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Welded joints, especially those between different types of materials, always have many problems that need to be handled to improve the quality of the welds and the life of the equipment. Welds before heat treatment appear weld stress, crystalline segregation and heterogeneous weld organization. This affects the quality of parts when working, especially those working in long-term conditions, under heavy loads, or constantly changing loads. To ensure the quality of the weld, it is necessary to heat and treat the weld immediately after the welding is completed. Weld heat treatment equipment is the solution that plays an important role in the heat treatment of welds. This study has calculated, designed and manufactured a welding heat treatment device, and at the same time, conducted testing on the device. The test results show that the homogenized microorganism no longer has the phenomenon of segregation or carbide accumulation. In the weld immediately after welding, the hardness is significantly reduced, and the impact toughness is increased. Weld heat treatment equipment is designed to meet the needs of improving weld quality. This study's weld heat treatment equipment responds well to improving weld quality. [ABSTRACT FROM AUTHOR]

This paper presents an overview of bainite transformation in low carbon steel, which is alloyed with some alloying elements such as Mn, Si, Cr. The article also presents an overview of the transformation mechanism of this steel group. From the synthesis of research works, the influence of alloying elements on steel's microstructure and mechanical properties has been determined. And the final article, the bainite microstructure of CMnSi steel was found when deforming and heat treatment. By OM, the bainite structure was found. The article presents the influence of the deformation process on the microstructure and mechanical properties of low carbon alloy steel, which heat treatment by TBF processing. The samples are deformed at different levels: 20%, 40%, and 80%. The research results show that: When the sample was deformed with 80%, the highest strength was 800MPa, the highest elongation was 36%, the product between the strength and the elongation (Rm*A) was the highest: 28774MPa*%. This alloy deformed at a level of 80%. The content of austenite in this alloy's microstructure was the highest, about 16%; the content of ferrite was 52%, with the average particle size of ferrite being 6.4 µm; the particle of residual austenite was 2 µm. The microstructure results have contributed to improving the mechanical properties of steel. The phase that improved the mechanical properties of this alloy had grain size and dispersed. [ABSTRACT FROM AUTHOR]

In recent years, the development of world shipbuilding and shipbuilding technology has set new requirements for Vietnam Shipbuilding industry, which must be gradually developed on a par with the region and the world. This requires the domestic shipping industry to quickly apply advanced technologies, shorten construction time. At the same time, the training team of highly qualified technicians and workers can be trained to proficiently use new technological equipment. The study of modern specialized equipment for construction and assembly and centering on repair of the shaft system - the main engine of cargo ships is very important.. This article examines the features, specifications, usage of laser generator- Microgage 2D to effectively apply to the process of centering and assembling main engines and axles on ships. At the same time, research and design suitable jigs for microgage 2D applications in teaching practice at Shipyard engineers. [ABSTRACT FROM AUTHOR]

The search for technical solutions to optimize the combustion chamber size as well as improve the combustion efficiency of the scramjet engine has gained many benefits from optimizing the air-fuel supersonic mixing. Indeed, the technique of increasing the mixture through optimizing the flow of air-fuel mixture by applying cavity technology is the outstanding solution. This present work reports of a passive enhancement technique of supersonic mixing of air-fuel through amplification of cavity-induced flow field oscillations. In this study, with the controlling-edge profile changes to assess the changing properties of an unstable flow on a shallow cavity at the controlling-edge. This controlling-edge modification is used to augment the stimulating way in a shear surface, and that may lead to the amplification of cavity-induced flow field oscillations. The 'reactingFoam' solver within the OpenFOAM was used to simulate the supersonic cavity induced air-fuel mixing. The pressure changes over time with time and mixing indices at various positions of cavity are analyzed. Changing the leading-edge profile of the combustion chamber has an important impact on the pressure variation as well as the efficiency of the mixing process. [ABSTRACT FROM AUTHOR]

In a flow including a free surface, an interaction relationship between objects and the free surface is seen in many cases. In recent years, research on environmental change and protection has become active, so analyzing a flow field including the free surface is one of the major issues in river engineering and marine engineering. However, in most of the previous researches, the flow field was limited to the reproduction of the simple flow field. In this study, we dealt with the flow field including the free surface around a moving object with a complicated shape. So, in order to show the change of the shape of the free surface caused by the moving object, the Interface Tracking method was adopted. In this method, in order to express how the interface moves, it is necessary to move and deform the computational grid. Therefore, the calculation method was constructed based on the Unstructured Moving-Grid Finite-Volume method, which strictly satisfies the geometric conservation law and the physical conservation law. The NACA0012 blade was placed under the free surface, and the relationship between the blade's movement and the free surface was investigated. As a result, it was confirmed that the detail change of the free surface caused by the movement of the blade. Thus, it could be shown the promising feature of the computation. [ABSTRACT FROM AUTHOR]