{"references": ["S. Mukhopadhyay, T.K. Pal (2006) Effect of shielding gas mixture on\ngas metal arc welding of HSLA steel using solid and flux cor wires. Int J\nadvanced Manufactured Technology 29: 262-268", "Varga T, Konkoly T, Straube H. Investigation on microstructure,\ntoughness and defect tolerance of gas metal arc weld. IIW Document.x-\n1205-90", "Vaidya VV (2002) Shielding gas mixture for semiautomatic welds.\nWelding J 81(9):43-48", "Lathhabai S, Stout RD (1985) Shielding gas and heat input effects on\nflux-cored weld metal properties. Welding J 64(11):303-S-313-S", "Lesnewieh A (1990) An overview of arc welding process and joining of\nHSLA Steels. In: proceedings of the international conference on the\nmetallurgy, Welding and qualification of microalloyed (HSLA) steel\nweldments, Nov 6-8", "Barboo FJ, Krauklis P, Easterling KE (1989) Mater Sci Technology\n5:1057-1068", "Kluken AO, Grong O (1989) Mechanisms of inclusion formation in\nAlTi-Si-Mn deoxidized steel weld metals.Metall Trans A 20A:1335-\n1349", "Farrar RA (1976) The role of inclusion in the ductile fracture of weld\nmetals. Welding metal Fabrication 44 (8):579-581", "Francis RE, Jones JE, Olson DL (1990) Effect of shielding gas oxygen\nactivity on the weld metal microstructure of GMA welded microalloyed\nHSLA steel. Welding J 69(11):408s-415s\n[10] Pal TK, Dutta S, Majumdar SK (1997) Effect of shielding gas\ncomposition on chemistry and mechanical properties of gas metal arc\nweld metal. Trans Indian Inst Metals 50(2-3):201-208"]}

This work presents the result of investigations aimed at determining the hardness of the welded Chromoly (A 4130) steel plate of 2” thickness. Multi pass welding for the thick sections was carried out and analyzed for the Chromoly alloy steel plates. The study of hardness at the weld metal reveals that there is the presence of different micro structure products which yields diverse properties. The welding carried out using GMAW with ER70s-2 electrode. Single V groove design was selected for the butt joint configuration. The presence of hydrogen has been suppressed by selecting low hydrogen electrode. Preheating of the plate prior to welding reduces the cooling rate which also affects the weld metal microstructure. The shielding gas composition used in this analysis is 80% Ar-20% CO2. The experimental analysis gives the detailed study of the hardness of the material.