Stainless Steel Bolts Research Articles

Tensile Properties of Aluminum Alloy Bolt-Sphere Joints under Elevated Temperatures

Aluminum alloy bolt-sphere joint is one of the major nodes in aluminum alloy space grid structures. It has been applied in many big projects. In this study, computation methods of mechanical properties and bearing capacity of aluminum alloy bolt-sphere joints in fire are proposed by combining experimental research and theoretical analysis. Results demonstrate that: 1) The tensile strength of aluminum alloy bolt-sphere joints in fire is related to the tensile strength of stainless-steel bolt and the tensile strength seal plate joint. 2) The stainless-steel bolt develops two failure modes, namely, breakage failure of cord and pulling-out failure of screw in fire. 3) The seal plate joint in fire has three tensile failure modes, namely, tensile-shearing combined failure of seal plate at the annular compression position, shear failure of seal plate, and tensile failure of the aluminum alloy tube at the seal plate border. 4) The tensile strength of the stainless-steel bolt begins to decrease significantly when the temperature reaches 300°C. 5) The tensile strength of the seal plate joint begins to decrease sharply when the temperature reaches 200°C. 6) The formula to calculate bearing capacity of aluminum alloy bolt-sphere joints in fire is proposed based on experimental results.

Experimental behaviour and fracture prediction of austenitic stainless steel bolts under combined tension and shear

This paper describes an experimental programme and numerical studies on the behaviour of austenitic stainless steel bolts under combined tensile and shear loading. Extensive experimental tests under tension, shear and combined loading were conducted for A4–70 and A4–80 austenitic stainless steel bolts, as well as grade 8.8 carbon steel bolts for comparison purposes. From the test results, the austenitic stainless steel bolts showed unique behaviour such as much higher ductility and specific failure mode compared with conventional carbon steel bolts. The predictions of existing design provisions (especially the AISC codes) for stainless steel bolts under combined loading were found to be unsafe in some circumstances. Moreover, in order to establish a complete framework for fracture prediction of stainless steel bolts, finite element models were developed, incorporating a fracture model calibrated by the bolt test results. To illustrate the performance and applications of the developed method, numerical examples of stainless steel bolted connections were carried out. It was found that the proposed method could reasonably predict the fracture behaviour of stainless steel bolts under tension and shear.

Fatigue behaviour of stainless steel bolts in tension and shear under constant-amplitude loading

This paper experimentally investigates the fatigue performance of stainless steel bolts in tension and shear under constant-amplitude loading. The static behaviour of normal bolts and Hollo-bolts subjected to monotonic loading was initially reported aiming to obtain the ultimate strength. Periodic loading tests were thereafter performed to acquire tensile and shear fatigue life under various stress ranges in which failure modes and cycles were recorded. From test results, S-N curves were summarised through regression analysis, followed by numerical modelling which was used to investigate the stress distribution. Finally, different design codes were selected to estimate the fatigue limit of bolts in tension and shear. It was found that both coupon tests and monotonic loading tests are required to determine the material property of stainless steel bolts. Regions adjacent to bolt nuts are the most vulnerable parts in terms of fatigue in tension, and the maximum principal stress dominates the fatigue life of fasteners with threads in shear plane. The fatigue strength of Hollo-bolts is slightly higher than that of normal bolts. Moreover, although current design codes can conservatively estimate the fatigue behaviour, provisions for shear fatigue are recommended to be modified for higher accuracy and better application.

Evaluation of strength of stainless steel bolt without heat treatment considering Bauschinger effect during manufacturing process

Abstract Isotropic hardening models for elastic-plastic materials are often used to simulate cold forging processes, although it cannot represent the Bauschinger effect. However, the Bauschinger effect must be considered for precise simulation of the strength in service of cold-forged components without heat treatment, as well as their geometry. A cold-forged bolt made of stainless steel is a typical example. In this report, finite element analysis of the forming process and the strength was performed for two multi-stage cold forging processes of non-heat-treated stainless steel bolts. The Yoshida-Uemori model was used as a kinematic hardening model that takes into consideration the Bauschinger effect of a material. The Yoshida-Uemori model was modified so that they can represent the strain hardening behavior in a large strain region appropriately for applying the model to cold forging process. As a result, it was possible to account for the Bauschinger effect during the forming process. Moreover, it was possible to estimate the difference in strength between the isotropic and kinematic hardening models by analysis of the tensile test results. Furthermore, the impact of the forming process on the strength of the cold-forged bolt was also evaluated.

Galling is a serious issue in many industries that use stainless steel fasteners- but there are solutions

Galling is a form of wear that is caused bymetal surfaces in gliding contact with one other, such as the sometimes hundreds of stainless-steel bolts and fasteners holding production equipment and its moving parts together. With potentially disastrous effects resulting from galled fasteners seizing or even being subject to a fatigue breakage, industry players are advised to counter this threat.

Study of stainless steel bolted extended end-plate joints under seismic loading

Bolted stiffened extended end-plate (BSEP) joint is a commonly used beam-to-column joint in steel frames. In this paper, five full-scale stainless steel BSEP joints were tested under cyclic loading. The tested joints were made of Grade S31608 (EN 1.4401) stainless steel welded I-sections, assembled by four types of bolts, including galvanized high strength bolts of Grades 10.9 and 8.8, and austenitic stainless steel bolts of Grade A4-70 and A4-80. Variations of end-plates of different thicknesses (16 mm and 20 mm) were also considered in the design of the test specimens. Material properties of the plates were tested and the slip-resistant behaviour of the bolts with surface treatments were obtained prior to the joint tests. The test setup, loading protocol and instrumentation employed in the tests are described herein. The obtained test results are reported, including the full moment-rotation curves and the failure modes of the joints. It is observed from the seismic tests that hysteresis curves of all specimens show some sliding and pinching, especially for connections with stainless steel bolts or thin end-plates. The test results were used to validate finite element (FE) models, which can be employed for further numerical investigations. The test results were also employed to assess the stiffness and moment resistance capacity predictions according to the current European design provisions.

EXPERIMENTAL RESEARCH AND FEM ANALYSIS ON BEHAVIOR OF BEAM-COLUMN CONNECTIONS MADE OF STAINLESS-STEEL

In order to study further the resistance and rotation capacity of beam-column connections made of stain-steel S31608, this paper presents the experimental results of connection details under monotonic loading. stainless-steel bolts A4-80 and bearing connection instead of friction type connection are adopted for beam-column connections to improve connection form. An efficient and accuracy FEM model is proposed for numerical simulation under monotonic loading based on the material stress-strain relationship of stain-steel structure and bole A4-80. The connection strength and stress concentration at the end of the weld access hole and the root and the longitudinal direction of the wing plate of a connection are analyzed and compared between the connections. The comparison between FEA results and experimental data shows that the maximum bearing capacity is 251.6 kN and 246.3 kN, and that the maximum displacement is 197.9mm and 196.1mm respectively. Thusly, the nonlinear FEA method is satisfactory in simulating the behavior of bolt connections under monotonic loading and utilizable for later parameter analysis appropriately.

Flexural behavior of double- and single-layer aluminum alloy gusset-type joints

A gusset-type joint (GJ), which comes in single and double layers, is a common joint form in aluminum alloy reticulated shells. Existing studies on the mechanical properties of aluminum alloy GJs (AAGJ) focused mainly on single-layer AAGJs, whereas the mechanical properties of double-layer AAGJs remain unexplored. In this research, the flexural behavior of single- and double-layer AAGJs in the Caofeidian Coal Bunker was experimentally studied through eight full-scale joint tests. The failure mode, rigidity, internal stress distribution, stress transmission mode, and ultimate bearing capacity of the tested joints were determined. Contrast analyses were performed between the in-plane and out-of-plane flexural behaviors of a single-layer joint, as well as between the flexural behaviors of GJs with Huck and stainless steel bolts and between those of single-layer and double-layer GJs. Results if this study provide references for the design of GJs, especially double-layer ones.

Introducing a mechanically robust SPME sampler for the on-site sampling and extraction of a wide range of untargeted pollutants in environmental waters

The present study introduces a mechanically robust, sealable SPME sampler for the on-site sampling and extraction of a wide range of untargeted pollutants in environmental waters. Spray-coating and dip coating methodologies were used to coat the surfaces of six stainless steel bolts with a layer of HLB/PAN particles, which served as the extractive substrate in the proposed device. In addition, this sampler was designed to withstand rough handling, long storage times, and various environmental conditions. In order to identify whether the sampler was able to stabilize extracted compounds for long periods of time, the effects of storage time and temperature were evaluated. The results of these tests showed no significant differences in the quantity and quality of the extracted chemicals following 12 days storage at room temperature, thus confirming the device's suitability for use at sampling sites that are far away from the laboratory facilities. The proposed device was also used to perform extraction and untargeted analyses of river waters in five different geographical locations. The constituent chemicals in the samplers were analyzed and determined using high-resolution HPLC-Orbitrap MS. Toxin and Toxin-Target Database was used as a reference database for toxins and environmental contaminants. Ultimately, over 80 tentative chemicals with widely varying hydrophobicities ranging within −2.43 < logP <11.9—including drugs, metabolites, wide ranges of toxins, pesticide, and insecticides—were identified in the samplers used in the different rivers. The log P values for the tentative analytes confirmed that the introduced device is suitable for the extraction and trace analysis of wide ranges of targeted and untargeted pollutants.

Static and fatigue behavior of pultruded FRP multi-bolted joints with basalt FRP and hybrid steel-FRP bolts

This study investigates the effect of bolt types on the static and fatigue performance of basalt fiber-reinforced polymer (BFRP) multi-bolted double-lap connections. Three types of bolts are used: stainless-steel (SS), BFRP, and hybrid steel-FRP (HSFRP) bolts. Firstly, static tensile tests using steel single-bolted double-lap connections are conducted to determine the mechanical properties and failure modes of the proposed bolts. Secondly, static and fatigue tests using BFRP double-lap connections with six bolts of either SS, BFRP, or HSFRP were conducted. Finally, post-fatigue static tests were conducted to evaluate the deterioration of the composite joints caused by fatigue loading. Load-displacement curves, failure modes, fatigue life, S-N curves, and stiffness degradation are used to evaluate the effect of the bolt type on the behavior of the BFRP joints. Results indicated that SS bolts can be replaced entirely with BFRP bolts without affecting the static and fatigue performance of the joints. In addition, compared to the brittle failure of both the SS and BFRP bolts, the proposed HSFRP bolts exhibited ductile behavior which could be the key to achieving ductile composite structures. Moreover, the HSFRP bolts dramatically prolonged the fatigue life of the composite joints compared to the joints with SS and BFRP bolts.

Feasibility study of a hybrid FRP-steel cable-stayed pedestrian swing bridge

The paper illustrates the feasibility study of a cable-stayed, pedestrian, swing bridge crossing the Navicelli Canal in Pisa, Italy. The static scheme of the bridge is asymmetric with one tower and three pairs of stays. The maximum span length is 21.26 m and the useful width is 2.50 m. According to the proposed design, the bridge deck will be made of glass fibre-reinforced polymer pultruded profiles; the tower and stays will be of ordinary steel; stainless steel bolts and plates will be used for the connections. A finite element model of the bridge was developed to analyse its structural behaviour during construction, service life, and maintenance operations. Construction stages – with particular attention to the cable stringing procedure – were carefully studied to help reduce the overall deformability of the bridge. Structural verifications were carried out according to the EuroComp Design Code, Italian CNR instructions, and German DIBt specifications. The calculated total weight of the bridge deck is about 11 t, including non-structural elements. Thanks to the low self-weight of the deck, a 3 kW electric motor will be sufficient for movement, with savings in both installation and operational costs with respect to a full steel bridge.

Behaviour of stainless steel bolts after exposure to elevated temperatures

This paper presents experimental results of residual material properties of stainless steel bolts (austenitic grades A2–70 and A4–70) after exposure to elevated temperatures. Effects of temperature (20–900°C) and cooling method (cooling in air and cooling in water) on the mechanical properties (i.e., Young's modulus, yield stress, ultimate strength, ultimate strain and strain hardening exponent) of the two types of bolts are investigated. The residual properties of the stainless steel bolts are also compared with those of structural austenitic stainless steel and conventional high-strength structural bolts made of carbon steel. It was found that the exposure to elevated temperature only had a marginal influence on the residual behaviour of stainless steel bolts, which is consistent with the observation for structural austenitic stainless steel. In general, stainless steel bolts have superior post-fire performance compared with conventional carbon steel bolts. Based on the test data, an existing model proposed earlier for structural austenitic stainless steel was modified to predict stress-strain curves of stainless steel bolts after exposure to elevated temperatures.

Electrodeposition of Co-Ni-Fe on Stainless Steel Bolts

In a fastening system, bolt is the first component to be susceptible to corrosive attack. The focus of the study is to investigate the feasibility of coating stainless steel 304 bolts and the coating properties obtained. In this study, the bolts were coated with cobalt-nickel-iron (Co-Ni-Fe) alloy through electrodeposition using platinized titanium as the anodes. The temperature used was 50°C and the pH of the sulphate solution were 2. The current density was 96.68 mA/cm2 and deposition time was 30 minutes. The optimum electrodeposition parameters were studied through trial and error. The characteristics of coating such as elemental percentage and microhardness were compared with the substrate. The optimum parameters obtained were current density of 145.01 mA/cm2, temperature of 60°C and 30 minutes of deposition time. The suitable substrate orientation was horizontally hanged and rotated 60° around screw axis for every 5 minutes. The mean thickness of coating was 117.4 µm. The coating exhibited 25% hardness improvement over the substrate. The 2 litres solution could be used for 7.5 hours (15 plating cycles) to produce 15 samples. As a conclusion the surface hardness was not compromised despite that Co-Ni-Fe ions had depleted in the solution.

Hemilaterally masked arterial spin labeling by intentional magnetic field changes in the labeling area due to placement of material with high susceptibility.

Background and purposeArterial spin labeling(ASL)with magnetic resonance imaging (MRI) is an effective method for estimating cerebral blood flow (CBF). Furthermore, assessing perfusion territories of arteries is useful for determining the treatment strategy of patients with carotid artery stenosis. ASL with selective vessel labeling is an effective method to obtain perfusion mapping, however, the application for selective labeling is not installed on all MR scanners. The purpose of this study is to establish a method to selectively mask in the labeling area using material with high susceptibility instead of selectively labeling to obtain a partial perfusion image.Materials and methodsASL perfusion images were performed in five volunteers. Masking was applied by placing a stainless-steel bolt and nuts on the neck. The area of artifacts extended to the carotid artery was confirmed by the localizer image. In the obtained masked ASL, blood flow of the left and right cerebrum and cerebellum was measured and compared with control ASL without masking. By subtracting masked ASL from the control ASL, the perfusion territory of the carotid artery on the masked side was identified.ResultsMean CBF which was 39.6 ml/(100 g × min) in control ASL decreased to 16.1 ml/(100 g × min) in masked ASL, and the masking ratio was 59.6%. There were no significant differences in the CBF of non-masked areas under the control ASL condition (39.6± 5.2 ml/[100 g × min]) btween that under the masked ASL condition (39.4 ± 7.0 ml/[100 g × min]). By subtracting masked ASL from control ASL, we successfully visualized the hemilateral carotid artery’s perfusion territory.ConclusionIntentional susceptibility artifacts with non-magnetic metals on the neck can mask spin labeling of the carotid artery. Furthermore, hemilateral carotid artery perfusion territories can be visualized in hemilaterally masked ASL.

Design, Fabrication, Construction, and Cost Assessment of Virginia’s First Corrosion Resistant ASTM A1010 Plate Girder Bridge

This study documents the construction of the Waynesboro Route 340 Bridge with low-maintenance corrosion resistant steel girders, cross-frames, and stainless steel bolts. This includes documenting the fabrication of the ASTM A1010 steel plate, girder and secondary members, erecting the girders, and completion of the construction process. The types of stainless steel materials used to fabricate the girders are reported with a comparison to traditional materials. Information on the material properties was documented. Cost analysis was performed and guidance was provided to the Virginia Department of Transportation (VDOT) about how this type of plate girder will benefit the DOT. Overall, the design, fabrication, and construction of the A1010 steel girder Route 340 bridge was a success. This is the first bridge in the United States to use A1010 haunched girders, completely stainless steel bolted splices, and A1010 cross frames. To that end, it was concluded that a conventional steel bridge fabricator can successfully fabricate an A1010 steel bridge. Through detailed testing of the stainless steel bolts, it was also shown that acceptable utilization of stainless steel structural connections can be achieved. VDOT was also able to successfully demonstrate fabrication of A1010 steel cross frames utilizing bent plate shapes. It is recommended to continue to evaluate improved welding processes for the A1010 base metal and to consider the use of A1010 as a repair material for in-service structures located in corrosive macro-environments, such as near saltwater or industrial sites, or those which contain aggressive micro-environments such as steel beam ends under joints.

Reduction factors for stainless steel bolts at elevated temperatures

This paper presents an experimental investigation of the mechanical properties of sixty A4-70 and A4-80 stainless steel bolts under steady-state temperatures ranging from 20 to 900 °C. The material responses at elevated temperatures of the parent materials, SUS316 and SUS316Ti stainless steels (also known as EN 1.4401 and EN 1.4571 steels), and of fire-resistant bolts are included for comparisons. The tensile strength degradation of stainless steel bolts in fire are found to be reasonably close to those specified by Eurocode 3 Part 1.2 for their parent materials, but the Young's modulus degradation is not so robust. At temperatures lower than 650 °C, the stainless steel bolts retain their 0.2% proof strength better than their parent materials. Importantly, in the temperature range of 500 to 900 °C the stainless steel bolts retain their tensile strength, Young's modulus and 0.2% proof strength better than fire-resistant bolts (BOLTEN110N-FR to JSSII-09 standard). Based on the experimental data, reduction factors for tensile strength, Young's modulus and 0.2% proof strength are derived in this paper for stainless steel bolts at elevated temperatures.

Experimental behaviour of stainless steel bolted T-stub connections under monotonic loading

A comprehensive experimental study on structural behaviour of stainless steel bolted T-stub connections is presented in this paper. A total of 27 stainless steel bolted T-stubs with various geometric configurations were fabricated from hot-rolled stainless steel plates and assembled with stainless steel bolts. Two stainless steel grades − austenitic EN 1.4301 and duplex EN 1.4462, and two other types of stainless steel bolts − A4-70 and A4-80, were introduced in the experimental programme. Tensile coupon tests were performed to determine the material properties of the stainless steel plates and bolts. The bolted T-stub specimens were tested under monotonic loading, and ultimate resistances, plastic deformation capacities and failure modes were obtained. Based on the experimental results, the existing design methods for predicting tension resistances of the bolted T-stub connections, including design provisions in EN 1993-1-8, the continuous strength method (CSM), AISC manual and JGJ 82 and other design formulae for T-stubs with four bolts per row, were all evaluated. It was indicated that all the existing design methods provided generally conservative predictions for stainless steel bolted T-stub connections.

Austenitic Stainless Steel Bolt Failure by Stress Corrosion Cracking

AbstractDuring a minor inspection of a heavy-duty gas turbine engine, the hexagonal head of a bolt used for fixing a metal plate in the air intake was found on the floor of the air intake casing [1, 2]. The respective washer was not found. It is believed to have been ingested into the engine, having caused moderate compressor damage. The inspection was started after 83.500 operating hours. Only one fractured bolt was found. The subject bolt fractured due to stress corrosion cracking (SCC), induced by pitting corrosion and possibly assisted by crevice corrosion.

Discussion of “Robustness of Beam-to-Column End-Plate Moment Connections with Stainless Steel Bolts Subjected to High Rates of Loading” by G. Culache, M. P. Byfield, N. S. Ferguson, and A. Tyas

Discussion of “Robustness of Beam-to-Column End-Plate Moment Connections with Stainless Steel Bolts Subjected to High Rates of Loading” by G. Culache, M. P. Byfield, N. S. Ferguson, and A. Tyas

Shaping the Hexahedral Head of a 12Kh18N10T Stainless Steel Bolt

The manufacture of 12Kh18N10T austenitic stainless steel bolts with a hexahedral head is analyzed. The mechanical properties of 12Kh18N10T steel are tested after tempering and calibration to the initial dimensions. Two production technologies are considered: cold stamping with trimming of the hexahedral head; and cold flash-free stamping of a hexahedron. The quality of the head is better in the latter case. The best depth of the depression in the hexagonal bolt head made by flash-free stamping is determined.