The Influence of the Post-Weld Heat Treatment on the Microstructure of Inconel 625/Carbon Steel Bimetal Joint Obtained by Explosive Welding

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).

The influence of the post-weld heat treatment on the microstructure of Mangalloy – carbon steel clad-plate obtained by explosive welding

“…One of the most promising technologies, which combines low cost and excellent properties of the product, is the explosive welding technique [10][11][12]. In this process, the energy released during detonation of the high explosive is used to accelerate one metal plate into another, and as a result, the high-velocity collision of metal plates occurs, which allows us to form a metallic bond between them [11,13,14]. This technol-ogy allows producing a bimetallic clad-plate consisting of load-bearer, inexpensive material (e.g., carbon steel) and cladding material which provides a specific resistance for corrosion or wear [11].…”

“…This technol-ogy allows producing a bimetallic clad-plate consisting of load-bearer, inexpensive material (e.g., carbon steel) and cladding material which provides a specific resistance for corrosion or wear [11]. Explosive welding is widely used for the production of corrosionresistant equipment for the chemical industry (e.g., heat exchangers, pressure vessels) [10,13]. The important aspect of this process is a significant strain hardening in the bimetallic joint zone, which causes problems in the forming process of the clad-plate.…”

“…The important aspect of the explosive welding technique is knowledge about microstructure changes in the joint line during heat treatment. Depending on the properties of welded materials, there is a possibility of new phase formation (including intermetallic compounds) due to diffusion changes in the joint subjected to annealing process [13,15]. Significant plastic deformation in the joint area also can drastically reduce the amount of energy needed for heat-activated phenomena in welded materials, e.g., precipitation processes, recrystallization [13,[18][19][20].…”

Orbital TIG Welding of Titanium Tubes with Perforated Bottom Made of Titanium-Clad Steel

“…they are not connected with bulkheads). Technologies applied for the joining of tubes with perforated walls include welding, tube expanding, adhesive bonding or explosion welding [18][19][20][21][22].…”

Research on microstructure and mechanical properties of explosively welded stainless steel/commercially pure Ti plate

“…Often surface protection is realized by coatings, but due to different chemical composition and structure of the connected materials, sometimes joining process is impossible to carry out by conventional welding or bonding methods [1][2][3]. This problem can be solved by using an explosive welding method which is one of the most effective technical engineering processes among joining methods because is used to join a wide variety of similar or different metals like steel and titanium [4]. The main advantage of this process is a possibility to optimize the performance of the composite for high temperature, cryogenic, high strength, thermal or electrical conductivity, enhanced mechanical properties, corrosion resistance, or any other applications [5].…”