“…The equiaxed dendrites in the weld center for Ni-based superalloy filler with GTAW process have also been reported in previous research [ 20 , 37 , 38 , 39 , 40 , 41 ], and the presence of a high level of super constitutional cooling during solidification in the GTAW process has been mainly reported as an important factor which governs the formation of the equiaxed dendrites in the weld center [ 42 ]. The microstructure results obtained at the interface and in the weld center are well in agreement with previously published work by Chandrasekar et al [ 34 ] and Ramkumar et al [ 43 ]. The inter-dendritic areas show the segregation of the alloying elements as referred from Figure 5 b.…”
This article deals with the dissimilar joining of two different grade Cr-Mo steel (2.25Cr-1Mo: P22 and modified 9Cr-1Mo: P91) for power plant application. The dissimilar butt-welded joint was produced for conventional V groove design by using the gas tungsten arc welding (GTAW) process with the application of an ERNiCrMo-3 Ni-based super alloy filler. A microstructure characterization was performed to measure the inhomogeneity in the microstructure and element diffusion across the interface in a welded joint. The experiments were also performed to evaluate the mechanical properties of the dissimilar welded joint in as-welded (AW) and post-weld heat treatment (PWHT) conditions. An acceptable level of the mechanical properties was obtained for the AW joint. After PWHT, a significant level of the element diffusion across the interface of the weld metal and P22 steel was observed, resulting in heterogeneity in microstructure near the interface, which was also supported by the hardness variation. Inhomogeneity in mechanical properties (impact strength and hardness) was measured across the weldments for the AW joint and was reduced after the PWHT. The tensile test results indicate an acceptable level of tensile properties for the welded joint in both AW and PWHT conditions and failure was noticed in the weak region of the P22 steel instead of the weld metal.
“…The equiaxed dendrites in the weld center for Ni-based superalloy filler with GTAW process have also been reported in previous research [ 20 , 37 , 38 , 39 , 40 , 41 ], and the presence of a high level of super constitutional cooling during solidification in the GTAW process has been mainly reported as an important factor which governs the formation of the equiaxed dendrites in the weld center [ 42 ]. The microstructure results obtained at the interface and in the weld center are well in agreement with previously published work by Chandrasekar et al [ 34 ] and Ramkumar et al [ 43 ]. The inter-dendritic areas show the segregation of the alloying elements as referred from Figure 5 b.…”
This article deals with the dissimilar joining of two different grade Cr-Mo steel (2.25Cr-1Mo: P22 and modified 9Cr-1Mo: P91) for power plant application. The dissimilar butt-welded joint was produced for conventional V groove design by using the gas tungsten arc welding (GTAW) process with the application of an ERNiCrMo-3 Ni-based super alloy filler. A microstructure characterization was performed to measure the inhomogeneity in the microstructure and element diffusion across the interface in a welded joint. The experiments were also performed to evaluate the mechanical properties of the dissimilar welded joint in as-welded (AW) and post-weld heat treatment (PWHT) conditions. An acceptable level of the mechanical properties was obtained for the AW joint. After PWHT, a significant level of the element diffusion across the interface of the weld metal and P22 steel was observed, resulting in heterogeneity in microstructure near the interface, which was also supported by the hardness variation. Inhomogeneity in mechanical properties (impact strength and hardness) was measured across the weldments for the AW joint and was reduced after the PWHT. The tensile test results indicate an acceptable level of tensile properties for the welded joint in both AW and PWHT conditions and failure was noticed in the weak region of the P22 steel instead of the weld metal.
“…Hence, it was evident that these were traces of flux particles applied before ATIG welding which did not melt completely and was now unevenly distributed in the weld fusion zone. Ramkumar et al 20 revealed the presence of similar metal oxides in ATIG weldments. These metals form oxides which could be attributed to the higher corrosion rate in the ATIG weldment over HWTIG weldment. Figure 10. FESEM and EDS full spectrum analysis with elemental mapping of the activated tungsten inert gas weldment after corrosion. Figure 11. FESEM and EDS spot analysis of the activated tungsten inert gas weldment after corrosion.…”
Section: Resultsmentioning
confidence: 99%
“…Hence, it was evident that these were traces of flux particles applied before ATIG welding which did not melt completely and was now unevenly distributed in the weld fusion zone. Ramkumar et al 20 revealed the presence of similar metal oxides in ATIG weldments. These metals form oxides which could be attributed to the higher corrosion rate in the ATIG weldment over HWTIG weldment.…”
Section: Electrochemical Corrosion Study (Tafel Plot)mentioning
Attributed to the remarkable resistance offered against various types of corrosion, AISI 904L is used for a wide range of challenging applications. In this context, this research aims to conduct an in-depth corrosion study about the base material and weldments of 10 mm thick AISI 904L plates fabricated by autogenous activated tungsten inert gas (ATIG) welding and hot wire tungsten inert gas (HWTIG) welding techniques. The pitting resistance effective number (PREN) is analyzed to evaluate pitting corrosion resistance. The Tafel plot is drawn and evaluated for the electrochemical corrosion of base metal and weldments in a 3.5% NaCl solution, while the specimens immersed in 3.5% NaCl solution at 650oC for 24 hours are evaluated for hot corrosion behavior. Thermogravimetric analysis (TGA) is performed at 300C–9000C to study material behavior at elevated temperatures. Results indicate that the base metal, ATIG weldment, and HWTIG weldment have a PREN of 34. During Tafel plot analysis, the ATIG weldment displayed a corrosion rate of 0.02792 mm/year while the HWTIG weldment recorded 0.02091 mm/year. Corrosion rates of ATIG and HWTIG weldments during hot corrosion studies are 14.93 mm/year and 12.69 mm/year, respectively. During TGA analysis, the ATIG weldment suffered a weight loss of 12.42% while the HWTIG weldment lost only 9.68% of its weight during the process. FESEM + EDS analysis confirmed the presence of unmixed flux particles in the ATIG weldment, which could be attributed to the weldment’s poor performance. In general, this research cemented the supremacy of the HWTIG weldment over the ATIG weldment with improved corrosion resistance and thermal stability. This study also contributed to a better understanding of the corrosion behavior of AISI 904L weldments under different environments that this superior grade of stainless steel alloy may encounter during its real-life applications.
“…Devendranath Ramkumar et al performed A-TIG welding on 904L super austenitic stainless steel with the use of 85% SiO 2 + 15% TiO 2 and reported that the weld penetration increased three times as compared to the autogeneous TIG weld. A-TIG weldments failed in the weld zone in tensile testing due to the lower hardness in the weld region as compared to the base material and HAZ [7]. Monoj Kumar et al investigated the tensile properties of A-TIG in Inconel 718 joints welded using SiO 2 & TiO 2 flux.…”
This study investigates the effect of different activating flux such as V 2 O 5 , TiO 2 , MoO 3 , Cr 2 O 3 , and Al 2 O 3 on A-TIG welding process of Incoloy 800H. The influence of the flux on the depth of penetration and on mechanical and metallurgical characteristics of the weld were studied and compared with autogeneous TIG welds which were welded with the same process parameters and conditions. The use of TiO 2 flux gave full depth of penetration and the use of V 2 O 5 , Cr 2 O 3 flux gave increased penetration as compared to autogeneous TIG welds while the use of Al 2 O 3 and MoO 3 led to the detoriation of the effect.
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