Influence of electron beam welding parameters on the weld seam geometry of Inconel 718 at low feed rates

Abstract

Ni-based superalloys are well established in various industrial applications, because of their excellent mechanical properties and corrosion resistance at high temperatures. Despite the high development stage and a common industrial use of these alloys, hot cracking remains a major challenge limiting the weldability of the materials. As commonly known, the hot cracking susceptibility during welding increases with the amount of precipitation phases. Hence, a large amount of highstrength Ni-Alloys is rated as non-weldable. A new approach based on electron beam welding at low feed rates shows great potential for reducing the hot cracking tendency of precipitation-hardened alloys. However, geometry and properties of the weld seam differ significantly in comparison to the common process range for practical uses. The aim of this study is to investigate the influence of welding parameters on the seam geometry at low feed rates between 1 mm/s and 10 mm/s. For this purpose, 25 bead on plate welds on a 12 mm thick sheet made of Inconel 718 are carried out. First, the relevant parameters are identified by performing a screening. Then the effects discovered are further studied by using a central composite design. The results show a significant difference between the analyzed weld seam geometry in comparison to the well-known appearance of electron beam welded seams.

Optimization of responses in electron beam welding of inconel-718 alloy using genetic algorithm approach

“…It is reported from NSGA-II optimization results that maximum bead width is found at 4.235 and maximum depth of penetration is found at 7.341 and experiment results predicted that maximum bead width is found at 4.895 and maximum depth of penetration is found at 7.624. It is understood that 53.48% is improved enhancement in low heat welding and extends rupture life of the material [29]. As observed in Table 9 through the use of GA`s optimization technique, bead width increases from 4.235 to 4.895 for NSGA-II algorithm and depth of penetration increased from 7.341 to 7.624 for NSGA-II algorithm.…”

“…From Figure 3 it is noted that for minimum weld speed and minimum welding current give more grade value than maximum weld speed. This might be poor absorption of heat inside the gap of alloy [29]. It is observed from Figure 4 that more influencing parameter from minimum welding current and minimum weld speed.…”