Abstract
Inconel 625 and steel P355NH were bonded by explosive welding in this study. Explosively welded bimetal clad-plate was subjected to the two separated post-weld heat treatment processes: stress relief annealing (at 620 °C for 90 min) and normalizing (at 910 °C for 30 min). Effect of heat treatments on the microstructure of the joint has been evaluated using light and scanning electron microscopy, EDS analysis techniques, and microhardness tests, respectively. It has been stated that stress relief annealing leads to partial recrystallization of steel P355NH microstructure in the joint zone. At the same time, normalizing caused not only the recrystallization of both materials, but also the formation of a diffusion zone and precipitates in Inconel 625. The precipitates in Inconel 625 have been identified as two types of carbides: chromium-rich M23C6 and molybdenum-rich M6C. It has been reported that diffusion of alloying elements into steel P355NH takes place along grain boundaries with additional formation of voids. Scanning transmission electron microscope observation of the grain microstructure in the diffusion zone shows that this area consists of equiaxed grains (at the side of Inconel 625 alloy) and columnar grains (at the side of steel P355NH).
Highlights
Corrosive wear is a significant problem for the utilization of components of equipment operating in an aggressive environment, such as reactors, tanks, heat exchangers, and pipelines in the chemical industry and geothermal power plants [1,2]
This paper investigates steel P355NH cladded with Inconel 625 as bimetallic material of the above type
Stress relief annealing has a lowest impact on grainy microstructure and leads only to partial recrystallization of annealing has a lowest impact on grainy microstructure and leads only to partial recrystallization of steel P355NH grains in the joint zone
Summary
Corrosive wear is a significant problem for the utilization of components of equipment operating in an aggressive environment, such as reactors, tanks, heat exchangers, and pipelines in the chemical industry and geothermal power plants [1,2]. The alloys which can provide a specified resistant against corrosion in the aggressive environment are expensive. An approach worth considering is the use of relatively inexpensive material (e.g., non-alloy steel) and cladding it with layer of corrosion resistant alloy, such as stainless steel or nickel alloy providing potentiality of operating in the aggressive environment. This solution allows to reduce the material cost of industry equipment significantly depending on used manufacturing technique [3,4,5]. As an example of such bimetal clad plate Inconel/steel system can be given, in which steel is a load-bearing component while Inconel provides resistance to an aggressive environment
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