جستجوی مقالات مرتبط با کلیدواژه "اتصال نورد تجمعی" در نشریات گروه "مواد و متالورژی"

In recent years, extensive studies have been conducted on severe plastic deformation based on suitable processes for sheets and solid materials. Considering the limitations in some properties and crucial applications of titanium metal, these methods are considered intriguing avenues for enhancing the efficiency of this practical metal. Therefore, efforts have been made to investigate and develop effective severe plastic deformation processes for producing titanium samples. Severe plastic deformation is widely recognized as the primary method for producing ultrafine and nanostructured materials with high strength and hardness. This study focuses on exploring the most recent methods in this family suitable for producing nanostructured titanium samples with ultrafine grains. Furthermore, the study assesses the impact of several key severe plastic deformation methods on titanium properties, comparing them based on the advantages and disadvantages of these methods from both processing and property perspectives.

In this regard, in recent years, severe plastic deformation methods have been introduced and extensively studied. In this research, by examining and reviewing the latest studies related to the advantages and disadvantages of threemethodssimple shear extrusion, accumulative roll bonding, and equal channel angular pressing, the following results have been obtained :
All past research indicates that these three methods have a significant and positive impact on the mechanical properties of titanium metal. These positive effects show an increasing acceleration up to a certain number of passes and then reach a saturation point.
Temperature, speed, and appropriate processing are three fundamental and important factors concerning severe plastic deformation of titanium metal.
Some studies suggest that pure titanium metal can also be processed at room temperature using methods of severe plastic deformation.
The frequency of using these methods in relation to titanium metal and its alloys includes methods such as ECAP, accumulative roll bonding, and simple shear extrusion, respectively.
A noticeable weakness in most studies conducted on processed titanium using severe plastic deformation methods is the lack of investigation into the biocompatibility properties of titanium concurrently with its mechanical properties after the process.
6. It can be almost stated that in none of the studies conducted on severe plastic deformation methods, a specific industrial output has been introduced, and it remains at the level of research work.

Accumulative Roll-Bonding (ARB) process is a Severe Plastic Deformation (SPD) process run to produce Ultra-Fine Grained (UFG) sheets using intense plastic strains via rolling machine. In this research, the effect of surface condition (brushing) and annealing treatment on the fracture surface and bonding strength of the ARBed AA6061 sheets was investigated. In this regard, the specimen surfaces were first brushed in three different directions, i.e., Rolling Direction (RD), Transverse Direction (TD), and both RD and TD. The ARB process was conducted up to five cycles, and specimens were tested after the first, third, and fifth cycles. The annealing treatment was conducted for two hours at 415 °C after the first, third, and fifth cycles. The bonding strength and hardness profile in the cross-section (perpendicular to the rolling direction) were measured through peeling and hardness tests, respectively. The results show that RD is the most effective direction for brushing to achieve high bonding strength with the mean strength of 0.60 N/mm. The fracture surfaces of the specimen were observed using a Scanning Electron Microscope (SEM). The results represent the broad areas of mechanical bonding in the rolling direction. Further, post-annealing treatments are shown to increase the bonding strength

The Copper/Graphene oxide composite sheets, containing 2% graphene oxide were made by accumulative roll bonding method in four steps for the first time. The process was performed at ambient temperature and non-lubricating conditions. The initial materials were commercial pure copper and graphene oxide. In order to evaluation the produced composites the mechanical, microstructural, electrical and corrosion behavior of the produced composites were investigated at different ARB cycles. The mechanical properties of the composite were investigated by tensile, micro hardness and fractography tests before and at different stages of the process. To observe structural changes a field emission scanning electron microscopy (FESEM) equipped with an EDX spectrometer were used. The results have shown that no new phase has been produced in this composite, and only the main peak of the copper, graphene and oxygen elements could be observed in the EDX patterns.The observation of microstructure showed that in lower cycles, graphene oxide powders were more agglomerated and had non-uniform distribution and in the final stages the powders distribution was more uniformly. The fractography results revealed ductile fracture of the produced composites. The corrosion resistance and electrical conductivity of composites increased compared to pure copper

Techniques of severe plastic deformation have been of continual interest in the production of novel metallic microstructures. Among these, accumulative roll bonding and simple shear extrusion have been extensively used in modern industry. In severe plastic deformations, applied strains have higher values than usual forming methods. Accumulative roll-bonding (ARB) and simple shear extrusion (SSE) processes are two severe plastic deformation processes capable of developing nanostructures. In this research, pure commercial copper was processes with ARB and SSE processes to obtain nanostructure and improve its structure, strength and hardness. Five passes of extrusion and seven passes of rolling were applied on the specimens with the same conditions. After preparing the specimens using both methods, mechanical and structural analyses were performed to evaluate the properties. Mechanical properties were measured using standard tensile and hardness tests. The results show that hardness, yield strength and ultimate tensile strength of the extruded and rolled specimens are increased by increasing the number of cycles. It was concluded that mechanical and structural properties of the specimens produced under ARB conditions appear to be better than SSE process. The layers structures were also studied by optical microscopy.