Investigation on metallurgical and mechanical behavior of thick sectioned inconel 617 weldments by laser based welding processes

Abstract

In the 21st century, the major challenge facing worldwide is to provide abundant and cheap newlineelectricity to the growing global demand and at the same time reduce pollution to preserve the newlineenvironment. Although several technologies such as solar and wind renewable energy resources newlineare in the offing with development and use, effective utilization of existing thermal power plants newlinefor prolonging their life as well as enhancing the boiler efficiency is the need of the hour. Thus, newlinefuture advanced ultra-super critical (AUSC) boilers are aimed at increasing the efficiency of coalbased newlinepower generation in the range of 46 50% with application of advanced nickel-based newlinesuperalloy materials to withstand higher temperatures (710 760and#8304;C) and pressures (25 35 MPa). newlineInconel 617 is considered one of the most promising candidate materials for AUSC boiler newlinecomponents owing to its superior high-temperature structural stability coupled with hot newlinecorrosion/oxidation and creep resistance. Fusion welding is an essential joining process for newlinefabrication and construction of boiler parts in thermal power plant. Although, several conventional newlinefusion welding processes such as SMAW, SAW, GMAW, TIG and their advanced variants are newlinecurrently in use for joining thick-sectioned boiler parts, but these multi-pass welding processes newlinecharacterized by their high heat input entail certain disadvantages such as high component newlinedistortion, excessive filler material consumption and induced high residual stresses in the newlinecomponents which deteriorate their life. newlineSingle-pass welding process employing laser heat source such as Autogenous Laser newlineWelding (ALW) and Laser-Arc Hybrid Welding (LHW) are anticipated to provide great promise newlinein these aspects. Laser welding is a fusion joining process wherein a laser beam with sufficiently newlinehigh-power density interacts with the material resulted in a high depth to width ratio weld joints. newlineLaser-Arc Hybrid Welding (LHW) technique is developed by combining the electric arc and the newlinelaser beam as heat sources in a common weld