OPTIMIZATION OF WELDING PARAMETERS IN RELATION WITH PLATE THICKNESS AND GROOVE GEOMETRY FOR SA WELDMENTS

Abstract

An experiment has been made for the effect of varying welding current and root face, for plate thicknesses of 6, 10 and 20 mm, without any root gap and included angle 60°, On the mechanical and microstructural properties of weldments made in mild steel plates by SAW process using 4 mm diameter wire. The welding currents were varied at 400, 500 and,600 Amps, along with 2, 3 and 4 mm root faces for 10 and 20 mm; thick plates. While the 6 mm thick plate was welded in square butt position. Weldments were charectarised on the basis of Tensile properties, notch -r bar impact toughness, hardness measure-ments (Macro & Micro) and mettallographic examination. During the investigation the flux automelt grade "4" make Advani — Oerlikon was baked at 300°C for 1 hrs. and outomelt grade "C" wire 4 mm diameter, make Advani — Oerlikon were used. It was observed that increasing the current does not have or have a very little effect on tensile properties whereas it shows clearly an increasing trend for C toughness. Hardness measurements clearly indicate the maximum hardness in HAZ though effected marginally by variation of current. The lack of penetration decreased with increase in current giving an optimised values of weldin^ parametere and groove geometry (root face) as follows — N — Included angle of QV" groove = 600 -. Root face .= 2 mm — Root gap = 0 mm For plate thickness of 10 mm and more with following welding parameters. —I = 600 AMP S —V = 30 VOLTS — W.S.= 50 cm/min. The experimental data obtained has been enterpreted on the basis of microstructure and hardness along with mechanical properties of the weldmetal and Basemetal, the constituents of weldment .