stress-strain characteristics and degree of strain hardening. Therefore, the reduction in the web crippling strength of web-perforated CF channel sections made of different materials may not be equivalent. The research activities surrounding the web crippling response of CF channels with and without web openings were reviewed initially. Despite the limited design provisions given in the international specifications for the web crippling design of lipped CF channels with web openings, web crippling studies conducted across the world have developed suitable design equations in the form of reduction factors. Past research studies have substantially captured the web crippling response of carbon steel channels with web openings while that of stainless steel and aluminium are limited, as identified in this paper. Lastly, numerical models were developed for simulating the web crippling behaviour of lipped CF carbon steel, stainless steel, and aluminium channels with web opening and validated with past experimental data, with a view for developing unified design guidelines.

Cross-sectional behaviour of wire arc additively manufactured tubular beams

Wire arc additive manufacturing (WAAM) is a promising metal 3D printing technique in the construction industry for its ability to produce large and complex-shaped elements, with reasonable printing accuracy, time and costs. There is currently, however, a lack of fundamental test data on the structural performance of WAAM elements. To address this, an experimental study into the cross-sectional behaviour of WAAM tubular beams has been conducted and is presented herein. A total of 14 stainless steel square, rectangular and irregular hollow sections, spanning over all cross-section classes of EN 1993-1-4 and AISC 370, were tested in four-point bending. 3D laser scanning, silicone casting and Archimedes’ measurements were employed to collectively determine the as-built geometry and local geometric imperfections of the test specimens, while digital image correlation (DIC) was used to monitor the deformation responses of the specimens during testing. The full moment–curvature histories and key experimental results are presented and discussed. Similar cross-sectional behaviour to that of equivalent, conventionally manufactured sections was observed, with the more slender cross-sections showing increased susceptibility to local buckling. However, owing to the inherent geometric variability of WAAM, the tested 3D printed beams exhibited more variable flexural capacities between the repeat specimens than is generally displayed by conventionally produced stainless steel sections. Finally, the test results were used to assess the applicability of current cross-section design provisions in the European (EN 1993-1-4) and American (AISC 370) structural design specifications, as well as the continuous strength method (CSM), to WAAM stainless steel tubular beams.

Flexural performance of steel fiber reinforced concrete filled stainless steel tubular trusses

The stainless steel tubular truss is known for dealing with corrosion problem of tubular truss, and mechanical properties of tubular truss can be improved ulteriorly by filling concrete to effectively avoid local buckling of steel tubular. To study the influence of the filling position of steel fiber reinforced concrete (SFRC) on flexural behavior of stainless steel tubular truss, four-point bending tests were carried out on four specimens. The specimens consist of three SFRC-filled stainless steel tubular trusses and a hollow section stainless steel tubular truss as control group. The experimental results show that filling the chord with SFRC can significantly improve the bearing capacity of the stainless steel tubular truss. At the same time, the internal mechanism of SFRC improving the bearing capacity of the structure is analyzed from the perspectives of failure mode, overall deformation characteristics and strain development of material. The effects of several different SFRC filling methods on improving the mechanical performance of specimens were compared. Finally, the finite element method is used to analyze the tested specimens. The accuracy of the proposed finite element modeling is proved, and the optimal filling method to make full use of the material property of SFRC is obtained through stress analysis.

Fire design of stainless steel I beams prone to lateral torsional buckling under end moments

It is known that the loading type significantly influences the resistance of steel I-beams to lateral torsional buckling (LTB), which led to the development of Eurocode 3 design rules accounting for the beneficial effect of non-uniform bending in laterally unrestrained beams. New calculation formulae for stainless steel beams under fire conditions have recently been proposed for incorporation in the second generation of Eurocode 3 − their safety evaluation in the context of different bending moment diagrams is still a relevant issue that needs to be investigated. This paper presents a numerical study on the resistance of stainless steel I-beams with slender and non-slender cross-sections and undergoing LTB when acted by end moments at elevated temperatures, focusing on the influence of the moment gradient. The safety and accuracy of the Eurocode 3 design approaches (current and second generation versions), as well as a design proposal previously developed for beams with stocky stainless steel sections, are assessed through the comparison of their predictions with extensive numerical failure moments obtained with the software ANSYS. It is shown that the design proposal previously developed for stainless steel beams with stocky sections provides the best predictions, even if having considerable number of underestimations.

Characterization and Aerodynamics of Synthesized Polymeric Nanofibers via Electrospinning Process to Capture PM10 and PM2.5 from Air

Air quality is an important factor for human breathing requirements. The presence of the particulate matter which is a mixture of solid particles and liquid droplets presence in atmosphere such as PM10 and PM2.5 in the indoor air leads to fatal problems for human health. In the present investigation, two types of nanofilters (polyacrylonitrile PAN, 15wt.% and polyvinyl alcohol PVA 12wt.%) were synthesized using the electrospinning method. The polymeric solutions were prepared under high mixing conditions. The structural and morphological specifications of produced nanofibers were characterized using many measuring devices. Also, airflow characteristics across the prepared nanofilter were evaluated by designing and constructing an airflow apparatus. The apparatus consisted of two stainless steel sections and the middle zone was designed to fit the filter media. The characterization results indicated that the synthesized of PVA 12 wt.% nanofilter has uniform morphological distribution with fibers average diameter of 92 nm while the produced PAN with 15wt.% showed and an average fibers diameter of 556 nm. Moreover, the PVA nanofilter showed high-pressure values in comparison with the PAN filter. Interestingly, both filters provided high air permeability. Furthermore, the produced PAN nanofilter showed a high ability to capture the PM10 and PM2.5 due to the significant properties and specifications of nanofibers. Additionally, the produced nanofilter can be applied in air filtration processes effectively with low manufacturing costs.

Numerical study on fire resistance of rectangular section stainless steel-concrete composite beam

To investigate the fire resistance of stainless steel-concrete composite beams (referred to as stainless steel composite beam), numerical simulations of rectangular section stainless steel composite beams under fire were carried out. The influences of load ratio, thickness of concrete slab, width of concrete slab, reinforcement ratio of concrete slab, height of stainless steel beam, width of stainless steel beam and span of composite beam on the fire resistance of rectangular section stainless steel composite beams were analyzed. Due to the large coefficient of thermal expansion of stainless steel material, the expansion of stainless steel beam will produce an additional bending moment in the stainless steel composite beam under fire, which has a great influence on the fire resistance of stainless steel composite beams. Finally, a simplified calculation method of temperature field distribution of rectangular section stainless steel composite beam was proposed. To adjust and enlarge the maximum bending moment at the mid-span of stainless steel composite beam, the coefficient of temperature additional bending moment was introduced into the calculation formula of critical temperature of stainless steel composite beams, which effectively improves the accuracy of the fire-resistant design method for stainless steel composite beams.

Parametric study of stainless steel slender I‐section beams

AbstractThe contribution shows a numerical parametric study and experimental research of welded slender stainless steel I‐section beams. Difference in behavior of stainless steel and common carbon steel members is generally known, but design of stainless steel members has been established mainly for hollow sections (CHS, SHS/RHS) as these are the typical stainless steel profiles. Currently, open stainless steel sections are also being used in structures and the design rules for both local buckling of very slender sections as well as lateral torsional buckling reduction factors are based on very limited experimental and numerical research. For this reason new research covering these phenomena was carried out at the Czech Technical University in Prague. A numerical model was used for design of test arrangement, the geometrically and materially nonlinear analysis with imperfection was made in software Abaqus. The experimental program consisted of six stainless steel beam tests being used for a model validation. The tests employed two stainless steel materials (austenitic and ferritic steel), one section slenderness (Class 4 for web and flange) and three beam slenderness. A parametric study based on the validated numerical model was carried out with the main focus on lateral‐torsional buckling of slender Class 3 and Class 4 welded I‐sections. A comparison to the existing design procedures is shown. In limited amount, resistance of Class 4 stainless steel sections in bending was also investigated.

Compact and slender box concrete-filled stainless steel tubes under compression, bending, and combined loading

An extensive investigation on the behaviour of compact and slender box concrete-filled stainless steel tubular (CFSST) members is carried out studying their response under compression, bending, and combined compression and bending, with the main aim of developing comprehensive design procedures. Under this objective, an experimental programme is first conducted comprising compact and slender CFSSTs fabricated from austenitic and lean duplex stainless steel plates. Stub columns under axial compression as well as combined compression and bending, CFSST beams under pure bending, and long CFSST columns under axial force are all included in the experiments in order to investigate both the section and member responses. Specimens with high width-to-thickness ratios, high length-to-width ratios, and those under combined compression and bending are particularly considered in the experiments as test data is very scarce for such CFSSTs in the literature. A special technique is used to estimate the loads carried individually by the stainless steel section and the concrete infill to assist with the development of design recommendations. The experiments are followed by an extensive numerical study comprising over two hundred three-dimensional nonlinear finite element simulations. Outcomes of the experimental and numerical programmes are presented, analysed, and discussed thoroughly. Comprehensive procedures are then developed for the design of compact and slender CFSSTs under compression, bending, and combined loading which incorporate the effects of local and global buckling in strength predictions. Such procedures have not yet been established for CFSSTs in international design standards. The validity of the recommendations is demonstrated through comparison with the results of the present study as well as the test data available in the literature.

Behaviour and design of stainless steel-concrete composite beam-to-column joints

Stainless steel is considered a promising construction material for steel and composite structures owing to a number of superior features concerning excellent durability, high ductility and aesthetic benefits. Over the past few decades, a great deal of research has investigated the behaviour and design of stainless steel structural members. However, there is still very limited knowledge on the behaviour of joints between stainless steel/composite beams and columns. This paper presents for the first time, an experimental study on the structural behaviour of stainless steel-concrete composite (SSCC) beam-to-column joints, highlighting the “all stainless steel” concept (including stainless steel sections, bolts, reinforcing bars and shear connectors) to ensure a consistent service life within the entire structural system. Two types of stainless steels are incorporated in this study, namely austenitic and lean duplex. In addition to the experiments, 3D finite element models are established and validated against the test results in order to perform further parametric study. Based on the experiments and numerical analyses, the key structural characteristics of SSCC joints are evaluated and compared with the design predictions by Eurocode 3/4 and AS/NZS 2327. It is concluded that the existing design method (initially developed for carbon steel composite joints) cannot be directly applied for SSCC joints considering the unique material characteristics of stainless steel, i.e. the nonlinear stress-strain behaviour and immediate strain-hardening after yielding. Modifications to the existing method is therefore proposed for design of SSCC joints.

Shear behaviour of cold-formed stainless-steel beams with web openings: Numerical studies

Cold-formed stainless-steel (CFSS) sections are increasingly popular for architectural and structural applications, especially in the corrosive environment due to its resistance to corrosion and other various benefits. The combination of stainless-steel material properties and the lightweight section properties makes the CFSS section the right choice for offshore steel structures. The demand for the stainless-steel sections in the construction industry is limited to a certain extent due to the higher cost; thus, the optimal use of stainless steel is vital. Openings to the web of CFSS Lipped Channel Beams (LCB) are introduced to facilitate the building services to reduce the floor height. Subsequently, the shear capacity is reduced due to the reduction of the web area. However, only very limited researches have been conducted so far to predict the reduced shear capacity of CFSS LCBs with circular web opening. Hence, this paper addresses a numerical study to investigate the shear behaviour and strength of cold-formed austenitic grade 1.4301 and duplex grade 1.4462 stainless steel LCB sections with unreinforced circular web openings. A detailed parametric study was carried out by developing 180 Finite Element Analyses (FEA) models to establish a wide-ranging shear strength database following the validation process with available shear test results. The analysis of the numerical results showed that the currently available reduction factor equations are either conservative or unsafe to use for the CFSS LCBs with circular openings. Hence, three sets of equations with different approaches to predict the shear capacity of CFSS LCBs with circular web opening are developed and presented in this paper.

Design of stainless steel cross-sections with outstand elements under stress gradients

A significant amount of research has been reported on stainless steel tubular sections, while studies on I- and C-sections remain relatively limited. This paper presents a comprehensive numerical study on the response of stainless steel I- and C-sections subjected to minor axis bending, with outstand flanges subjected to stress gradients. Numerical models are developed and validated against reported test data on austenitic stainless steel sections under minor axis bending. Subsequently, parametric studies using standardised material properties on austenitic, duplex and ferritic stainless steel grades, covering a wide variety of cross-section slendernesses, are carried out to expand the structural performance data. The results are used to assess the applicability of the Eurocode slenderness limits, revealing that the Class limit 3 for outstand flanges under stress gradient is overly conservative. Moreover, Eurocode underestimates the predicted bending strengths, whereas the level of accuracy and consistency improves for stocky sections, when the Continuous Strength Method is used. Aiming to address the lack of accuracy and consistency in the design predictions of slender sections, particular focus is placed on their performance. It is demonstrated that outstand elements under stress gradients exhibit significant inelastic behaviour after the compression flanges have locally buckled. Inelastic buckling behaviour is not considered in current design guidance, thus resulting in overly conservative and fundamentally incorrect strength predictions. An alternative design method based on the plastic effective width concept is proposed for slender stainless steel I- and C-sections in minor axis bending, which leads to more favourable and less scattered strength predictions.

Buckling Behaviour of Hollow Stainless Steel Sections

Buckling Behaviour of Hollow Stainless Steel Sections