Formation of a Transition Zone Structure in Welded Joints between Dissimilar Steels

Abstract

The results of structural research of welded joints between pearlitic high-carbon steel and austenitic chrome-nickel steel obtained by contact welding are presented. As a result of the diffusion process and mechanical mixing of steels local alloyed areas surrounded by pearlitic colonies of high-carbon steel are formed in the transition zone of the weld. The transmission electron microscopy (TEM) has been employed. The formation of the austenitic-martensitic microstructure occurs due to reducing the amount of alloying elements in local areas as compared to the original austenitic chrome-nickel steel chemical composition. Both austenite and martensite have crystallographic characteristics with the following orientation relationships: [211] γ-Fe || [011] α-Fe; [11-1] γ-Fe || [-110] α-Fe. The presence of high-strength local regions in the transition area may lead to a significant reduction in сrack resistance of dissimilar steels welded joints.

Reliability Increase of Dissimilar Steel Welded Joints

“…According to the structural investigation results welds with inserts and without them were characterized by clear-distinguished boundaries between a weld joint and the base material as well as local zones in carbon steel and the martensitic interlayer in chromium-nickel steel. The results obtained were in good agreement with previously obtained results of initial joint investigations without low-carbon inserts [12,16]. However a width of these zones in joints with a barrier layer was significantly less (Fig.…”

“…Hadfield steel needs fast cooling while carbon steel should be cooled at a medium speed. Previous investigations [11][12][13][14] showed that high-strength martensitic structures could appear between carbon (rail) steel and chromium-nickel steel in welds. To avoid the formation of such structures a longtime heat treatment (annealing at 1000 °C during 3-5 hours) was suggested in [10].…”

Microstructural Evolution and Mechanical Performance of Two Joints of Medium-Mn Stainless Steel with Low- and High-Alloyed Steels

“…It was reported that the precipitation of carbide particles on the grain boundaries has pinning effects on the grain growth [ 54 , 55 , 56 ]. Therefore, the precipitated carbides in the TZ work as obstacles for the movement of the grain boundaries, which hinders the coarsening of the grains size at the TZ and works as heterogeneous nucleation sites, which enhances the formation of fine equiaxed structures in the TZ; therefore, the size of the grains at the TZ was finer than the grains which exist at the FB and CGHAZ, which is similar to the results presented in the literature [ 52 , 57 , 58 ].…”