Papers by Keyword: Ultimate Tensile Strength

Abstract: We report on a comprehensive study of tensile strength and fatigue behaviour depending on process parameters and ambient temperature. For this, Polyamide-12 components are fabricated using Selective Laser Sintering. Firstly, different process parameters like, e.g, scan-speed, laser power, and applied energy density are varied. Secondly, the ambient temperature during testing is varied, evaluating the impact of decreased, respectively increased test temperatures on the characteristics of the Polyamide-12 components. For all components, the static and dynamic mechanical load behaviour is investigated, quantifying the changes in the Ultimate Tensile Strength (UTS) and the endurance limit. As the applied energy density transpires as a decisive parameter, a variation leads to significant changes in UTS and endurance limit, whereas an adjustment of scan-speed and laser power at a constant energy density do not affect the mechanical properties. Finally, the ambient temperature during testing is evaluated, demonstrating different ambient application conditions. The impact of an active cooling of the component as well as increased temperatures on the mechanical behaviour is tested, providing fundamental findings on the operating life of Polyamide-12 components.

Abstract: The present research focuses on the hot forging of 38MnSiVS5 micro-alloyed steel, examining the impact of key process variables, such as working temperature, deformation percentage and rate of cooling on mechanical properties, notably the ultimate tensile strength and impact energy. To optimize the process, Taguchi's parametric design, utilizing an orthogonal array in combination with grey relational analysis and fuzzy logic analysis, has been implemented. By applying grey-fuzzy logic analysis, the optimization of complex multiple responses is streamlined into a single grey-fuzzy reasoning grade. The study employs the Grey fuzzy logic method to concurrently optimize both responses. The grey-fuzzy reasoning grade serves as a performance index, aiding in the determination of the optimal process parameter settings for both the ultimate tensile strength and impact energy responses simultaneously.

Abstract: Reinforced plastics are widely used in various fields of technology for a wide variety of structures. They provide high strength at low density, resistance to aggressive media, low material intensity of production, high manufacturability, the ability to regulate heat and electrical conductivity over a wide range, the ability to repair without the use of special equipment, they perform in a broad range of temperatures and stresses. Reinforced polymer composites with the use of fiberglass-based textile materials as reinforcement are the most used due to their availability, low cost and high strength properties. This scientific paper presents the results of specimen tests with a substrate of various types of steel, adhesive compositions as bonding material, and fiberglass as reinforcing material. The influence of the properties of the substrate and coating materials, and the ratio of their thicknesses on the theoretical strength of the composite element was investigated. The results obtained will make it possible to clarify the design schemes and dependencies in the design and repair of structural elements with reinforced polymer coatings.

Abstract: A comparative analysis of methods for estimating the gray cast iron ultimate tensile strength σ_u by the hydraulic diameter of interdendritic space D^Hyd_IP and the volume fraction of primary austenite dendrites f_dc is performed. Almost the same accuracy of cast iron castings σ_u estimation according to both these parameters D^Hyd_IP and f_dc of the primary microstructure is shown.

Abstract: The quality of the friction stir processed (FSPed) depends on the proper combination of processing parameters. The proper combination can only be found when a series of experiments have been conducted. However, the Taguchi technique was developed as a way of reducing numerous experiments that are time-consuming and costly. This paper reports on the optimization of parameters for the FSP that is conducted underwater (SFSP) and room temperature (NFSP). The Taguchi L18 method was employed in the design of experiments. The four factors used for the analysis had three factors with three-levels and one with two levels. The parameter combinations for SFSP were different from the combination found for NFSP. The level of parameter sensitivity was found to be influenced by the processing condition.

Abstract: This paper presents the results of the investigation of the grain structure formation in the intermetallic compound Ni₃Al under conditions of its high-temperature synthesis under pressure in a powder mixture of nickel and aluminum of stoichiometric composition and the effect of grain size on the strength properties of the synthesized intermetallic compound. The grain structure was investigated by optical metallography, transmission electron microscopy, and EBSD analysis; the ultimate tensile strength of the intermetallic compound was investigated under the tension of the samples in the temperature range from 20 to 1000 °C. It was found that with a decrease in the grain size, not only does the tensile strength of the intermetallic compound multiply increases but also on the anomalous temperature dependence of the intermetallic compound strength there is a significant shift in the maximum strength value to the region of higher temperatures.

Abstract: Experiments have been performed for the butt welding of 160 mm x 90 mm x 2 mm sheets of EN AW 5754 aluminium alloy, where the friction stir welding (FSW) has been used.Referring to the parent metal, the chemical composition and the form of wrought products of the aluminium alloy EN AW 5754 is presented, according to the standard EN 573-1:2005, respectively EN 573-3:2013. The mechanical properties of EN AW-5754 (Al Mg3) sheets are presented, according to EN 485-2:2016. The experiments have been conducted on the own equipment for friction stir welding, type FSW-4kW-10kN, to execute 8 (eight) FSW test pieces, according to EN ISO 25239-4. A quenched FSW tool, own-made of C 45 grade steel, EN 10083, has been used. The parameters of the FSW tests are shown. As main parameters, the rotational speed of the FSW tool was in the range n = 800 – 1200 rev/min, respectively the travel speed was in the range v = 50 – 200 mm/min. The run of the joining experiments is described and the joining test pieces are presented in figures. The ultimate tensile strength of the parent metal (σ_min,pm) is based on the specified minimum tensile strength of the ”O” condition of the parent material, respectively this value is also required for the weld, that is σ_min,w = 190 MPa. The specimens T1.0, T1.1, T2.1, T2.2, T3.1, T3.2, T4.1, T4.2, T5.1, T5.2 și T6.1 are adequate and accepted by this tensile test. The specimens T1.2, T6.2, T7.1, T72. and T8.1 can be accepted, if higher properties are achieved with a full postweld treatment. Another possibility is a lower extent of the minimum tensile strength of the weld that shall be in accordance with another design specification, for example σ_min,w = 145 MPa. By the correlation of the FSW parameters with the results of the tensile test, the ranges for the main parameters with adequate values of the ultimate tensile strength are established: n = 800 – 1000 rev/min and v = 50 – 100 mm/min. By the conclusions, the main aspects of the execution of the FSW test pieces, as well as the results of the tensile tests are selected. The involved industrial areas of the applications are: electro-technique, electronics, manufacturing, shipbuilding and automotive industries. The FSW process is ecological, because it neither uses, nor produces hazardous substances. The references consist of 12 titles.

Abstract: An artificial neural network (ANN) model has been developed for the analysis and simulation of the correlation between the chemical composition and mechanical properties of high strength low alloy (HSLA) steel X70. The input parameters of the model consist of the base metal chemical composition (C, Si, Mn, the sum of Cr+Cu+Ni+Mo, the sum of Nb+Ti+V, carbon equivalent CEpcm) and the yield strength (YS). The outputs of the ANN model include the ultimate tensile strength (UTS) of the test material. Scatter plots, correlation coefficient (R) and mean relative error (MRE) were used to assess the performance of the developed neural network. Interestingly, the model output is efficient to calculate the mechanical properties of high strength low alloy steels, especially the ultimate tensile strength as a function of chemical composition and yield strength of the used material. The obtained results are in a good agreement with experimental ones, with high correlation coefficient and low mean relative error. The predictions accuracy of the developed model also conforms to the results of mean paired T-test.

Abstract: Austempered ductile iron (ADI) has been widely used in various industries due to its excellent combination of high strength, ductility and good wear resistance. The tensile behavior of an unalloyed commercial ADI with a multiphase structure designed by a novel multi-step austempering treatment is investigated. The developed austempering process consists of austenitizing at 890°C for 20min, then initial rapid quenching to 180°C, and isothermal holding at 190, 220, 250°Cfor 120min, and finally air cooling to room temperature. The optimum mechanical properties with an ultimate tensile strength of 1350MPa, a yield strength of 1090MPa, as well as an elongation of 3.5% is achieved at 220°C. This is attributed to a synergistic strengthening effect of multiphase structure including a prior martensite with fine needle bainitic ferrite and film retained austenite.

Abstract: To study the effect of cooling speed on the microstructure and mechanical properties of Sn-0.7Cu-0.05Ni solder alloy, molten alloys were cooled at two different rates, using water-cooling and mold-cooling. The mechanical properties of the obtained alloys were analyzed with a universal testing machine (UTM) and by Vickers microhardness testing (HV). The microstructures were characterized using an optical microscope (OM) and energy dispersive X-ray spectroscopy (EDX).The melting point was ascertained by differential scanning calorimetry (DSC). The cooling rate of the water-cooled system (0.28 ^o C/s) was faster than the cooling rate of the mold-cooled system (0.05 °C/s). The grain size of the alloy produced by the faster cooling rate was finer than that of the alloy obtained from the slower cooling rate. This finer grain size gave the alloy superior ultimate tensile strength (UTS) and hardness but inferior ductility (%EL). The microstructure of both Sn-0.7Cu-0.05Ni solder alloys exhibited three phases of β-Sn, Cu₆Sn₅ and (Cu,Ni)₆Sn₅ intermetallic compounds. The melting point and undercooling of the solder alloys was 233.8 °C and 35.7 °C, respectively.