Papers by Keyword: Elongation

Abstract: In the present work, Al-TiB₂ in-situ metal matrix composites were processed via master alloy route at 800°C-30 min. with 5 and 7wt% of TiB₂ particles. Microstructural characterization of the prepared insitu composites were carried out using XRD, SEM/EDX studies. X ray diffraction studies have shown the presence of Al₃Ti and TiB₂ phases, however, the presence of AlB₂ particles is also highly likely. SEM/EDX characterization revealed fairly uniformly distributed TiB₂ particles having hexagonal morphology with size distribution in the ranges between 0.5-10μm. Further, presence of TiB₂ particles in Al matrix have resulted in improvement in hardness and tensile properties of the Al matrix while decrease in ductility was observed.

Abstract: It has been reported that the elongation of the AA1050-H26 sheet annealed at 200°C is lower than that of the AA1050-H18 sheet. In this study, the effect of the annealing time at 250°C on the elongation of AA1200 alloy sheets was investigated, and the cause of the low elongation was discussed by observing the change in the microstructures before and after tensile deformation. The elongation of the samples annealed at 250°C for less than 50 min was below 1%, and this elongation was lower than the elongation of the as-rolled and annealed ones at 250°C for more than 150 min. In the samples annealed for a short time, the subgrains with diameters of 0.5~2μm formed, and Fe and Si, which were a solid solution, became segregated at the sub-boundaries. These samples were locally deformed in a stress concentrated area during the tensile deformation, and there was no significant increase in the dislocation density near the fracture part after the deformation. The cause of the low elongation was considered to be due to the dynamic recovery that locally occurred in a stress concentrated area during the tensile deformation, because dislocations introduced into the subgrains by the deformation easily moved to the sub-boundaries due to the low solute levels within the subgrains.

Abstract: The corrosion rates of rebar HRB400 in 0.5 wt.% NaCl solution were measured, and the mechanical properties before and after corrosion were tested. The results showed that, with the increase of corrosion time, the corrosion rate of rebar HRB400 increases and the corrosion becomes heavier. Meanwhile, the yield strength and tensile strength decrease, but the elongation decreases at first and then increases.

Abstract: The precipitation behavior during heat treatment and resulting mechanical properties of ASTM F 90 Co-20Cr-15W-10Ni (mass%) alloys were investigated with regards to their biomedical applications. Heat treatment was conducted at temperatures of 873 to 1623 K, for a holding time of 259.2 ks. The precipitates produced were then electrolytically extracted from the alloys and analyzed by X-ray diffraction (XRD). This revealed that the precipitates formed were an M₂₃X₆ type and/or η-phase (i.e., an M₆X-M₁₂X type). The M₂₃X₆-type precipitate was detected across the entire heat-treatment temperature range; however, the η-phase precipitate was only detected at 1073 to 1473 K, becoming dominant at 1173 to 1373 K. The formation of M₂₃X₆ type precipitates at 873 K is shown to improve the mechanical properties of this alloy, whereas the domination by the η-phase precipitate at higher temperatures causes deterioration in the ductility.

Abstract: Aggregate characteristics of shape, texture and grading influence on workability, finishability, bleeding, pumpability and segregation of fresh concrete and affects the strength, shrinkage, density, and durability of hardened concrete. About 80% of total volume of concrete consists of aggregate. Construction and durability problems have been reported due to poor mixture proportioning and variation on grading. Aggregate characteristics significantly affect the performance of Quality Concrete (QC) both in fresh and hardened state and have an impact on the cost effectiveness. Flaky and elongated particles lead to higher voids than cubical, rounded and well graded particles. The shape factor of aggregate plays a vital role in the design and performance of QC mix and it is mainly depends on the rock formation and type of crusher being used for crushing the aggregates. Flaky and elongated particles have larger specific surface area which results in higher demand of cement paste in cement concrete mix. These particles impede compaction or break during rolling and decrease the strength of the concrete structures. An attempt is made to study the effect of shape of aggregate on quality of the concrete used for the buildings and pavements. Initially an aggregate samples were collected from the stone crusher (two types) and prepared with different proportions of Flakiness and Elongation indices to conduct tests on properties of aggregates and compressive strength and flexural strength tests on concrete. The effect of different percentages from 0 to 50% of combined Flaky and Elongation Aggregates (CFEA) for quality concrete on the compressive and flexural strength of cement concrete is studied. The other properties of aggregate such as bulk density, impact value, water absorption have been studied for different shapes of aggregates. The cost analysis has been carried out with an optimum value of 30% CFEA in 1:3 proportions of flaky and elongated particles.

Abstract: 5083 aluminum alloy was processed with combined process of warm rolling and annealing. Elongation and tensile strength of samples were measured to analyze the influences of annealing temperature and annealing time on its mechanical properties.Results show that low temperature superplasticity is very sensitive to temperature. The maximum elongation for 5083 aluminum alloy reaches 443% at 250°C and a strain rate of 1×10^-3s^-1, which means that 5083 aluminum alloy exhibits excellent low temperature superplasticity. Low temperature annealing before drawing could not effectively improve the elongation.

Abstract: As a novel heat treatment process, Q&P (quenching and partitioning) process can be applied to enhance the ductility of steels. In this paper, the effects of different parameters of Q&P process (such as quenching temperature, partitioning temperature and partitioning time) on mechanical properties and microstructure of 22MnB5 steel was investigated. Analysis demonstrated that austenite can be stabilized via Q&P process and the volume fraction of retained austenite increases with the partitioning temperature and the partitioning time. The mechanical properties of the steel can be controlled to acquire the steel with excellent strength-ductility balance by Q&P process.

Abstract: The corrosion behavior of rebar HRB400 in 1.5 wt.% NaCl solution was studied, and the mechanical properties before and after corrosion were tested. The results showed that, with the increase of corrosion time from 240h to 720h, the corrosion rate of rebar HRB400 increases and the corrosion becomes heavier. Meanwhile, the yield strength and tensile strength decrease, but the elongation decreases at first and then increases.

Abstract: The microstructure and mechanical properties of as-cast Mg-5Y-(2, 3, 4)Sm-0.8Ca (wt.%) alloys have been investigated. The results show that the microstructure of as-cast alloys consists of α-Mg matrix, Mg₂₄Y₅, Mg₄₁Sm₅ and Mg₂Ca. With the increase of Sm addition, the tensile strength increases at first, and then decreases. Mg-5Y-3Sm-0.8Ca alloy has the highest strength and can be a basis for developing light structural materials.

Abstract: select ADI commonly used in engineering, set 15 sets of austempering parameters and research on the rules of their influence on the tensile strength and elongation of ADI. Through the tensile test, use ANSYS Workbench to simulate the process of tensile measurement and compare the experimental data. The results show that: longer austenitizing time leads to smaller tensile strength, whereas the elongation remains unchanged. The tensile strength reduces linearly as the austempering temperature rises while the elongation first increases and then reduces as the austempering temperature rises and peaks at 350°C. The austempering time has little influence on elongation.