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چکیده
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In this study, the cold formation of pressure vessel sheet was investigated by using open-die pressing process.. The rolling sheet of A516 Gr70 with a thickness of 45 mm was selected. The radius of the used die was 6000 mm to pressing process. The process was carried out in three passes. In each pass of the process, the sheet was placed under the force of 600 tons. The process was performed in passes 1, 2 and 3 in order to reduce the effect of the spring back and to check the effect of the repetition of formation process on mechanical properties and microstructure of the shaped sheets. The results showed that the tensile strength and yield stress and hardness are reduced at the first step of pressing process. In the following, the mechanical properties are increased by repeating the pressing process in 2 and 3 passes. Microstructural analysis showed that the order of rolling grains was disrupted and the orientation of the first grains would greatly change by performing the pressing process. By increasing the number of passes, the orientation of the grains become more uniform that causes the enhancement of mechanical properties.
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