High temperature mechanical properties of cryogenically cooled alloy 718 weldments. (3rd May 2016)

• Record Type: Journal Article
• Authors: Manikandan, SGK.; Sivakumar, D.; Kamaraj, M.
• Is Part Of: Materials at high temperatures. Volume 33:Number 3(2016)
• Page Start: 257
• Page End: 269
• Publication Date: 2016-05-03
• Subjects: Alloy 718 -- GTA weld -- Liquid nitrogen -- Laves phase -- Tensile strength -- Direct ageing; Materials at high temperatures -- Periodicals; High temperatures -- Periodicals; 620.1121705
• DOI: 10.1080/09603409.2016.1182960
• Languages: English
• ISSNs: 0960-3409

Abstract

Abstract: The micro-segregation of niobium and Laves phase formation during Gas Tungsten Arc (GTA) welding of alloy 718 were studied by employing different cooling techniques which resulted in weld cooling rates ranging from 43.2 °C/s to 508.7 °C/s. The weld cooling rates were achieved by the combinations of modified pulse wave form, argon and helium shielding gases, copper heat sink and liquid nitrogen cooling. A combination of compound current pulse (CCP) waveform with helium shielding and liquid nitrogen cooling resulted in lesser niobium segregation and discontinuous, finer Laves particles in the interdendritic regions compared to that of the conventional constant current GTA weld metal. This process yielded better ageing response and improved high temperature mechanical properties of the weldments.