Abstract
Gas tungsten arc welding of CK45 and AISI304 stainless steel was performed through preparation of different types of samples using ER308L and ERNi-1 wires. Welded samples were studied by different techniques including optical metallography, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction, hardness measurements and impact test. It was observed that in the buttered specimen, the structure of the weld metal was completely austenitic while the microstructure of unbuttered sample was duplex ferritic-austenitic. M23C6-type carbides were observed within the weld metal of both as-weld specimen types. Effects of different post-weld heat treatments (PWHTs) were investigated. The experimented results concluded that simultaneous grain growth and carbides precipitation were competitive during PWHT. Also, there were not any indication related to sigma-phase in as-welded and PWHTed specimens due to their lower Cr/Ni ratios and insufficient preservation times.
Highlights
According to the fact that every part of a process system operates at a specific condition, different structural alloys such as stainless steels, low-alloy and carbon steels due to their special properties are used in the design; resultant in dissimilar metal welded joints[1,2]
Metallographic investigations showed that the weld metal of type-A samples was completely austenitic (Figure 1) due to existence of Ni entering into the weld metal as an austenite-promoting element; weld metal in type-B samples had duplex ferritic-austenitic microstructure (Figure 2)
It was concluded that the Cr/Ni = 2.00 ratio was sufficient for weld metal to solidify as ferritic-austenitic (FA type) which resulted skeletal morphology of δ-ferrite
Summary
According to the fact that every part of a process system operates at a specific condition, different structural alloys such as stainless steels, low-alloy and carbon steels due to their special properties are used in the design; resultant in dissimilar metal welded joints[1,2]. Dissimilar metal welding of stainless steels to carbon or low alloy steels has a wide application in industry. These dissimilar metal joints are widely used in pressure vessels, boilers, heat exchangers of power generation industry and petrochemical plants and oil and gas industry; they have a number of challenges such as solidification cracking, hydrogen cracking, and formation of brittle phases that may cause the failure of components before the expected design life[8,9,10,11].
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
