Abstract
The metallurgical deterioration and carbon diffusion caused during welding in the vicinity of the fusion interfaces between dissimilar metals have been investigated in case of gas tungsten arc and shielded metal arc welded SA508Gr.3Cl.1 steel substrate with Ni–Fe alloy and Inconel 182. The study was conducted to investigate the effect of Ni–Fe matrix as buffer layer and SMAW process for buttering deposition on the carbon diffusion and metallurgical changes. Quantitative measurement and validation of carbon/alloying elements distribution in as-welded, thermally aged, and postweld heat-treated conditions were performed in buttering deposits by using optical emission spectrometry and electron probe microanalysis. The extent of carbon diffusion has been estimated using Groube’s diffusion couple and confirmed with microstructure microhardness and X-ray diffraction. Martensite formation has been estimated for its thickness and validated with metallurgical properties. The effect of buffer layer is significant for carbon diffusion and tempering of martensite with thermal aging, PWHT, and multipass deposition. The concentration and activity gradient of carbon has been established due to Ni–Fe matrix as buffer layer and higher dilution for buttering. The obtained results are confirming the control of carbon diffusion and lesser metallurgical deterioration in suggested buttering procedure.
Highlights
Dissimilar metal welds (DMWs) are indispensable weld joints in nuclear plants, refineries, and petrochemical industries
The metallurgical deterioration and carbon diffusion caused during welding in the vicinity of the fusion interfaces between dissimilar metals have been investigated in case of gas tungsten arc and shielded metal arc welded SA508Gr.3Cl.1 steel substrate with Ni–Fe alloy and Inconel 182
The values of carbon concentrations were considered for the calculation of diffusion coefficient of carbon from ferritic steel to buffer layer and so on
Summary
Dissimilar metal welds (DMWs) are indispensable weld joints in nuclear plants, refineries, and petrochemical industries. The ferritic steel components are usually welded with stainless steel components using Inconel 82/182 consumables. To reduce the risk of sensitization during postweld heat treatment (PWHT) in stainless steel (as a joint) and maintaining metallurgical compatibility, the lowalloy ferritic steel is often welded with Ni-base overlays. This weld overlay is termed as buttering and commonly employed with gas tungsten arc welding (GTAW). The buttered (welded) ferritic steel in PWHT/as-buttered condition is used for production of DMW with stainless steel. Inconel 82/182 fillers are expected to reduce the formation of decarburized region in ferritic steel and carburization in austenitic stainless steel [1,2,3,4,5,6,7,8,9] due to reduced diffusivity of carbon in Ni-matrix
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
