Indian Welding Journal

P. Venkata Ramana ¹

Affiliations
1 Mahatma Gandhi Institute of Technology, Gandipet, Hyderabad – 500075, Telangana, IN

Abstract

I feel deeply honoured for being invited by the Indian Institute of Welding (IIW) to deliver the prestigious Prof.Placid Rodriguez Memorial Lecture. This is a great occasion to recall the fond memories of a renowned metallurgist, eminent scientist and technologist Prof.Placid Rodriguez and his contribution to advancement of science and technology in general and to welding fraternity in particular. This occasion becomes more unforgettable as it coincides with the Golden Jubilee Celebrations of the Indian Institute of Welding. I humbly accept this award and profusely thank the President, Hon.Secretary General, Chairman-Technical Committee and Council Members of IIW for bestowing the honour upon me and the Chairman and Managing Committee members of IIW Hyderabad Branch for having nominating me. The topic I have chosen for this lecture is on welding of ultrahigh strength steels, which is of great importance as these steels are being widely employed in aerospace and defence applications.

Keywords

Welding, Ultrahigh Strength Steel, Similar Welding, Dissimilar Welding, Testing.

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P. Venkata Ramana ¹, G. Madhusudhan Reddy ²

Affiliations
1 Mahatma Gandhi Institute of Technology, Gandipet, Hyderabad – 500 075, IN
2 Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad – 500 058, IN

Abstract

Maraging steel and medium alloy medium carbon steels exhibit their best mechanical properties such as tensile strength and toughness in their respective heat treatment conditions. Gas tungsten arc welding of maraging steel and medium alloy medium carbon steel was carried out taking both the steels in soft annealed condition. Later the weldments were subjected independently to two post-weld heat treatments, one corresponding to the maraging steel i.e. solutionising at 815°C/1 hr/air cooled&aging at 480°C/3 hrs/air cooled, and the other corresponding to medium alloy medium carbon steel i.e. quenching at 925°C/35 min/air cooled&tempering at 295°C/45 min/air cooled. The effect of post-weld heat treatments on the microstructure and mechanical properties such as hardness, tensile strength and impact toughness of the dissimilar metal welds of maraging steel and medium alloy medium carbon steel was investigated. The influence of filler materials was also studied by employing maraging steel and medium alloy medium carbon steel fillers. Maraging steel welds responded to the solutionising and aging treatment whereas the medium alloy medium carbon steel welds responded to quenching and tempering. Lowering of the hardness was observed at the interaction of maraging steel and medium alloy medium carbon steel due to the diffusion of manganese. Medium alloy medium carbon steel filler welds showed good strength and toughness properties.

Keywords

Maraging Steel, Medium Alloy Medium Carbon Steel, Gas Tungsten Arc Welding and Post-Weld Heat Treatment.

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