Papers by Keyword: Tensile Test

Abstract: The mechanical properties of solder joints are critical for the reliability and performance of miniaturized electronic devices, as these joints provide both electrical connections and mechanical support. This study investigates the effect of specimen size on the mechanical properties of a lead-free solder alloy, Innolot, with an emphasis on microstructural differences and their impact on tensile behavior. Miniaturized and large tensile test specimens were prepared, characterized, and tested to simulate real-life application conditions. Microstructural analysis revealed that miniaturized specimens contained 1–2 large grains, whereas large specimens exhibited 5–7 smaller grains in the cross-section, respectively. Tensile tests showed that miniaturized specimens had significantly lower yield strength (32.1 % decrease) and ultimate tensile strength (6.94 % decrease) but higher elongation at break (23.28 % increase) compared to large specimens. The increased variability in mechanical properties observed in miniaturized specimens highlights the influence of grain orientation and size on deformation mechanisms. These findings suggest that joint-scale mechanical properties differ from those of bulk materials and that miniaturized specimens may better represent the conditions of solder joints in practical applications.

Abstract: In this study, the behavior of biocomposites reinforced with natural fibers from African palm and sugar cane in a recycled polyethylene matrix is investigated. The aim is to analyze the rheological and mechanical properties of these materials to optimize their processability by injection. Natural fibers treated through a steam explosion process and subsequent drying and grinding were used to obtain a size suitable for extrusion. Biocomposites with different percentages of fiber (30% and 40%) were prepared and evaluated by melt flow index (MFI) and capillary rheometry tests. The results indicated a significant reduction in material fluidity with increasing fiber content, which was mitigated by the addition of a lubricant additive, stearic acid. Simulation of the injection process made it possible to determine crucial parameters such as injection pressure and filling time. Subsequently, injection tests were carried out varying the temperature and fiber concentration, followed by tensile tests to evaluate the mechanical resistance of the injected specimens. The results showed that the addition of the additive significantly improved the fluidity of the material, facilitating its injection without damaging the machinery and maintaining good mechanical properties. This study provides a solid foundation for the development of biocomposites eco-friendly with potential applications in the plastics industry.

Abstract: It is a serious problem that short carbon fiber reinforced polyamide 66 (SCFRPA66) cannot be easily shaped by 3D-printing for practical usages. In order to improve on the brittleness, homogeneous low potential electron beam irradiation (HLEBI) to both sides of 3D-SCFRPA66 samples was found to increase strain at tensile strength (εts), corresponding to homogeneous deformation and fracture strain (εf), as well as resistant energy of homogeneous deformation (Ehd), whereas the HLEBI decreased the tensile strength (σts). This improvement in ductility can be explained by lone pair electrons, dangling bond generation, shortening and relaxation of the polymeric chains by the HLEBI.

Abstract: Shielded Metal Arc Welding (SMAW) is a popular welding technology in the construction and industrial sectors due to its ease of use. Flux-cored arc welding (FCAW) has gained popularity in the construction sector and industrial settings. The Welding Procedure Specification (WPS) restricts material compatibility for FCAW due to systematic selection and qualification. Penetrant Testing exposes damage to welded specimens, ensuring they meet the standard. Non-Destructive Testing (NDT) and mechanical tests like tensile and bending tests determine the mechanical strength and weld characteristics of steel using FCAW. The results show the effectiveness of pWPS and satisfy the code and standard. Dye Penetrant Test results show no cracks and acceptable criteria for both side A and side B of the steel plate. Bending test results show expected yield points, but failures occur due to discontinuities in break force and failures in tensile strength.

Abstract: Steel hydrogen embrittlement (HE), a complex and multifaceted issue, can lead to sudden and catastrophic failure, without significant plastic deformation, making it a critical concern in the industrial sector. The present investigation focuses on the evaluation of HE effects regarding microstructure, mechanical properties degradation and type of fracture of AISI 1010 low-carbon steel, after accelerated hydrogen cathodic charging. Hydrogen was diffused electrolytically in 0.2 Μ H₂SO₄ solution, containing 3g/L of NH₄SCN, using a cathodic current density of 10 and 20 mA/cm², for 6 and 18 h. Mechanical properties were investigated through slow-rate tensile tests, as well as Charpy V-notch (CVN) impact tests, to determine the value of fracture toughness, both in uncharged and electrochemically pre-charged specimens. Vickers microhardness tests were conducted on the cross-sections of the hydrogen charged samples to evaluate embrittlement susceptibility, due to the presence of dissolved hydrogen. The microstructure modification was carried out through light optical (LOM) and scanning electron microscopy (SEM), in conjunction with an energy-dispersive X-ray detector (EDS). Slow scan X-ray diffraction (SSXRD) was also conducted for crystal structure analysis. The microstructure analysis showed the presence of large amounts of secondary cracks and cavities into the steel matrix, due to hydrogen diffusion and its accumulation at various sites. Hydrogen charging caused a significant gradual elongation decrease of the parent material, from 25% to 6.73%, in case of embrittlement at 20 mA/cm² for 18h. Accordingly, after 18 h of exposure, the impact energy decrement was determined at 31.5%, at a current density of 10 mA/cm², whereas the corresponding reduction at 20 mA/cm² reached 68%.

Abstract: The current paper focuses on enhancing the manufacturability of AZ61 magnesium alloys by heat treatment. Specimens are subjected to solution heat treatment. First, all samples underwent a 15-hour treatment at 415°C before aging at 50°C, 100oC, and 150°C. The specimens were furnace cooled and quenched after achieving the precise aging temperature. The results have been extracted from tensile and cupping tests. The outcomes of each test have been compared with the data taken without heat treatment, so the ductility increase can be observed. Tests revealed better results for furnace-cooled specimens. The increase in formability of about 9% along with a decrease in strength of only 11% is observed for 150°C aging temperature.

Abstract: In this paper, a series of tensile testing on wire drawing SUS 304 were conducted in order to meet the required specifications, thus, it can be utilized on the aircraft fighter components to remain stable and avoid shaking or vibration when the engine is operated. The studied material is expected to be used on flank airframes to improve its strength, wear resistance, corrosion, and aesthetic appearance. Series of tensile test has been conducted with universal testing machine (1 tonne) with modified jig configuration according to ASTM E8. The specimens were made according to the manufacture requirements such as wavy pin and straight pin connecting rod. The wire diameter has been drawing into the final diameter, which is Φ8.0 mm. From the tensile tests, yielding 1165.8 MPa and 1588.1 MPa, respectively. It is observed that the strength of woven SUS 304 wire drawing has reached the required specification to be manufactured in aircraft fastener. Factor of safety up to 2.0 has been acquired to the studied woven SUS 304 wire drawing.

Abstract: Laser beam welding is still the focus of research all over the world since new laser sources with more brilliance, higher power, or higher efficiency are being developed. High brilliance leads to thinner fibers when solid-state lasers are used. For welding applications, a thin beam, respective a small focus spot is recommended for low heat input resulting in less deformation. The edge preparation of the welding pieces must be as accurate as possible, and a zero gap is recommended. In earlier research, it was shown, that the gap bridging capacity could be enhanced by the wobbling of small focus spots, as well as refining the grain size in the weld zone by decreasing the focus diameter. Inventions in the optics, like the beam splitting into a core and a ring part, avoid the use of a scanner and can lead to better gap bridging. Nevertheless, the use of a brilliant beam, resulting in a small focus in combination with high power can result in very high welding velocities, just limited by the used machinery. In the present study, a disk laser with 4 kW maximum power and 100 μm focus spot was used to weld 2 mm thick magnesium AZ31 sheets at speeds up to 20 m/min. As expected, the seam width becomes smaller with raising velocity, and some underfill and access material occurred on the surface and the root of the welded sheets. Surprisingly, the texture of the weld seam changed from random at low velocity to a more pronounced texture at high speed with respect to the basal texture of the plate base material. This influences the mechanical behavior, namely the strain to fracture, of the welded joints positively. The high-speed weldments are compared to state-of-the-art weldments of magnesium AZ31, in terms of mechanical strength and elongation to fracture, based on the texture analysis.

Abstract: Magnesium alloy castings are mainly formed by the die casting method, but this method has the disadvantage that product properties such as strength vary due to many defects inherent in casting. In this study, AZX912 (a flame-retardant magnesium alloy with 2% calcium added to AZ91D alloy) was semi-solid forged using a servo press and die cushion system to stabilize product properties. Experiments were conducted to refine the α-phase and reduce the yield point, and the stirring speed was changed and its effect was investigated. Observation of the microstructure of the molded product using an optical microscope showed that the average grain size of the α-phase became smaller as the stirring speed increased. Tensile tests were conducted on specimens cut from the compacts, and the yield point increased as the stirring speed increased. This is thought to be due to compliance with Hall Petch's law. The microstructure of the molded product was observed under an optical microscope and showed a three-layer structure with a dendrite shape in the upper part (about 5%), a grain structure in the middle part (over 90%), and a chill layer in the lower part (less than 5%). Comparison of the thickness of the chill layer showed that the thickness of the chill layer decreased as the solidus ratio increased.

Abstract: Fiber optimization is one of the key factors in fabricating fiber-reinforced composites. A higher amount of fiber loading does not correspond to improved mechanical and thermal properties of composites. Consequences such as poor fiber wetting, formation of voids, and delamination may arise due to the lower amount of matrix at higher fiber loading. In this study, the loading percentage of nito fibers were varied from 5, 10, and 15 wt%. The mechanical and thermal analysis showed that the composite with the lowest fiber loading percentage showed a better performance compared to the two composites with higher fiber loading. The tensile strength of the said composite increased by 3 MPa while the onset of degradation temperature increased by 30.91°C. The SEM micrographs confirmed that the composites with higher fiber loading percentage suffered poor wettability which resulted in poor adhesion of the fiber to the matrix. The micrographs of the composite with 5 wt% showed a superb fiber-matrix bonding which resulted in a more seamless transfer of heat and stress upon heat and load application. These results proved that optimization of fiber loading percentage is an integral step to fabricate an improved composite material.