Indian Welding Journal

K. Karthick ¹, S. Malarvizhi ², V. Balasubramanian ³, S. A. Krishnan ⁴, G. Sasikala ⁴, Shaju K. Albert ⁴

Affiliations
1 Centre for Materials Joining and Research, Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar - 608 002, Tamil Nadu, IN
2 Centre for Materials Joining and Research, Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar – 608 002, Tamil Nadu, IN
3 Centre for Materials Joining and Research, Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar – 608 002, Tamil Nadu, IN
4 Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam - 603 102, Tamil Nadu, IN

Abstract

In liquid metal cooled fast breeder reactors, the dissimilar joint between grade 91 ferritic steel and 316LN stainless steel is frequently encountered. For better integrity assessment, mechanical properties of each region need be evaluated. In the present investigation, dissimilar joints between grade 91 to 316LN SS were fabricated by shielded metal arc welding process using nickel based electrodes. Mechanical properties (Tensile and impact toughness) of different regions were evaluated by placing the notch at each location. Microhardness variation across the dissimilar joint was recorded. Microstructural analyses of various regions were done by optical and scanning electron microscopy. From this investigation, it is understood that the in-homogeneous mechanical properties were observed across the dissimilar joint. The development of complex microstructure at the fusion interfaces will alter the mechanical properties across the dissimilar joint.

Keywords

Welding, Dissimilar Joint, Mechanical Properties, Microstructure, Microhardness.

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R. Kamal Jayaraj ¹, S. Malarvizhi ¹, V. Balasubramanian ¹

Affiliations
1 Centre for Materials Joining & Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar-608002, Tamil Nadu, IN

Abstract

Joining of aluminium is commonly done in automobile industries because of its light weight and high specific strength. In recent days, friction stir welding (FSW) is widely preferred to join aluminium than fusion-welding processes. In this joint, grains are very fine in stir zone (SZ) compared to the other zones. Due to this extreme change in the microstructure at the SZ, the mechanical properties (tensile strength, hardness, etc) of the FSW joints are superior but the corrosion resistance of SZ is very poor. The concentration of chloride ion, exposure time and pH value are reported to be the more influencing corrosion test parameters. The present work aims to determine combination of these pitting corrosion test parameters to attain a minimum corrosion rate at the SZ of friction stir welded aluminium alloy, AA6061-T6, by response surface methodology (RSM). From the results obtained, chloride ion concentration is reportedly had higher effect on corrosion rate than the other two parameters considered.

Keywords

AA6061 Aluminium Alloy, Stir Zone, Response Surface Methodology, Pitting Corrosion Test.

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G. Vairamani ¹, T. Senthil Kumar ², S. Malarvizhi ³, V. Balasubramanian ³

Affiliations
1 Department of Mechanical Engineering, Seshasayee Institute of Technology, Tiruchirappalli, IN
2 Department of Mechanical Engineering, Anna University of Chennai, Tiruchirappalli Campus, IN
3 Centre for Materials Joining & Research (CEMAJOR), Annamalai University, Annamalainagar, IN

Abstract

Friction welding can be used to join different types of ferrous metals and non-ferrous metals that cannot be welded by traditional fusion welding processes. The process parameters such as rotational speed, friction pressure, forging pressure, friction time and forging time play the major roles in determining the strength of the joints. In this investigation, an attempt was made to develop empirical relationships to predict the tensile strength and interface hardness of friction welded dissimilar joints of AIS I304 austenitic stainless steel (ASS) and AA6082 aluminium (Al) alloy using statistical tools such as design of experiments, analysis of variance and regression analysis. The developed empirical relationships can be effectively used to predict tensile strength and interface hardness of friction welded dissimilar joints of ASS-AI at 95% confidence level.

Keywords

Friction Welding, Austenitic Stainless Steel, Aluminium Alloy, Design of Experiments, Analysis of Variance, Tensile Strength.

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S. Malarvizhi ¹, V. Balasubramanian ¹, N. Viswanathan ²

Affiliations
1 Centre for Materials Joining &. Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Annamalainagar 608002, Tamilnadu, IN
2 Department of Engineering, Defence Research & Development Laboratory (DRDL), Kanchanbagh (P.O), Hyderabad, IN

Abstract

AA2219 aluminium alloy joints without filler metal addition were produced using electron beam welding (EBW) process. Microstructure characteristics, tensile properties, fatigue strength and fatigue crack growth resistance of the welds were evaluated and presented in this paper.

Keywords

AA2219 Aluminium Alloy, Electron Beam Welding, Artificial Aging Treatment, Tensile Properties, Fatigue Performance.

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S. Malarvizhi ¹

Affiliations
1 Center for Materials Joining and Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar - 608002, IN

Abstract

Additive manufacturing (also known as 3D printing) is considered as a disruptive technology to produce limited number of high value components with topologically optimized complex geometries and functionalities that is not achievable by traditional manufacturing. Wire Arc Additive Manufacturing (WAAM) allows to produce metal components by depositing filler wire layer by layer with the help of welding arc. WAAM is a potential future process to manufacture complex parts without much of tooling required or with less material wastage. Cold Metal Transfer (CMT) arc welding technique offers high stable arc with less heat input and high welding speed which results in less distortion. The aim of this work is to optimize the critical welding parameters in CMT arc welding in order to achieve a stable arc to develop the component and to analyse the mechanical and micro structure properties fabricated using ER308L wire. In this experimental work, welding parameters in CMT process were optimized for the stainless steel component deposited using ER308L filler wire. From this investigation it was found that the weld speed, current, stick out and voltage were the most influencing parameters to achieve stable arc and for process feasibility. After the completion of fabrication, the component was tested non-destructively in order to confirm the soundness of the weld deposits and to ensure the component is free from porosity and lack of fusion between the layers. The component was sectioned and specimens were extracted from vertically at three sections (Top, middle and bottom). Mechanical properties were evaluated as per the ASTM standards. Microstructural analysis was done using optical microscopy and scanning electron microscopy. It is found that the mechanical properties and microstructural characteristics are uniform throughout the height of the component.

Keywords

Wire Arc Additive Manufacturing, Gas Metal Arc Welding, Stainless Steel, Cold Metal Transfer, Mechanical Properties, Microstructure.

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Tushar Sonar ¹, V. Balasubramanian ¹, S. Malarvizhi ¹, T. Venkateswaran ², D. Sivakumar ²

Affiliations
1 Centre for Materials Joining and Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University , Annamalai Nagar 608002, Tamilnadu, IN
2 Vikram Sarabhai Space Centre (VSSC), ISRO, Thiruvananthapuram 695022, Kerala, IN

Abstract

Inconel 718 is a nickel-based superalloy mostly used in high temperature applications in aerospace sector due to its extensive mechanical properties and weldability . Gas T ungsten Arc Welding (GT AW) process is widely used for joining of Inconel 718 alloy for cleaner , precise and high-quality welds. However , due to the high heat input and wider arc associated with this process, it is having certain metallurgical problems in welding, such as coarse dendritic structure and segregation of alloying elements in weld metal region which significantly reduces the mechanical properties of the joints. T o overcome these limitations, a newly developed Gas T ungsten Constricted Arc Welding (GTCAW) process is employed to join Inconel 718 alloy . It is the advanced configuration of GTAW process, based on magnetic arc constriction induced by high frequency pulsing of the current known as Delta Current. The main objective of this investigation is to study the effect of Delta Current Frequency (DCF) on the weldability of Inconel 718 alloy for its viability in aerospace applications. The joints welded at 4 kHz showed superior tensile properties due to the refinement of grains in fusion zone. Increase in DCF results in decrease in tensile properties of the joints due to the coarsening of dendritic fusion zone microstructure. It is attributed to the stacking of heat input during welding.

Keywords

Gas Tungsten Constricted Arc Welding, GTCAW, Delta Current Frequency, Inconel 718, T Ensile Properties, Microstructure.

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Tushar Sonar ¹, V. Balasubramanian ², S. Malarvizhi ², Namita Dusane ³

Affiliations
1 G.S.Mandal's Maharashtra Institute of Technology,Aurangabad - 431010, Maharashtra State, IN
2 Centre for Materials Joining and Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University Annamalai Nagar - 608002, Tamil Nadu State, IN
3 Department of Computer Science and Applications, Hinduja College of Commerce Mumbai 400004, Maharashtra State, IN

Abstract

The IoT (Internet of Thing) basically pertains to the concept of linking anything that is powered both to the internet and each other and simulating human intelligence by machines, particularly computer systems is artificial intelligence. It includes learning (acquisition of data and rules for exploiting the data), logic (exploiting rules to arrive at probable or definitive findings) and selfrectification. Many automatic welding machines are now connected to a computer and are fully networked and can be reached anywhere in world from a computer at any time. The first apparent use would be in the evaluation and configuration of the equipment itself, as the equipment must be regularly interfaced with a network to perform these functions. Future IoT technology for the welding sector is likely to emerge largely as part of an artificial intelligence network, as it would be extremely beneficial to control and monitor functions even though the system is not in connection with internet. Simulating human intelligence by machines, specifically computers is known as Artificial intelligence (AI). It includes learning (acquisition of data and rules for exploiting the data), logic (exploiting rules to arrive at probable or definitive findings) and self-rectification. AI is incorporated into a variety of different types of technology. AI will have IoT flexibility which would play a major role in complying the requirements of Welding Industry 4.0.

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N. Sankar ¹, S. Malarvizhi ², V. Balasubramanian ³, A. Hafeezur Rahman ⁴, V. Balaguru ⁵

Affiliations
1 Research Scholar, Centre for Materials Joining and Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Annamalainagar, IN
2 Professor, Centre for Materials Joining and Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Annamalainagar, IN
3 Professor, Head and Director, Centre for Materials Joining and Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Annamalainagar, IN
4 Scientist, Combat Vehicles Research & Development Establishment (CVRDE), DRDO, Avadi, Chennai, IN
5 Outstanding Scientist, Combat Vehicles Research & Development Establishment (CVRDE), DRDO, Avadi, Chennai, IN

Abstract

This work is aimed to investigate the arc rotation effect on mechanical properties and metallurgical characteristics of 18 mm thickness armour grade quenched and tempered (Q & T) steel joints. Mechanical properties like tensile, impact toughness and microhardness were evaluated from welded joints. Metallurgical characteristics of welded joints like macrostructure, microstructure, and weld metal chemical composition were analyzed. From the results, it is observed that the rotating arc gas metal welded (RTA-GMW) joint contain minimum heat affected zone width (1.8 mm) and exhibits better tensile properties (784 MPa) due to the decrease in heat density caused by arc rotation of the joining process. The impact toughness properties of weld joint showed 36 % improvement than the unwelded base metal. Microstructural studies also revealed higher volume percentage of fine delta ferrite (δ-Fe) with vermicular type δ-Fe morphological future in the weld joint. The rotation arc caused reduction in heat input, enhanced strength, impact toughness properties and creation of vermicular type δ-Fe morphology in armour grade Q&T steel welded joints.

Keywords

Armour Steel, Rotating Arc Welding, Mechanical Properties, Metallurgical Behaviour.

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