scholarly journals Effect of Delta Current and Delta Current Frequency on tensile properties and microstructure of Gas Tungsten Constricted Arc (GTCA) welded Inconel 718 sheets

2019 ◽  
Vol 28 (1) ◽  
pp. 186-200 ◽  
Author(s):  
Tushar Sonar ◽  
Visvalingam Balasubramanian ◽  
Sudersanan Malarvizhi ◽  
Thiruvenkatam Venkateswaran ◽  
Dhenuvakonda Sivakumar

AbstractInconel 718 is a nickel-based superalloy which finds major applications in lightweight welded frames and other parts in gas turbine engines. This alloy is frequently joined by gas tungsten arc welding (GTAW) process for clean and precise welds. However, the weldability of Inconel 718 alloy is limited by the high heat input and slower cooling rate in GTAW process. It leads to the segregation of alloying elements and detrimental laves phase formation in weld metal which significantly reduces the tensile properties of the welded joints. To overcome this problem, a newly developed gas tungsten constricted arc welding (GTCAW) process is used for joining Inconel 718 alloy. The main effect of Delta Current (DC) and Delta Current Frequency (DCF) on the tensile properties and microstructure of GTCA welded 2 mm thick Inconel 718 alloy sheets was investigated. Superior tensile properties were exhibited at Delta Current of 50 A and Delta Current Frequency of 4 kHz due to the refinement in fusion zone. Delta Current and Delta Current Frequency showed deleterious effect at higher levels due to the high heat input.

2020 ◽  
Vol 62 (11) ◽  
pp. 1099-1108
Author(s):  
Tushar Sonar ◽  
Visvalingam Balasubramanian ◽  
Sudersanan Malarvizhi ◽  
Annamalai Nagar ◽  
Thiruvenkatam Venkateswaran ◽  
...  

Abstract Inconel 718 is a nickel-based superalloy, typically used in high temperature aerospace applications due to its exceptional mechanical properties and weldability. However, it is susceptible to solute segregation and coarser interconnected laves phase evolution in weld metal due to the high heat input in the gas tungsten arc welding (GTAW) process which drastically reduces the tensile properties of welded joints. It is also susceptible to HAZ microfissuring and liquation cracking issues owing to the evolution of low melting temperature eutectic film at the grain boundaries. To overcome this problem, a newly emerged novel gas tungsten constricted arc welding (GTCAW) process, principally differentiated by magnetic arc constriction and high frequency accentuation of the arc, is used to join Inconel 718 superalloy. The primary objective of this investigation is to evaluate the microstructural characteristics and tensile properties of GTCA welded Inconel 718 superalloy sheets (2 mm thick), fabricated using optimized process parameters, and compare its performance with the base metal. Results showed that GTCA welded joints exhibited 99.20 % and 73.5 % of base metal strength and ductility claiming significant advantages over the GTAW process. It is correlated to the grain refinement in the fusion zone and the evolution of finer discrete laves phase in interdendritic areas of the weld. The basic mechanism responsible for fusion zone grain refinement and corresponding influence on tensile properties of joints is also discussed in brief with regard to the mechanics of arc constriction and pulsing.


2006 ◽  
Vol 22 (02) ◽  
pp. 105-109
Author(s):  
S.M. Kelly ◽  
R.P. Martukanitz ◽  
P. Michaleris ◽  
M. Bugarewicz ◽  
T. D. Huang ◽  
...  

As thinner members are used in marine construction, the use of conventional joining techniques results in significant angular and buckling distortion due to the inherent high heat input with these processes. Several low heat input alternatives, including laser beam, gas metal arc, and hybrid laser arc welding, are explored. The paper focuses on process development, real time distortion measurements, and implementation of these processes.


2018 ◽  
Vol 7 (3.6) ◽  
pp. 206
Author(s):  
P Jerold Jose ◽  
M Dev Anand

In this research, the effects of heat input on tensile properties and microstructure were investigated for super alloy Inconel-718 sheets weld by Tungsten Inert Gas (TIG) welding process. The tensile properties and microstructure of weld joints were evaluated. The experiment was conducted with six different combinations of welding parameters like welding current, voltage and welding speed, which were give in six different welding heat input combinations of welding parameters. The experimental results shows that the welding joints weld with low welding heat input was yield higher tensile properties. From the experimentation it was understand that the tensile properties increases when the welding heat input decrease. Drastic grain coarsening was evidenced when the heat input was increases. For the weld joints experimented in this research it was also observed that amount of laves phase was increased with increase in the welding heat input which is the major fact for noticeable variation in the ultimate tensile strength of the weld joints welded by TIG welding process with different welding heat input. 


2005 ◽  
Author(s):  
S. M. Kelly ◽  
R. P. Martukanitz ◽  
P. Michaleris ◽  
M. Bugarewicz ◽  
T. D. Huang ◽  
...  

As thinner members are used in marine construction, the use of conventional joining techniques result in significant angular and buckling distortion due to the inherent high heat input with these processes. Several low heat input alternatives, including laser beam, gas metal arc, and hybrid laser-arc welding are explored. The paper focuses on process development, real time distortion measurements and implementation of these processes.


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