Fusion Welding Research

2. Experimental Work
2.1 Base Material The base material used for the investigation was a 6 mm thick plate (full size : 6 mm x 1000 mm x 1500-2000 mm Hot rolled and annealed) procured with normalized (1060 ºC – ½ h) and tempered (760 ºC – 2h) condition from M/s Mishra Dhatu Nigam Limited (MIDHANI), Kachanbagh, Hyderabad. Plates were checked with Ultrasonic Examination and found satisfactory.
Chemical composition and mechanical properties of the Modified 9Cr-1Mo (P-91) steel is given below Table 1 and 2.
2.2 Fluxes and carrier solvent
Activating flux is a mixture of inorganic material suspended in a volatile medium [28]. The use of proper welding fluxes during fusion welding helps control the composition of the weld metal as well as protect

Table 4 lists the characteristics of the experimental solvents. The viscosity of methanol is substantially higher than that of acetone and promotes the cohesive force of the mixture [30]. Consequently, the flux powder mixed with methanol has a uniform coating distribution. Moreover, a substance with a high vapor pressure at normal temperature is frequently described as volatile [30]. The vapor pressure of methanol promotes the drying time of the mixture. Flux powder mixed with methanol is easy to apply with a paintbrush to the parts to be welded [30]. Methanol provides good spreadability and coverability [30].

2.3 Bead on Plate

Single-pass, autogenous, bead-on-plate TIG welds were made along the centre-line of the test specimens. A water-cooled torch with a standard 2% thoriated tungsten electrode rod with a 2.9 mm diameter was used. The electrode tip was a blunt point with a 18-20° angle and it was extended 5-6 mm outside the nozzle. The diameter of nozzle was 8 mm. Argon of 99.999% purity was used as shielding gas. The electrode gap was measured for each new weld prior to welding to ensure that the welding was performed under the same operating conditions. During the welding no consumables were added to the weld pool. A-TIG welding was carried out using fully automated process set-up in flat (PA/1G) position. Arc length L (Distance from the tip of the tungsten to the workpiece) was kept 2-3 mm. During welding, the heat of the arc melts and vaporizes part of this