Mechanised TIG Welding Gives Consistent Bead Geometry, A Case Study

Abstract

In the present study, TIG (Tungsten Inert Gas) bead-on-plate welding is carried out on grade P91 steel plates of size 100 mm x 50 mm x 6 mm. Grade P91 steel, is basically a Creep Strength-Enhanced Ferritic Steel (CSEF) known as the modified 9Cr-1Mo-V and is designated as P91 steel for Plate (A 387/A387M). The experiment is conducted with pure argon gas, without any filler material. Three control parameters (current, travel speed and gas flow rate) are taken in to consideration for autogenous fusion arc welding. In TIG welding, when the movement of either the torch or the workpiece is manually controlled, the electrode gap and the travel speed is difficult to control. The quality of the weld bead characteristics, thus, is affected. A setup with a motor-controlled travel-speed machine has been fabricated to avoid human errors during welding. The responses, weld bead geometry (in terms of bead width, depth of penetration), weld area, and width of Heat Affected Zone (HAZ) width have been measured and compared for both manual as well as mechanized welding. It has been found that the bead geometric parameters are more consistent when welded with the mechanized setup compared to manual welding.