Showing 8 results for honarpishe
Mohammad honarpishe, Vahid Zandian,
Volume 14, Issue 15 (Third Special Issue 2015)
Abstract
Residual stresses reduce life time of welded joints and change the welded structure formation. Residual stress is stresses that remain in the body some specific operation like welding and is available when body is not under external loads. Different methods are available for residual stress relieved in any welded samples. In this research, samples A, B and C have been prepared and welded. Stress of Samples A and B have been relieved using heat treatment method and ultrasonic method, respectively. Also, no operation has been taken on the sample c. for different amount of residual stress of each sample, hole drilling method used and amount of residual stress in welding heat affected area of each sample determined. Results show that residual stress in ultrasonic method is for less than heat treatment method. To validate the results the x-ray diffraction method was also used and results of this method show that sample with ultrasonic stress, stress reliving had no peek in 2Ө angles, but for sample with heat treatment stress reliving had a peek in 137° that shows some residual stress.
Mahdi Pourjafari Kasmaee, Mohammad honarpishe,
Volume 15, Issue 1 (3-2015)
Abstract
Explosive welding is used for excellent bonding of similar and dissimilar materials with the wide variety of thicknesses,area dimensions and different thermal and mechanical properties. In this study, an Al/St/Al multilayer sheet was fabricated by explosive welding process and the effects of annealing temperature on the interfacial properties of explosively bonded Al/Cu bimetal have been investigated. For this purpose, hardness changes along the thickness of the samples have been measured, and the thickness and type of intermetallic compounds formed at the joining interface have been explored by means of optical microscopy (OM), scanning electron microscopy (SEM) and also energy dispersive spectroscopy (EDS). By heat treatment of the samples at 300, 350 and 400°C, it was observed that intermetallic layer was formed at the interfaces. The obtained results indicate that, with the increase of the annealing temperature, the thickness of intermetallic compounds has increased and the amount of hardness along the thickness of the joining interface has diminished. In the annealed sample at 300 °C for 60 min, it was observed that intermetallic layers have formed at the interface of Al/St bimetals. These layers consist of the intermetallic compound Al2Fe and its thickness gets to about 35 μm at some points.
Ahmad Reza Ghasemi, Mohammad Ali Moazam, Mohammad honarpisheh,
Volume 17, Issue 4 (6-2017)
Abstract
Measurement of fracture toughness is one of the quality control parameter in rail manufacturing process. Fracture toughness value is needed for designing the rail lines, analysis of defects and other common prevalent works in mechanical engineering. The goal of this research is to introduce a relation for measuring fracture toughness of rail materials with grade R260 by Charpy V-notch number. At first the fracture toughness of rail material has been determined by 3-point bending technique according to ASTM E399 in ambient temperature. The fracture energies have been measured by Charpy impact test and it has been illustrated that fracture energies have no significant change in the tests temperature limit. Relations between the chemical analysis and mechanical properties have been studied and compared with results of the other researcher. Uniaxial tension test, analysis of chemical composite, metallography and hardness test have been carried out to better study of the process. Finally a relation to connect the Charpy V-notch number and fracture toughness has been introduced and the fracture toughness of the rails material over the impact test temperature limit has been calculated. Good agreement between calculated results and result of 3-pint bending test indicate appropriate accuracy of the introduced equation.
Mohammad honarpishe, Farshad Nazari,
Volume 17, Issue 5 (7-2017)
Abstract
The contour method is a new approach to measure the residual stress and use to provide a two-dimensional map of residual stresses. In this study, residual stresses were measured in the rods which produced by hot extrusion with high reduction cross section. The rods material was 6061 aluminum alloy and the effect of annealing heat treatment has been studied on the rods. For this purpose, residual stress has been evaluated before and after annealing heat treatment and the uncertainty of the contour method calculated. The results indicate that in the rods that produced by hot extrusion with high reduction cross section, tensile residual stress is created in the rod core and by moving along radius changed to compressive residual stress such that the surface is balanced via tensile and compressive stress. The maximum tensile residual stress is formed on the rod center and performing annealing heat treatment causes to high reducing residual stress. Also the uncertainty investigation determined, the uncertainty was almost uniform on the surface and displacement error and model error sources have a same effect on the uncertainty of contour method.
Mohammad honarpishe, Hadi Mansouri, Saeed Saki Entezami,
Volume 17, Issue 10 (1-2018)
Abstract
Equal channel angular rolling process (ECAR) is one of the newest processes in the severe plastic deformation methods (SPD) that changes the mechanical properties of the sheet metal. In this study, the effects of ECAR process have been investigated on the corrosion behavior of the pure commercial copper samples. Five routs have been applied on the samples to investigate the mentioned parameters. Also, the corrosion rates were examined by the polarization and electrochemical impedance methods. The results show that the process has destructive effect on corrosion resistance of the samples. The results from SEM examination indicates that, with increasing the number of passes, the surface corrosion increases too and with increasing the passes pitting corrosion is clearly visible. Although with increasing the number of passes the uniformity of corrosion can be seen and positional mode is exited. Generally, the corrosion increases from the first pass to the second pass. Also, the more diameter and depth of corrosion is observed with increasing the pass number. The corrosion increase at the third pass and the corrosion type is pitting corrosion and uniform corrosion in the sample.
M. honarpisheh , M.h. Tavajjohi , F. Nazari,
Volume 19, Issue 2 (February 2019)
Abstract
The Constrained Groove Pressing (CGP) process is one of the most effective and newest methods of the severe plastic deformation for production ultrafine-grain metal sheets. In this research, the effect of CGP on the microstructure and mechanical properties of pure copper sheets was investigated. In order to study the microstructure of the samples, the optical microscopy was used, and tensile and Vickers micro-hardness tests were utilized for the evaluation of the mechanical properties. Investigating the microstructure of CGPed sheets determined that the CGP process has caused intense grain refinement, especially at first pass. Also, the results of mechanical properties showed that this process has considerably increased strength and hardness of the copper samples. In the numerical investigation of constrained groove pressing, effective strain and forming force were evaluated, using finite element simulation and the results indicated that with increasing number of CGP passes, effective strain, and forming force increase. Also, distribution of effective strain illustrated that the center of samples are under more effective strain that causes increasing hardness inside the samples be more than increasing hardness of the surface. Finally, a method was presented for estimating the yield strength of material, using the hardness values, and it could calculate the yield stress in different passes of process with an acceptable error of 6%.
M. Aghaei, F. Nazari, M. honarpisheh,
Volume 19, Issue 12 (December 2019)
Abstract
Quenching heat treatment is one of the most used processes in the industry, which has a great influence on the properties of materials. Accurate understanding of the effects of this process on the behavior of materials can be effective in better use of this process. In this research, the effect of quenching media on the mechanical behavior of wide used steel of AISI 1045 has been investigated and the residual stress created in the structure has been studied using the contour method. In this regard, three cooling environments of water, oil, and molten salt have been utilized, and after examining the strength and contour of hardness resulted by each cooling environment, the residual stresses have been investigated by the contour method. Also, the uncertainty of residual stresses in the environment with the most influencing factor has been evaluated. Investigation of the results shows that quenching in water can create higher hardness and strength, and more excessive compressive residual stress with greater penetration depth than the other environments. But cooling media of water creates more heterogeneous of the structure between the surface and the center of the piece, while quenching in a molten salt environment, with maintaining a structural homogeneity close to the annealing state, can increase the hardness and strength, and generate compressive residual stresses with a penetration depth of about 1.3 mm. Investigation of uncertainty for quenching in the water environment showed that the greatest error in the residual stresses was about 9%, and the error resulting from data smoothing had the most effect on the measurement of residual stresses by the cantor method.
Hamid Reza Ghahreman, Mohammad honarpisheh, Mohammad Bagher Sarafrazi,
Volume 22, Issue 5 (May 2022)
Abstract
One of the forming pipes methods is the rotary draw bending process. Today, bending of thin-walled pipes with low radius of curvature is widely used in the automotive, military and aerospace industries, which is used to bend high-strength pipes. In this paper, at first the necessary models were created to simulate the bending process of the rotary pipe, and then the necessary mechanical and physical properties for stainless steel 304 and elastomers were determined. Then, experimental and numerical study of the forming force and changes in pipe wall thickness were performed. The process simulation was analytically performed using polyurethane elastomeric mandrels and nitrile rubber based on ABAQUS finite element software on 304 steel. The results show a good agreement between simulation and experimental results. Finally, the effects of process parameters including mandrel type, pipe diameter and bending radius were analyzed on the maximum forming force by factorial analysis. The results showed that the maximum forming force for both types of mandrel materials is obtained for pipes with small diameter and high curvature radius. Also, the bending forces increase 5 times by 30%increasing the bending radius, for pipes with smaller diameters. In addition, in equal diameter and radius of bending, the bending forces in the case of using polyurethane mandrel are 25% more than nitrile mandrel.
