The present study reported the optimization of process parameters such as current and welding speed to achieve maximum penetration in the bead on plate Gas Tungsten Arc Welding (GTAW) of super-duplex stainless steel thick plates by autogeneous-automatic mode. Two factor three level Taguchi L9 orthogonal array was employed to determine the maximum penetration. A maximum penetration of 3.4439. mm with a heat input of 1.17. kJ/mm was obtained on employing a current of 250. A and a welding speed of 150. mm/min. Experimental investigations including microstructure and mechanical properties characterization of the weldments were determined from the established optimal parameters. The results showed that the tensile strength and the impact toughness of the joints obtained from autogeneous GTAW process were found to be 851. MPa and 150. J respectively. © 2014 Elsevier Ltd.

Devendranath Ramkumar K

Department of Manufacturing Engineering

School of Mechanical Engineering

Vellore Campus

Arivazhagan N

Siva Shanmugam G

Department of Software Systems

School of Computer Science and Engineering

Mishra D

Ganesh Raj B

Vignesh M.K

Thiruvengatam G

Sudharshan S.P

Rabel A.M.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Materials & Design (1980-2015)

The present study centered on the effect of welding induced metallurgical changes on the mechanical properties and corrosion behavior of super duplex stainless steel (SDSS) weldments. The weld joints dealt with in the study has been fabricated through use of filler metal ER 2594 using gas tungsten arc welding process. Microstructural investigation in the weldment exhibited the evolution of austenite (gamma) phases in different morphologies such as grain boundary austenite, needle like elongated austenite (Widmanstätten structure) and intragranular austenite particles. Mechanical properties of the weldments were obtained and compared with the parent metal behavior by conducting Vicker's micro hardness assessment, Charpy impact toughness investigation, tensile and three-point bend experiment. Cyclic polarization curves revealed higher corrosion resistance for the weldment than the parent metal in NaCl corrosion medium. Nickel enriched filler ER 2594 led to the nucleation of additional gamma phases in the fusion zone which are electrochemically more resistant than the delta ferrite phases. Moreover, accelerated stress corrosion cracking (SCC) test proved the SCC resistance of both parent metal and weld regions by protecting the surface without nucleation of any kind of fissures or cracks. © 2018 IOP Publishing Ltd.

Materials Research Express

Analysis of structure property relationship of super duplex stainless steel AISI 2507 weldments for severe corrosive environments

Alloy 686 is a highly corrosion resistant 21st-Century Nickel based superalloy derived from Ni-Cr-Mo ternary system. The alloying elements chromium (Cr) and molybdenum (Mo) are added to improve the resistance to corrosion in the broad range of service environment. The presence of a higher percentage of alloying elements Cr and Mo lead to microsegregation and end up with hot cracking in the fusion zone of Nickel-based superalloys. However, there is scanty of information regarding the welding of alloy 686 with respect to the microsegregation of alloying elements. The present study investigates the possibility of bringing down the microsegregation to cut down the formation of secondary phases in the fusion zone. The weld joints were fabricated by Gas Tungsten Arc Welding (GTAW) and Pulsed current gas tungsten arc welding (PCGTAW) with ERNiCrMo-10 filler and without filler wire (autogenous) mode. The microstructural properties of the weld joints were studied with optical and Scanning Electron Microscope (SEM). The joints fabricated by pulsed current (PC) technique shows refined microstructure, narrower weld bead and practically no heat affected zone (HAZ). Scanning Electron Microscope demonstrates the presence of secondary phases in the interdendritic regions of GTAW case. Energy Dispersive X-ray Spectroscopy (EDS) analysis was carried out to evaluate the microsegregation of alloying element. The results show that the segregation of Mo noticed in the interdendritic zone of GTAW both autogenous and filler wire. Tensile and Impact tests were done to evaluate the strength, ductility, and toughness of the weld joints. The results show that the PCGTA helps to obtain improved strength, ductility and toughness of the weld joints compared to their respective GTAW. Bend test did not lead to cracking irrespective of the type of welding adopted in the present study. © 2017 Elsevier B.V.

Materials Science and Engineering: A

Development of welding technology for improving the metallurgical and mechanical properties of 21st century nickel based superalloy 686

In the present study, an attempt has been made to join 5-mm-thick plates of Inconel X750 using autogenous tungsten inert gas (TIG) welds without and with the use of activated compound flux mixture that contains 50%SiO2 + 25%TiO2 + 25%MoO3. The welded coupons were subjected to direct aging at 705 °C for 22 h. The interfacial and fusion zone microstructures were compared for both as-welded and direct aged coupons. It is assimilated that the fusion zone is enriched with Cr23C6 at the grain boundaries along with polygonal γ′ precipitates upon direct aging. Tensile studies show the fact that the fractures occur at the fusion zones of the joints both in as-welded and direct aged conditions. The joint strengths of the autogenous TIG weldments without and with flux addition were reported as 946 and 1162 MPa in the directly aged conditions, respectively. Studies also attested that there is an increase in the tensile strength by 54% of the autogenous weldment employing compound flux upon direct aging compared to as-welded conditions. Further, the fusion zones of both the conditions and the parent metal were subjected to 3.5%NaCl environment. Potentiodynamic polarization plots clearly envisaged that the fusion zone in the directly aged condition exhibits better corrosion resistance than that of the as-welded ones. © 2017, Springer Science+Business Media, LLC and ASM International.

Metallography, Microstructure, and Analysis

Characterization of Microstructure, Tensile Strength and Corrosion Behavior of Autogenous GTA Welds of Inconel X750 With and Without Activated Compound Flux

In the present study, three different fluxes namely NiO, MoO3 and SiO2 were employed to investigate the weldability of super-duplex stainless steel (UNS S32750). Bead on trial studies were conducted to determine the effect of welding current on the depth of penetration and depth to width (D/W) ratio. The studies demonstrated that complete penetration could be achieved in a single pass with the use of activated flux. Microstructure studies showed the formation of coarser grains of ferrite along with three different types of austenite which are Widmanstätten, intra-granular and grain boundary austenite in the fusion zones of all the weldments. Oxygen content and ferrite count analysis were also carried out at the fusion zones of the weldments. Tensile studies inferred that the tensile failures occurred at the weld zone for all the cases. The joint efficiencies of the activated flux tungsten inert gas (A-TIG) weldments employing NiO, MoO3 and SiO2 flux were reported to be 91.6%, 87.4% and 93.06%, respectively. The impact toughness of the A-TIG weldments was found to be lower than that of the base metal (82 J). Potentiodynamic polarization studies were also performed to investigate the corrosion behaviour of the welds in 3.5% NaCl environment. © 2016 The Society of Manufacturing Engineers

Journal of Manufacturing Processes

Studies on the structure–property relationships and corrosion behaviour of the activated flux TIG welding of UNS S32750

This research work articulated the effect of SiO2 flux assisted tungsten inert gas (TIG) welding on the microstructure and mechanical properties of marine grade stainless steel weldments, such as super-duplex stainless steel (UNS S32750) and austenitic stainless steel (AISI 316L). The studies showed that the use of flux decreased the heat input required to obtain complete penetration. Microstructure studies revealed the presence of ferrite at the heat affected zone of AISI 316L and the fusion zone which obviated the hot cracking tendency. Tensile studies corroborated that the joint strength was sufficiently greater than that of the parent metals. Impact toughness slightly impoverished owing to the presence of large platelets of Widmanstätten austenite in the fusion zone. The study also explored the structure-property relationships of the flux assisted weldments using the combined techniques of optical and scanning electron microscopy analysis. Owing to the better metallurgical and mechanical properties, this study recommends the use of SiO2 flux for joining the dissimilar metals involving austenitic and super-duplex stainless steels. © 2015 Elsevier B.V.

Investigations on structure–property relationships of activated flux TIG weldments of super-duplex/austenitic stainless steels

This paper investigates the weldability, metallurgical and mechanical properties of the UNS 32750 super-duplex stainless steels joints by Gas Tungsten Arc Welding (GTAW) employing ER2553 and ERNiCrMo-4 filler metals. Impact and tensile studies envisaged that the weldments employing ER2553 exhibited superior mechanical properties compared to ERNiCrMo-4 weldments. Microstructure studies performed using optical and SEM analysis clearly exhibited the different forms of austenite including widmanstatten austenite on the weld zone employing ER2553 filler. Also the presented results clearly reported the effect of filler metals on strength and toughness during the multi-pass welding. This research article addressed the improvement of tensile and impact strength using appropriate filler wire without obtaining any deleterious phases. © 2014 Elsevier Ltd.

Materials & Design

Characterization of weld strength and impact toughness in the multi-pass welding of super-duplex stainless steel UNS 32750

Welding Metallurgy and Weldability

Journal of Materials Engineering and Performance

Evaluation of Microstructure and Mechanical Properties in Dissimilar Austenitic/Super Duplex Stainless Steel Joint

The effect of gas tungsten arc welding and pulsed-gas tungsten arc welding processes’ parameters on the heat affected zone-softening behavior of strain-hardened Al–6.7Mg alloy

Journal of Materials Processing Technology

Effect of welding speed on microstructures, mechanical properties and corrosion behavior of GTA-welded AISI 201 stainless steel sheets

Effect of optimal weld parameters in the microstructure and mechanical properties of autogeneous gas tungsten arc weldments of super-duplex stainless steel UNS S32750

Journal	Data powered by TypesetMaterials & Design (1980-2015)
Publisher	Data powered by TypesetElsevier BV
ISSN	0261-3069
Open Access	No