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Cold spin bonding is a new invented method for producing layered composite tubes based on flow-forming process. Bonding strength in this process is dependent to parameters such as initial thickness, rate of deformation, bonding temperature, initial strength, heat treatment temperature, duration of heat treatment and also production parameters like feed rate and spindle RPM. In the present work, effect of rate on thickness reduction, heat treatment temperature and duration of heat treatment on bonding strength of steel and aluminum have been studied. The strength of bonding which produced by cold spin bonding has been measured by peel test and structure investigation has been done by scanning electron microscopy. Among the parameters, heat treatment temperature and after that thickness reduction rate have the most effects on bonding strength and heat treatment duration has less effect in comparison. The results show that the increase of heat treatment temperature up to a certain level increase bonding strength, but above that level the strength will decrease. . This study also has shown that the best condition occur in %50 thickness reduction, heat treatment temperature of 475 degree and 120 minutes of heat treatment in which bonding strength reaches to yield strength of base metal.

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Ironing is a conventional metal forming process for producing thin walled cans with uniform thickness components manufactured from deep drawn cups. The most important drawback of the conventional ironing is the lower thickness reduction ratio (TRR) causes needing annealing process and multi stage ironing. Recently, a new ironing process named constrained ironing was presented by the current authors to achieve an extra TRR to solve the conventional ironing problems. This process that is based on the compressive stresses makes it possible achieving high TRR without interruption for additional processing such as multi-stage ironing and annealing. In this paper, FEM simulation was performed to investigate the effective parameters. The simulation results showed that process the process load increases with increasing the friction coefficient. Also, the state of the stresses is fully compressive in constrained ironing process while it is tensile in the conventional ironing method. Thus, compressive stress components minimize formability problems, and higher thickness reduction ratio is achievable in the new ironing method. Also, experimental results showed that the tensile strength and hardness increased after constrained ironed of the deep drawn cup.

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The flow forming process is widely used in the production of axisymmetric industrial parts. The advantage of the flow forming process over other manufacturing methods is the use of simple tooling, reduced forming loads due to localized deformation, and enhanced mechanical properties and surface quality of finished parts. In this research, the warm flow forming process of AA6061-O aluminum alloy has been investigated for the first time. For this purpose, laboratory equipment and samples were designed and fabricated. In this study, the effect of temperature, thickness reduction, and number of passes (number of forming steps) on dimensional accuracy (thickness variation) and mechanical properties of warm flow formed AA6061-O alloys pipes have been experimentally investigated. The experimental results show that flow forming increases the strength and decreases the ductility of the formed pipe at all process levels compared to the initial non-flow forming pipe. However, the ductility of the pipe increases and its strength and microhardness decrease by increasing the forming temperature from 20 to 300 ° C. While with increasing the percentage of thickness reduction from 20% to 60% at a constant forming temperature, the strength and micro-hardness of the warm flow-formed pipe increases and its ductility decreases.

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Flow forming is one of the advanced methods for producing low thickness cylindrical parts. The dimensional accuracy of pipes produced by the flow forming method is much higher than other methods and this method is widely used in the aerospace industry. In this research, the effect of number flow forming passes has been investigated on the mechanical properties and microstructure of AISI4130 steel. Three stages of thickness reduction have been successfully completed and in the fourth stage, the tube was fractured. In the first stage of this pass, the desired steel thickness has changed from 14.2 mm to 9.3 mm. In the second stage, the thickness reached 2.6 mm, in the third stage to a thickness of 2.3 mm and in the fourth stage by reaching 1.8 mm thick, there has been a tear in the pipe. During the flow forming process, the maximum amount of 84.5% thickness reduction can be achieved. To achieve a higher percentage of thickness reduction, it is necessary to re-anneal the flow formed sample. To investigate the tensile properties, tensile tests have been done through both longitudinal and circumferential directions. According to the results, it was found that the flow forming operation on this steel has increased the hardness and yield, and ultimate strength of the material at every stage. Also, the hard work done at every stage on this steel by maintaining the ferritic pearlite-ferritic structure has caused finer grain structure and elongation of the grains.