scholarly journals Approaches to the Mechanical Properties of Threaded Studs Welded to RHS Columns

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1429
Author(s):  
Ismael García ◽  
Miguel A. Serrano ◽  
Carlos López-Colina ◽  
Fernando L. Gayarre ◽  
Jesús M. Suárez

The use of Rectangular Hollow Sections (RHS) as columns in steel construction includes important advantages like higher mechanical strength and fire resistance. However, the practical demountable bolted joints between beams and columns are not easy to execute, due to impossibility of access to the inner part of the tube. The use of threaded studs welded to the face of the tube and bolted to the beam by means of angle cleats is one of the cheaper and most efficient solutions to obtain beam–column joints with a semi-rigid behavior, as is usually sought in building structures. Nevertheless, it is important to point out that the stud-diameter and the stud-class selection may affect the mechanical properties of the welded parts of the joint. In this paper, 8MnSi7 (with a commercial designation K800) and 4.8 threaded studs were welded to RHS steel tubes and mechanical properties on the weld, the Heat Affected Zones (HAZ), and the base metal were obtained in two different ways: through a correlation with the Vickers hardness and by means of the Small Punch Test (SPT). A study of the microstructure and tensile tests on the threaded studs and in the columns was also carried out. The research involved different types of stud qualities, tube wall thicknesses, and stud diameters. The work presented in this paper proved that in most cases, the welded joint between these studs and the RHS steel tubes present a reasonable static behavior that fulfils the requirements for the beam–column joints under static loading.

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3805 ◽  
Author(s):  
Janusz Kluczyński ◽  
Lucjan Śnieżek ◽  
Krzysztof Grzelak ◽  
Artur Oziębło ◽  
Krzysztof Perkowski ◽  
...  

In this study, we analyzed the mechanical properties of selectively laser melted (SLM) steel obtained via different modifications during and after the manufacturing process. The aim was to determine the effects of precipitation heat treatment on the mechanical properties of elements additively manufactured using three different process parameters. Some samples were additionally obtained using hot isostatic pressing (HIP), while some were treated using two different types of heat treatment and a combination of those two processes. From each manufactured sample, a part of the material was taken for structural analysis including residual stress analysis and microstructural investigations. In the second part of the research, the mechanical properties were studied to define the scleronomic hardness of the samples. Finally, tensile tests were conducted using a digital image correlation (DIC) test and fracture analysis. The treated samples were found to be significantly elongated, thus indicating the advantages of using precipitation heat treatment. Additionally, precipitation heat treatment was found to increase the porosity of samples, which was the opposite compared to HIP-treated samples.


2017 ◽  
Vol 891 ◽  
pp. 330-334 ◽  
Author(s):  
Šárka Stejskalová ◽  
Ladislav Kander ◽  
Šárka Hermanová

The paper deals with the change of the structure and mechanical properties of the austenitic steels after the exposure at the critical temperature. The effects of the bend radius of tubes including effect of solution annealing on the mechanical properties and the structure were studied. The mechanical properties were studied using small punch test (SPT) and miniaturized tensile tests. From the results can be concluded that the mechanical properties and the structure have been influenced due to one year exposure at the working temperature significantly. Various amounts of σ-phase were found in the pulled part of the bend side of the tubes even after only thermal exposure without any loading. The effect of the heat treatment and the bend radius on the mechanical properties and the structure was also evident. Drop in fracture energy due to the presence of the σ-phase in the structure was clearly detected from force - displacement record of the small punch test. Keywords: Austenitic steels, bends, σ-phase, small punch test


Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5224
Author(s):  
Anna Wójcicka ◽  
Krzysztof Mroczka ◽  
Jerzy Morgiel

The elaboration of a modified friction-extrusion method aimed at obtaining 2017A aluminum rods of gradient microstructure is described. This was achieved by cutting spiral grooves on the face of the stamp used for alloy extrusion. The experiments were carried out at a constant material feed (~10 mm/min) and a range of tool rotation speeds (80 to 315 rpm). The microstructure observations were carried out using light microscopy (LM) and both scanning and transmission electron microscopy (SEM and TEM). The mechanical properties were assessed through hardness measurements and static tensile tests. The performed investigations show that material simultaneous radial and longitudinal flow, enforced by friction of the rotating tool head and extrusion, results in the formation of two zones of very different microstructures. At the perpendicular section, the outer zone stands out from the core due to circumferential elongation of strings of particles, while in the inner zone the particles are arranged in a more uniform way. Simultaneously, the grain size of the outer zone is refined by two to four times as compared with the inner one. The transfer from the outer zone to the core area is of gradient type. The hardness of the outer zone was found to be ~10% to ~20% higher than that of the core.


BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 3214-3223
Author(s):  
Ricardo Acosta ◽  
Jorge A. Montoya ◽  
Johannes Welling

The tension test parallel-to-fiber in anisotropic materials, such as bamboo, is one of the most important tests because it makes it possible to evaluate mechanical properties used in calculations for different types of stresses. For this type of test there are standards that apply to wood in general, others to bamboo, and other more specific ones that apply to bamboo Guadua angustifolia Kunth. These rules suggest the use of dog bone test specimens. When performing such tests parallel to the fiber direction, failures are observed in undesired zones. This document characterizes and analyzes the possible types of failures. It also evidences the difficulties presented and quantifies them finding that, for 59 failed test pieces, only 18.6% had failures within the desired zones, while the other 81.4% had failures within undesired zones in the tension test parallel to the fiber. Finally, it can be concluded that there are gaps in the rules that influence the variation of the results obtained by different authors. The dog bone test specimens are not recommended for tension tests parallel to the Guadua fiber. Rather, utilization of straight specimens is recommended with a calculated clamping height and the standard equation and protected clamping area.


2020 ◽  
Vol 56 (2) ◽  
pp. 209-220
Author(s):  
J. Górka

The article presents the analysis of the structure and properties of joints made of abrasion-resistant plates having the structure of chromium cast iron and welded with filler metals, the use of which aimed to provide the high abrasion resistance of the surface layer and good mechanical properties of the base material. The face layer of the joint was made using the MMA (Manual Metal Arc) welding method and the Fe-Cr-Nb-B type nanocrystalline filler metal. The root weld was welded using an austenitic filler metal, whereas the filling layer was welded using the MAG method with a low-alloy filler metal. The joints were subjected to non-destructive tests (visual tests and penetrant tests) as well as to mechanical properties tests. The research involved macro and microscopic metallographic tests, the determination of the grain size using an Xpert PRO X-ray diffractometer, and the EDS analysis of the chemical composition of the precipitates. The assessment of the operational properties of the joints based on hardness measurements, static tensile tests, bend tests as well as identifying the metal-mineral abrasive wear resistance were performed in accordance with ASTM G65 ? 04 standards. The results of the abrasion resistance tests were referred to the HARDOX 400 steel reference specimen. Considering the tests results it was concluded that the used filler materials can assure the appropriate operational properties of welded abrasion-resistant plates.


2013 ◽  
Vol 592-593 ◽  
pp. 279-282 ◽  
Author(s):  
Stefan Soltysiak ◽  
Martin Abendroth ◽  
Meinhard Kuna ◽  
Steffen Dudczig

Carbon bonded alumina (Al2O3-C) in various compositions are developed for the production of open cell filters, which are used for melt metal filtration processes [. The Small Punch Test (SPT) is used to determine the mechanical properties of such materials. Previous investigations showed two different types of fracture behavior [2,, which can be distinguished by typical features of the load deflection curves of the SPT. This paper clarifies this behavior by examining the fracture surfaces using scanning electron microscopy (SEM).


2018 ◽  
Vol 10 (0) ◽  
pp. 1-8 ◽  
Author(s):  
Olena Shkundalova ◽  
Arvydas Rimkus ◽  
Viktor Gribniak

Additive manufacturing and modern printing technologies using polymeric materials extend the limits of industrial production and encourage applying 3D printing technique in many fields. An item of any shape and size limited only by the printing pad of particular equipment can be reproduced from a variety of materials. Polymers is the object of this research. It is known that mechanical properties of the printed elements are closely related with the manufacturing technology and vary significantly depending on the chosen production parameters such as printing temperature, velocity, and infill density. Depending on the purpose, a particular type of polymer can be used in structural analysis. This work considers mechanical properties of four thermoplastic polymeric materials widely used for prototyping: polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS), and polyethylene terephthalate (PETG). The study is focused on two fundamental mechanical characteristics, tensile strength and modulus of elasticity, of the printed material. Dumbbell-shaped samples were made of the PLA, ABS, HIPS and PETG polymers using 3D printing technique with the same filling density (≈ 20%) of the entry level. The tensile tests were carried out in Laboratory of Innovative Building Structures at Vilnius Gediminas Technical University. The predominant effect of the printing direction on the mechanical properties of the printed materials was demonstrated in this study. The corresponding experimental characteristics are presented in the manuscript. Santrauka Modernūs gamybos procesai ir spausdinimo technologijos, naudojant polimerines medžiagas, plečia pramoninės gamybos ribas bei skatina taikyti 3D spausdinimo technologijas daugelyje sričių. Tokios technologijos leidžia gaminti bet kokios formos elementus iš įvairių medžiagų, o jų dydį lemia tik naudojamos spausdinimo įrangos galimybės. Pagrindinis šio tyrimo objektas – polimerinės medžiagos. Spausdintų elementų iš polimerinių medžiagų mechaninės savybės glaudžiai siejamos su gamybos technologija ir gali stipriai varijuoti keičiant gamybos proceso parametrus – spausdinimo temperatūrą, greitį, užpildo tankį. Polimero tipas kartu su jo mechaninėmis savybėmis parenkamas atsižvelgiant į konstrukcinį uždavinį. Šiame darbe nagrinėjamos plačiai prototipų gamyboje taikomų termoplastinių polimerinių medžiagų – polietileno rūgšties (PLA), akrilonitrilo butadieno stireno (ABS), polistireno (HIPS) ir polietileno tereftalato (PETG) – mechaninės savybės. Tyrime dėmesys skiriamas dviem pagrindinėms mechaninėms medžiagų charakteristikoms – tempiamajam stipriui ir tamprumo moduliui. Taikant 3D spausdinimo technologiją buvo pagaminti kaulo formos bandiniai iš PLA, ABS, HIPS ir PETG medžiagų. Bandinių užpildo tankis siekė ≈ 20 % paviršiaus spausdinimo sluoksnio tankio. Elementų tempimo bandymai atlikti Inovatyvių statybinių konstrukcijų laboratorijoje Vilniaus Gedimino technikos universitete. Šiame tyrime buvo parodyta spausdinimo krypties įtaka spausdintų medžiagų mechaninėms savybėms. Taip pat pateiktos eksperimentiškai nustatytos polimerinių medžiagų mechaninės savybės.


Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 585
Author(s):  
Maciej Mrówka ◽  
Anna Woźniak ◽  
Seweryn Prężyna ◽  
Sebastian Sławski

Silicones are often used for various types of coatings, but due to their poor mechanical properties, they often require modification to meet specific requirements. At the same time, various production processes throughout the world generate different types of waste, the disposal of which is harmful to the environment. One possible solution is to use production waste as a filler. In this paper, the authors investigated how the use of metallurgical production waste products as fillers changed the mechanical properties of silicone composites prepared by casting. Composite samples were characterized using tensile tests, resilience, pin-on-disc, Schopper–Schlobach abrasion, hardness, and density measurements. Based on the obtained results, the authors assessed the effect of each of the fillers used in different weight proportions. The results showed that the silicone composite filled with 5 wt% zinc dust showed the lowest decrease in tensile strength and Young’s modulus, with a simultaneous significant reduction in abrasion compared with the reference sample. This research shows that zinc waste can be successfully introduced into a silicone matrix in cases where it is important to reduce abrasive wear.


2016 ◽  
Vol 879 ◽  
pp. 471-476 ◽  
Author(s):  
Jan Džugan ◽  
Pavel Konopík ◽  
Radek Procházka ◽  
Zuzanka Trojanová

The main reason why new technologies and treatment procedure are being developed is to attain special mechanical properties. However, these developments are nowadays done on a small material volume either using some laboratory simulators, applying sever plastic deformation procedures or chemical composition screening for multicomponent alloys development by laser or electron beam melting. In all these application a small volume of the material assessed is available and standard procedures for crucial mechanical properties determinations are not applicable. Thus small size techniques should be applied. There has been extensively used small punch test technique (SPT) for those cases in recent years. This technique is mainly based on the evaluation using correlation between standard and SPT tests for considered material. In cases when insufficient material volume is available, those correlations cannot be established and thus comparative evaluation only can be carried out. This kind of evaluation is insufficient for the contemporary purposes, when full material potential is to be utilized. Therefore, procedures providing results directly comparable with standard specimens are being developed. Fundamental properties are those determined from tensile tests. The current paper is presenting application of developed miniature tensile test specimen method to materials after SPD processes. Quasi static properties determination is shown here for Magnesium and Titanium alloys for ECAP and Rotary Swaging SPD techniques. The results obtained from testing can be used not only for a direct material properties assessment and comparison, but also as input data for FEM codes, significantly increasing the materials considered application potential assessment.


2013 ◽  
Vol 592-593 ◽  
pp. 805-808 ◽  
Author(s):  
Barbara Romelczyk ◽  
Tomasz Brynk ◽  
Rafal M. Molak ◽  
Anna Jastrzębska ◽  
Katarzyna Nowak ◽  
...  

Miniaturized Disc-Bend Test (MDBT), also called the Small Punch Test (SPT) is used for characterizing the mechanical properties of metals, when only a small volume of material is available. This study was dedicated to investigating the mechanical properties of AZ91 magnesium cast alloy. The casts were prepared via gravity sand casting and have sections with different wall thickness. The examined samples were cut out of 30 mm and 10 mm thick walls. The correlation between results obtained from the tensile tests and MDBT was determined.


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