Search

To reduce the erosion rates of Al–Cu (2024) alloy, a double surface process consisting of committing a Titanium coating followed by plasma nitriding was used. This treatment is carried out by depositing a thin layer of Ti on the annealed alloy surface using a DC sputtering glow discharge method, followed by plasma nitriding for 6 hours at 350 °C in a gas mixture containing 75% confidence in N2 and 25% Ar. Double coatings are made with a greatly enhanced layer depth and are formed of a multiphase layer dominated by TiN and Al3Ti. The micro hardness reaches a maximum of 152 HV, which is almost three times that of the treated alloy. When compared to uncoated AA 2024 Al alloy, the erosion resistance average of coated AA 2024 Al alloy is increased by 18%. [ABSTRACT FROM AUTHOR]

The study has established that at irradiation of the Al-10Si-2Cu alloy with a pulsed electron beam (50 J/cm2, 3 pulses, 100 µs, 17 keV, 0.3 s−1) is melted of a thin surface layer about 100 µm thick. As a result of the following fast- moving crystallization, a multiphase submicrocrystalline and nanocrystalline structure of cellular crystallization was formed. Mechanical tests of alloy samples were carried out via uniaxial tension of proportional flat samples. The testing found out that the electron beam irradiation brought about 2.2 times increase of plasticity and 1.8 times increase of strength of the alloy in relative to the alloy in the cast state. The principal revealed reasons for the improvement of plastic properties in the Al-10Si-2Cu alloy treated with a pulsed electron beam are as follows: the dispersion of a surface layer structure via dissolving and the following fast-moving crystallization of silicon crystallites and intermetallic inclusions; the formation of a submicro- and nanocrystalline high-speed aluminum structure with the cellular crystallization in the thin surface layer about 100 µm thick; the stabilization of cell boundaries by nanosized second phase inclusions. The strength augmentation in the treated alloy (if compared with the as cast state) is conditioned to the dispersion hardening caused by the precipitation of nano-dimensional second phase inclusions to interfere with the movement of dislocations. [ABSTRACT FROM AUTHOR]

Aluminium Metal Matrix Composites with silicon carbide (SiC) particle reinforcements finding have the potential to offer desirable properties suitable for applications in engineering sectors especially transportation sectors. In this review studies, the effects of the addition SiC particle on the mechanical properties and microstructure of AC4B (Al-Si-Cu) composites produced by stir casting are discussed. The mechanical properties studies such as tensile strength, hardness, and wear behavior of composites depends on the volume fraction and distribution of the silicon carbide particle reinforcement as well as the interface between reinforcement and Al matrix. Microstructural studies will carry out by optical microscope and scanning electron microscopy. Many investigative works have been done on the mechanical properties and microstructure of Al-SiCp composites, but only a few such studies linked reinforcement parameters with mechanical properties and microstructure of AC4B(Al-Si-Cu)/SiCp composites. [ABSTRACT FROM AUTHOR]

This research aimed to increase the mechanical properties of Aluminum silicone (Al-Si) alloy by adding CaO as the reinforcement. This research involved powdered snail shell as the source of CaO for 0.05% from the 1.5 kg weight of Al-Si. This research used stir casting method where 1.5 kg Al-Si was melted in a furnace then added snail shell powder then stirred for 2 minutes. After, the liquid was poured into permanent cylindric metal moulds to form a tensile test specimen. The specimens then were mechanically tested to determine the tensile result, hardness test followed by microstructure test and fracture analysis. The result showed base material has 15,65 kg/mm2 tensile strength and reduction in the sample with 750℃ pouring temperature has the tensile strength of 9,34 kg/mm2 but improved in the samples with 800℃ has the tensile strength of 9,4 kg/mm2 and 850℃ pouring temperatures has the tensile strength of 13,76 kg/mm2. The highest tensile strength was found in the base material with the value of 15,65 kg/mm2 that had smaller dendrite, brittle fracture, and flat fracture that signified brittle fracture. But hardness tester showed increase, from base material and samples with temperatures 750℃ has the hardness tester of 74 HRB increase to sample with temperatures 800℃ has value 82,33 and sample with temperatures 850℃ has value 83,67. Based on the result it can be obtained that Al-Si alloy with the variation pouring temperature 850℃ is the best variation if applied to products that require high materia hardness, supported with the macro image that showed smaller and denser grains and had evenly distributed reinforcement with smaller dendrite structure. [ABSTRACT FROM AUTHOR]

Austenitic stainless steels exhibit very good properties such as very good formability even at low temperatures, good mechanical properties and high corrosion resistance. Austenitic steels are the grades which are produced most in quantity among all stainless steels and AISI 304 is the most widely used grade among the austenitic steels. They are used widely in several industries such as chemistry and petro-chemistry industries, food processing industry, medical and dental equipments and kitchenware. However, several difficulties such as carbide precipitation in heat affected zone, and hot cracking and formation of brittle sigma phase in the fusion zone may be encountered in fusion joining of these steels. High heat inputs involved in arc welding may even increase the occurrence of these problems. Thus, successful joining of these alloys using conventional fusion welding methods is rather important. This study aims at investigating the influence of heat input on microstructural evolution in the weld region and the mechanical properties of the welded joints in gas metal arc welding of AISI 304 austenitic steel plates. For this purpose, 5 mm thick AISI 304 plates were joined using different heat input values. Detailed optical microscopy and micro-hardness measurements in addition to tensile and bending tests were carried out to study the microstructural and mechanical properties of the welded plates produced. Furthermore, it was also attempted to determine the effect of heat input on the performance of gas metal arc welded AISI304 joints. [ABSTRACT FROM AUTHOR]

In this paper effect of Alumina (Al2O3) and Boron Carbide (B4C) particulate reinforcement and rotational speed on wear and mechanical properties of Aluminum alloy based hybrid composites fabricated through stir casting route was studied. Taguchi method was employed to optimize the rotational speed and volume percentage of reinforcement particles for improving the wear and mechanical properties of surface hybrid composites. It is found that the reinforcement particles (i.e. B4C & Al2O3) reduced in size (~50μm) have negative contribution while the rotational speed has positive contribution. [ABSTRACT FROM AUTHOR]

This research aimed to increase the mechanical properties in Al-Si alloy by adding MnO nanopowder reinforcer using stir casting method. This research used MnO powder raw material, then synthesized MnO nanopowder with sintered time for 30 min, MnO nanopowder with sintered time for 60 min, and MnO doped in GO with sintered time for 60 min. Each variation of MnO nanopowder was used as reinforcing material at 0.05% from the weight of the Al-Si alloy of 1.5 kg. The stir casting method was carried out by melting the Al-Si alloy metal in the casting furnace and stirring it at the speed of 500 rpm at a temperature of 950 °C, then MnO nanopowder was added. After the stir casting process was complete, Al-Si liquid metal was poured into cylindrical permanent mold according to the shape of the tensile test specimen. The specimens were then tested by mechanical testing to determine the results of tensile strength and hardness. The results showed an increase in the mechanical properties, with the best result for mechanical properties of Al-Si Alloy was obtained by using MnO nanopowder that sintered for 60 min. This specimen had a tensile strength at 14.7 Kg/mm2 and hardness at 128.7 HV, accompanied by brittle fractograph, evenly spread grains and bigger dendrite size. [ABSTRACT FROM AUTHOR]

The residual stresses in samples of the aluminum alloy AMg6 with chemical composition (wt % Fe ≤ 0.4, Si ≤ 0.4, Mn 0.5-0.8, Ti 0.02-0.1, Al 91.1-93.68, Cu ≤ 0.1, Be 0.0002-0.005, Mg 5.8-6.8, Zn ≤ 0.2) were studied. Samples form AMg6 alloys with size 10x5x1cm were welded by electron beam welding (EBW). EBW was carried out on the ESW300 / 15-60 welding units manufactured by Leybold-Heraeus. The technological parameters of the EBW process were the following: accelerating voltage U = 55 kV; beam current I = 26 mA, welding speed V = 0,5 cm/s; 1,5cm/s. The neutron diffraction method was used to determine the residual stresses in the bulk of the material. The neutron experiments were performed on the FSD diffractometer at the IBR-2 pulsed reactor in the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research - Dubna, Russian Federation. The measured residual stresses in the welding seam and in the heat affected zone do not exceed 75 MPa. [ABSTRACT FROM AUTHOR]