scholarly journals The Study of the Tensile Strength of AlSi21CuNiMg Silumin in the Final Stage of Solidification and the Initial Stage of Cooling

2019 ◽  
Vol 3 (3) ◽  
pp. 57-61
Author(s):  
Remigiusz Romankiewicz

The paper presents the results of tensile strength tests of AlSi21CuNiMg silumin made on a test stand. Silumin was under examination in an unmodified state and after modification with AlCu19P1.4 master alloy in quantity of 0.2% in relation to the mass of the alloy. Using a scanning microscope, the surface fractures obtained from tensile tests were tested. The structure and profiles of fractures were examined using an optical microscope. Modification of the tested silumin resulted in a favorable fragmentation and regular distribution of the crystals of the primary silicon in the alloy structure, which led to an almost twofold increase in the strength of the silumin samples at the final solidification stage from 3.5 to 6.6 MPa. As a result of these changes, the resistance of silumin to hot cracks should increase, which is of great importance when casting hypereutectic silumin in a metal mould that strongly inhibits the shrinkage of the castings.

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 374 ◽  
Author(s):  
Fen Zhou ◽  
Huanhui Liu ◽  
Yunxing Du ◽  
Lingling Liu ◽  
Deju Zhu ◽  
...  

This paper investigates the effects of the reinforcement ratio, volume fraction of steel fibers, and prestressing on the uniaxial tensile behavior of carbon textile reinforced mortar (CTRM) through uniaxial tensile tests. The results show that the tensile strength of CTRM specimens increases with the reinforcement ratio, however the textile–matrix bond strength becomes weaker and debonding can occur. Short steel fibers are able to improve the mechanical properties of the entire CTRM composite and provide additional “shear resistant ability” to enhance the textile– matrix bond strength, resulting in finer cracks with smaller spacing and width. Investigations into the fracture surfaces using an optical microscope clarify these inferences. Increases in first-crack stress and tensile strength are also observed in prestressed TRM specimens. In this study, the combination of 1% steel fibers and prestressing at 15% of the ultimate tensile strength of two-layer textiles is found to be the optimum configuration, producing the highest first-crack stress and tensile strength and the most reasonable multi-cracking pattern.


2013 ◽  
Vol 744 ◽  
pp. 339-344 ◽  
Author(s):  
Meng Xiang Liu ◽  
Jian Mei Chen

By using some types of means such as Optical Microscope (OM), Scanning Electron Microscopy(SEM), the testing of tensile mechanical properties and the testing of friction and wear, the impacts of the Al-5Ti-1B and Al-20Sr modification on the Al-16Si-4Cu-0.5Mg-0.2Mn alloy microstructure, mechanical properties and friction properties are researched. The results turn out that the modification can significantly refine the primary silicon and the eutectic silicon in the alloy, the Al-5Ti-1B mainly refined the primary silicon in the alloy, the Al-20Sr refined the eutectic silicon; the alloy’s effect of refinement after compound modification is better than that in separate metamorphism. Modification can improve the tensile strength and elongation of the alloy: the tensile strength of the alloy has been increased by 65MPa after its compound modification; also the elongation by 0.4%. Modification can improve wear-resisting property of the alloy and also its effect of compound modification is better than that of separate metamorphism. The modification mechanism of Al-5Ti-1B is that Al3Ti and TiB2 belongs to heterogeneous nucleation; while the modification mechanism of Al-20Sr is that the strontium changes the growth pattern of Si phase.


2013 ◽  
Vol 829 ◽  
pp. 583-588 ◽  
Author(s):  
Ali Dalirbod ◽  
Yahya A. Sorkhe ◽  
Hossein Aghajani

Alumina dispersion hardened copper-base composite was fabricated by internal oxidation method. The high temperature tensile fracture of Cu-Al2O3 composite was studied and tensile strengths were determined at different temperatures of 600, 680 and 780 °C. Microstructure was investigated by means of optical microscope and field emission scanning electron microscope (FESEM) with energy dispersive spectroscopy (EDS). Results show that, ultimate tensile strength and yield strength of copper alumina nanocomposite decrease slowly with increasing temperature. The yield strength reaches 119 MPa and ultimate tensile strength reaches 132 MPa at 780 °C. Surface fractography shows a dimple-type fracture on the fracture surface of the tensile tests where dimple size increases with increasing testing temperature and in some regions brittle fracture characteristics could be observed in the fracture surface.


Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1602 ◽  
Author(s):  
Yong Hu ◽  
Tong Wu ◽  
Yue Guo ◽  
Wenyang Wang ◽  
Mingkai Song ◽  
...  

SiCp/6061Al composites have been developed and widely applied in many fields, such as automobile, aerospace, shipping, and so on. Considering heat treatment, service environment, and strength of composites, this paper comprehensively studies the mechanical properties of SiCp/6061Al composites with a large range of SiC mass fractions under T6 treatments and different tensile temperatures. SiCp/6061Al composites were successfully prepared by hot press sintering at various SiC mass fractions (0–30%), and the influences of SiC concentration and T6 treatment on the mechanical properties of composites were characterized via tensile tests at room temperature, 100, and 200 °C. Microstructure and fracture surfaces of composites with various SiC concentrations were further analyzed by optical microscope and SEM. The formula for the biggest critical reinforcement concentration for the saturated distribution of SiC is proposed to reveal the strengthening rule of different SiC concentrations. Results show that the effect of T6 treatment on the mechanical properties of composites is a marked increase in tensile strength and an obvious decrease in elongation. The increase in the SiC mass fraction, except at 30%, is able to bring an increase in tensile strength and a decrease in elongation, and the change of the elongation is insignification in T6-treated specimens. The tensile strength of T6-treated specimens decreases as temperature increases, and the composite has a maximum elongation at 100 °C.


2012 ◽  
Vol 19 (3) ◽  
pp. 531-540 ◽  
Author(s):  
Stanisław Adamczak ◽  
Jerzy Bochnia ◽  
Czesław Kundera

Abstract The paper deals with the accuracy of measurements of strains (elongation and necking) and stresses (tensile strength) in static room-temperature tensile strength tests. We present methods for calculating measurement errors and uncertainties, and discuss the determination of the limiting errors of the quantities measured for circular and rectangular specimens, which is illustrated with examples.


2017 ◽  
Vol 898 ◽  
pp. 259-264 ◽  
Author(s):  
Shao Chen Zhang ◽  
Jin Feng Leng ◽  
Chen Xue Li ◽  
Xin Ying Teng

A356.2 aluminum alloy (Al–7Si–0.35Mg) has been widely used in automotive and aircraft industries. Previous studies found that the metamorphism effect of rare earth is better than other type of elements because of long modification time and good stability. The influence of Yb addition (0%, 0.2%, 0.4% and 0.6%) and T6 heat treatment on A356.2 alloy has been investigated in this work. The microstructures and mechanical properties of the specimen after T6 treatment were examined by optical microscope, scanning electronic microscope and tensile tests. Experimental results showed that Yb could reduce the size of α-Al and change the Si morphology from needle-like to fine spheroidal particles. With the increase of Yb content, the ultimate tensile strength increased gradually. When adding 0.4%Yb, the alloy achieved the highest ultimate tensile strength (252 MPa) and hardness (97.3HB), 10.12% and 37.66% higher than the alloy with no Yb addition. Tensile fracture analysis showed that the fracture mechanism for A356.2 aluminum alloy after T6 treatment is transgranular/intergranular mixed mode of fracture.


2013 ◽  
Vol 749 ◽  
pp. 105-111
Author(s):  
Wei Yan ◽  
Yuan Hui Weng ◽  
Zong Qiang Luo ◽  
Wei Wen Zhang

The microstructures and mechanical properties of the Cu-17Ni-3Al-X alloy extruded at different temperatures were investigated by hardness and tensile tests, optical microscope and scanning electronic microscope. The experimental results showed that dynamic re-crystallization occured during the hot extrusion at 1000 . The grain size of the extruded alloy was significantly refined and the mechanical properties increased remarkably compared to the as-cast alloy. The alloy extruded at 1075 exhibited good mechanical properties with tensile strength of 994 MPa, Brinell hardness of 296 and elongation of 8.0%, which are 30%, 9% and 285% higher than that of the as-cast alloy.


2021 ◽  
Vol 904 ◽  
pp. 53-58
Author(s):  
Wen Jing Zhang ◽  
Hao Feng Xie ◽  
Li Jun Peng ◽  
Zhen Yang ◽  
Guo Jie Huang ◽  
...  

The influence of W addition on microstructure and mechanical properties of Ti-Al-Sn-Zr-Mo-Nb-W-Si high temperature titanium alloys are investigated by optical microscope (OM), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), tensile tests and large stress endurance tests at 650 °C. The results show that W is mainly solubilized in β phase. Microstructure observations indicate an obvious reduction in the size of transformed β structure (βt), primary α phase (αp) and the thickness of secondary lamellar α phase (αL), with the increase of W content. It is also observed that adding more W could improve the elongation, tensile strength and large stress rupture properties at 650 °C. However, combined with previous research, adding more β stabilizing elements could refine the size of each phase, which will be detrimental to the high temperature yield strength of the alloy. Therefore, in order to reasonably utilize the strengthening effect of W and make the alloy have high yield strength and tensile strength at 650 °C, its content should be controlled between 1 ~ 2 wt%


2021 ◽  
Author(s):  
Pankaj Sharma ◽  
Gaurav Kango

Abstract To investigate the influence of clinical mask fibers on the geotechnical properties of different interfaces. In the present study different geotechnical tests like Triaxial Shear Tests, California Bearing Ratio Tests, and split tensile strength tests were done to understand the behavior of different mix propositions containing clinical mask fiber. From the test result, it is clear that the addition of waste clinical mask fiber in different mix proportions increases the overall shear strength of the material. Also, the percentage increases in CBR value were recorded by about 40% with the addition of clinical mask fiber. In addition, from the split tensile tests results on different mix proportions, it is observed that the tensile strength value increases up to 45% to 50 % with the addition of mask fiber to respective coarser and fine grain compositions. Thus, the study confirms that clinical mask fibers have the potential to improve the geotechnical properties and can be used as fill material in different construction like retaining structures and earthen embankments.


2007 ◽  
Vol 546-549 ◽  
pp. 947-952
Author(s):  
Chun Xiang Xu ◽  
Li Ping Liang ◽  
Bin Feng Lu ◽  
Yong Jun Xue ◽  
Jin Shan Zhang ◽  
...  

Al-Ti-C-P master alloy has been successfully fabricated by SHS-melting technology. Microstructures and phase constituent of Al-Ti-C-P master alloy were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and EDS. The results show that Al-Ti-C-P master alloy comprises TiAl3, TiC, AlP and α-Al matrix. After adding 2.0 wt% Al-Ti-C-P master alloy, microstructure and mechanical properties (after T6 treating) of ZL117 alloy has been improved dramatically: The average grain size of primary silicon decreases from 260 to 35 μm, edges and angles of primary silicon are passivated, the morphology of eutectic silicon changes from large needle-like one to fine rod-like or particle-like one, and the microstructures are noticeably refined; Room temperature tensile strength changes from 168 to 260 MPa while elevated temperature tensile strength (at 300) varies from 88 to 125 MPa. Impact toughness and macro-hardness(HB) increases to 17 J/cm2 and 97 from the original 6.5 J/cm2 and 92.


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