The present study aims at a detailed investigation of microstructure, residual stress and evaluation of microhardness of electron beam surface remelted Inconel 718 alloy using an indigenously developed electron beam welding unit (with a capacity of 80 kV acceleration voltage and a power of 12 kW). Electron beam surface remelting has been carried out at a constant voltage of 40 kV with varying scan speed from 500 to 1000 mm/min. The detailed study involves understanding of the effect of process parameters on the surface roughness, microstructure, residual stress, and hardness of the melt zone. Surface remelting leads to a significant refinement of microstructure with the presence of γ primary dendrites, fine precipitates of Ni₃(Al,Ti) (γ′), and MC (metallic carbides). Due to microstructural refinement and presence of fine precipitates, there is an introduction of residual compressive stress and improvement in hardness. Finally, a detailed study of the effect of process parameters on the microstructure, residual stress and microhardness has been undertaken to optimize the process parameters for electron beam remelting of INCONEL718.

Graphical abstract

中文翻译：

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电子束表面重熔Inconel 718高温合金的研究

本研究旨在使用本地开发的电子束焊接装置（容量为80 kV加速电压和12 kW功率）对电子束表面重熔的Inconel 718合金的显微组织，残余应力和显微硬度进行详细研究。电子束表面重熔已在40 kV的恒定电压下进行，扫描速度从500到1000 mm / min不等。详细的研究包括了解工艺参数对熔体区域的表面粗糙度，微观结构，残余应力和硬度的影响。表面重熔可导致存在γ初生树枝状结晶，Ni _3的细小析出物，从而显着改善微观结构。（Al，Ti）（γ'）和MC（金属碳化物）。由于微结构的细化和细小析出物的存在，引入了残余压应力并提高了硬度。最后，对工艺参数对组织，残余应力和显微硬度的影响进行了详细研究，以优化INCONEL718电子束重熔的工艺参数。

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