Comprehensive Analysis of TIG Welded Inconel–718 Alloy for Different Heat Input Conditions

Abstract

In this research, the effects of heat input on tensile properties and microstructure were investigated for super alloy Inconel-718 sheets weld by Tungsten Inert Gas (TIG) welding process. The tensile properties and microstructure of weld joints were evaluated. The experiment was conducted with six different combinations of welding parameters like welding current, voltage and welding speed, which were give in six different welding heat input combinations of welding parameters. The experimental results shows that the welding joints weld with low welding heat input was yield higher tensile properties. From the experimentation it was understand that the tensile properties increases when the welding heat input decrease. Drastic grain coarsening was evidenced when the heat input was increases. For the weld joints experimented in this research it was also observed that amount of laves phase was increased with increase in the welding heat input which is the major fact for noticeable variation in the ultimate tensile strength of the weld joints welded by TIG welding process with different welding heat input.

The Effect of TIG Welding Parameters and Automatization for Non-Heat Treated Inconel 718 Sheets

“…Most of the studies on TIG welding of Inconel 718 are mainly about joining sheets thicker than 1 mm. It is observed that current values have been generally preferred up to 150 A and DCEN was decided as the current type [3,12,25,26]. In our study, current values lower than 30 A resulted in metal accumulation on weld seam and distortion existed on sheets due to excess heat.…”

“…PMZ on 30 A welded specimen is shown in Fig. 7 [13,25,28]. The microstructure of FZ had a dendritic shape on all specimens.…”

“…These zones were observed easier on colon dendrites than cellular. The brighter zones are characterised as the Laves phases [6,7,24,25].…”

Preliminary Investigation Into Mechanical Properties and Microstructural Behaviour of Inconel Alloy Under Welded and Unwelded Conditions

“…It was noticed that the joints made by low heat input possessed higher strength. Also, there was a reduction in grain size with a decrement in heat input [3]. The mixture of three oxides i.e., Cr2O3, FeO, and MoO3 was used as flux in TIG welding of Inconel 718 superalloy to check the effect on weldability, pool temperature, bead geometry, and strength of the joint.…”

“…This occurs due to the development of a strong and tight oxide scale on the surface. Although Inconel 718 may be manufactured using techniques like electric discharge machining (EDM), laser beam machining (LBM), and other methods where stresses are created during machining, it is a tough alloy to cut and has a wide variety of uses [3]. This alloy's distinctive microstructure, which is made up of precipitates, γʺ, γ´, δ, carbides, and a γ-matrix, contributes to its advanced characteristics.…”