Introduction: From a long time ago, benefiting from technology has been an inevitable thing for human interests, which is born and based on science. It can be claimed that there is harmony between ethics, science and technology, which promote each other. In this article, the researcher discusses this harmony and compatibility. Material and Methods: The current review study was descriptive and using the study of sources and research keywords among the books and articles published in the databases of Thomson Information Institute, Science Direct and Pub Med. Conclusion: As science and technology continue to advance and become more integrated into our daily lives, ethical considerations become increasingly important. For example, the rise of artificial intelligence (AI) has raised questions about the potential implications of creating machines that can make autonomous decisions and take actions. If science and technology were considered as a tool, it should have been able to subjugate humans and influence all aspects of behavior and values. While it has become a problem that eventually becomes aligned with morality by applying reason, and people now seek help from it as a tool.

The high-level radioactive waste will be encapsulated in copper canisters and stored in a deep repository. High power electron beam welding was the only viable method available at that time for welding thick section copper. In recent years, friction stir welding has been replaced with electron beam welding because of the promotion in mechanical properties and corrosion resistance of copper canisters. FSW is used in solid state, therefore residual stresses produced in the weld is less than that of other welding processes which are performed in the molten state. To obtain optimum rotational speed, FSW was carried out in copper plates with a thickness of 4 mm at a constant speed of 25 mm/minute. The temperature distribution indicated a severe increasing of temperature upon increasing the rotational speed from 900 to 1200 rpm. Also, analysis of the metallographic images showed that the grain size in the nugget zone increases by increasing the rotational speed. Vickers hardness test was conducted on the welded samples and the maximum hardness was obtained at a rotational speed of 900 rpm. Results of tensile tests and their comparison with those of the base metal showed that the maximum strength and minimum elongation are achieved at the same rotational speed.

This study conducts an experimental investigation to explore the impact of the traverse speed of a tool on the tensile strength and micro-structural peculiarities of joints attained during friction stir welding of Cu alloy namely CDA 101 at plates. In this process, other parameters including spinning speed of tool (1100 rpm) and downward force (6 kN) were kept constant. A tool with a cylindrical tapered pin geometry was made to traverse at varying speeds, from 20 mm/min to 45 mm/min. It was observed that the CDA 101 joints fabricated at 20 mm/min were entirely free of flaws, while the joints fabricated at other traverse speeds of the tool were featured several weld flaws. Grains in the center of the stir zone of the joints obtained at 20 mm/min were uniformly distributed and homogeneous due to the significant volume of frictional heat and sufficient stirring force. The highest tensile strength of 200. 65 MPa (nearly 85. 38% of base metal) was exhibited by the joint attained at 20 mm/min.

In the friction stir welding process, preferred joint property is vastly reliant on the selection of optimal welding conditions. The present study aims to use the Taguchi technique to , nd the optimal process conditions for achieving superior Ultimate Tensile Strength (UTS) in friction stir welded Aluminum Matrix Composite (AMC) joints. AMCs reinforced with rutile particles which have a potential application in the aerospace, automotive, and marine industries are used in the present work. Taguchi parametric design technique was used to identify the effect of rotational speed, tool traverse speed, and tool geometry on joint strength. Taguchi approach confined the optimum level of process variables and these variables were optimized. The investigation showed that the parameters within the selected value range will seriously affect the output. The predicted value of the output response was 155. 48 MPa, which was validated by further experiments using the optimum process variables. Analysis Of Variance (ANOVA) results indicated that the UTS of the composite joint is mainly affected by the tool traverse speed followed by rotational speed, and tool geometry. The microstructural study unveiled that grain size is dependent on process variables and , finer grains offer better joint properties.

Friction stir welding (FSW) can be defined as a green technology, because the consumption of energy during this process is less than other welding methods. In addition, during the process there is no gas, filler material or other consumables. It should be noted that, complex curved shapes are now commonly used in different industries in a bid to have lightweight structures. According to the above-mentioned descriptions, several investigations into the potential benefits of adopting Friction Stir Welding (FSW) in the production and joining different materials are being undertaken. The work presented in this paper is focused on thermal behavior of the curved FSW and its benefits for the green technology. Due to the robust nature of FSW process aluminum 6061-T6 alloy has been selected as the welding material. The results of the study showed that, the total peak temperature value of 300° C happened at time, t = 3 s at the plunge stage (outside of the welding seam). Meanwhile, at the dwell stage (between t = 3 s to t = 5 s), there is a stable situation in the amount of the generated heat from the plastic deformation as well as the contact shear stress at the tool-workpiece contact interfaces, thus the interfacial temperature is found to be stable. By the end of the dwelling step, the total generated heat is stable to the maximum value of 300° C. At the step time of t = 12. 8 s, the temperature is distributed asymmetrically across the workpiece until the time step of 19. 6 s which at this point the asymmetric contour expanded in the stir zone.

Friction Stir welding (FSW) is a solid state technique that was invented to eliminate the limitations of welding of aluminum alloys. In the present study numerical simulation of friction stir welding and friction stir spot welding (FSSW) of AA6061-T6 aluminum alloy by pinless tool which has an embedded part with same material of the workpiece was performed in four different diameters. The temperature peak generated in the process was recorded for all simulation states and compared with previous experimental data for validation purposes. It has been found that in the FSSW process, the heat generation and temperature increase is higher than the FSW process, which is due to the Lack of transitional speed in this case and the increase in heat in a smaller volume section. Investigation of the vertical reaction force of tool was performed in FSSW, it was observed that if an embedded part in tool is used, the peak force is reduced and the amount of this decrease will increase with increasing the diameter of the embedded aluminum section. In the case of using d10 tool, the peak force compared to the d0 tool was about 10% lower.

Friction stir welding process is solid state welding method that does not have many common defects in fusion methods. In this method for creating optimum weld, some parameters should be optimized, such as welding tool geometry, rotational speed and travel speed. The aim of this study was to investigate the effect of rotational speed on microstructure and mechanical properties of friction stir lap welding AA5456 in rotary state to optimize the parameter values. For this purpose, Welding process was performed in rotating state, rotating tool was plunged from the cold-worked tube (AA 5456-H321 with 5 mm thickness) surface into the surface of Annealed tube (AA 5456-O with 2. 5 mm thickness) and lap joints were produced by rotational speeds of 300, 500, 700 and 900 rpm and welding speed of 45 mm/min. Macro and microstructure of weld cross sections by optical microscopy (OM) and scanning electron microscopy (SEM) were studied. Then the hardness profile and tensile shear test were obtained and compared to another. Finally the fracture surfaces of some samples were examined by using a scanning electron microscope (SEM). The Macro and microstructure results show that increasing of rotation speed, increases the vertical flow of material, the height of hook as well as fine-grained sediments in the nugget zone. Increasing the rotational speed, decreases hardness of weld nugget. The results of tensile shear test show that the welding parameter of (700 rpm-45 mm/min) is the optimal combination of parameters in this study.