Study of Submerged Arc Weld Metal and Heat-Affected Zone Microstructures of a Plain Carbon Steel

Abstract

The nature of microstructures in the subzones of the HAZ greatly influence weld metal toughness and strength BY A. JOARDER, S. C. SAHA AND A. K. GHOSE ABSTRACT. A detailed study on the microstructure of submerged arc (SA) weld metal and the heat-affected zone of a 1.2-cm (0.5-in.) thick plain carbon steel plate was carried out using transmission electron microscopy. The various subzone microstructures observed in the HAZ of a SA weld are spheroidized, partially transformed, grain-refined and graincoarsened. The grain-coarsened area exhibits predominantly Widmanstatten ferrite with pearlite, while the other subzones of HAZ reveal polygonal ferrite and pearlite. Depending on the number, size and distribution of inclusions, the weld metal microstructure varies. With a larger number of inclusions, grain boundary ferrite and, in absence of inclusion, either side plate with pearlite or cementite along the boundaries of side plates are observed. It is noticed that a limited number of larger size inclusions favor the formation of acicular ferrite. Because of the prevalence of varying cooling rates in weld metal, a wide range of microstructures, such as periodic pearlite, grain boundary ferrite with pearlite, and side plate with cementite along the side plate boundaries, are observed.

Influence of the chemical composition of flux on the microstructure and tensile properties of submerged-arc welds

“…The mechanical properties of welds are determined by the microstructure developed during the submerged-arc welding process [1]. It was suggested that the acicular ferrite provided a good toughness and tensile strength to the welds because its fine size has a higher resistance to the crack propagation [2].…”

Microstructure and wear property of Fe–Mn–Cr–Mo–V alloy cladding by submerged arc welding

“…The available research papers are focused on three areas: (1) microstructures and properties of bead and HAZ [1][2][3][4][5][6][7]; (2) bead characteristics in function of process variables [5,[8][9][10][11]; (3) gas/metal/slag reactions in welding process [12][13][14].…”

Microstructure and microhardness of flux-cored arc-welded joints for boiler quality steel

“…Austenite grains decompose into nonuniform distribution of small ferrite and pearlite grains during cooling due to limited diffusion time available for carbon. It is observed that the grain-refined area exhibits extremely small ferrite grains, clearly indicating that very fine polygonal ferrite and pearlite are formed due to the heating and cooling cycles of the FCAW process [18,19]. Figure 2, representing the grain-coarsened HAZ area, exhibits freshly formed martensite structure.…”