Welding Metallurgy of

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

The temperature distribution and cooling rate during the welding process have significant effects on the mechanical and metallurgical properties of a weldment. The change in microstructure,...

Three-dimensional finite element analysis to predict the different zones of microstructure in submerged arc welding

The submerged-arc welding of steels has been used since 1930. It is well known that the mechanical properties of steel weldments depend on the chemical compositions of electrodes and fluxes. The development of welding electrodes has been based on practical experiences. The study of welding deposits by means of physical metallurgy permitted to develop electrodes and fluxes for SAW process of steels. In contrast, the use of chemical and physical properties of fluxes for the development of welding process started in the 70 s. (Shah, 1986). Most of the works concerning with the fluxes for SAW process have been focused on its effect on microstructure and mechanical properties. Likewise, it has been interesting the study of the thermochemical and electrochemical reactions that occur at the welding pool which are very important for the transferring of metallic elements to the welds. In addition to the stated above, the electrode coverings is also a very important aspect to obtain weld metal with good mechanical properties. The covering materials are fluxes which are composed of different mineral chemical compounds such as, oxides, fluorides and carbonates (Singer & Singer, 1979). The firing and sintering process of fluxes during welding electrode processing promotes chemical reactions and phase transformations of these minerals. All these factors determine the valence or electric charge of the different elements which are deposited to the weld metal. All the oxides from flux may contribute to the dissolution process of different metallic elements and oxygen in the welding pool. These metallic elements can react with oxygen to form oxide inclusions which can serve as nucleation sites for the formation of some benefit phases such as acicular ferrite during the welding process (Davis & Bailey 1991). These events may improve the mechanical strength and ductility of weld metal. Thus, the purpose of this chapter is to show the effect of different fluxes on the chemical composition, microstructure and mechanical properties of weld metals by the submerged-arc welding procedure.

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Chemical and Physical Properties of Fluxes for SAW of Low-Carbon Steels

A review paper on effect of input welding process parameters on structure and properties of weld in submerged arc welding process

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 microstructure observed in the HAZ of a SA weld are spheroidized, partially transformed, grain-refined and grain-coarsened. 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 microsturctures, such as periodic pearlite, grain boundary ferrite with pearlite, and side plate with cementite along the side plate boundaries, are observed.

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

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

S. C. Saha

Papers

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

Study of submerged arc weld metal and heat-affected zone microstructures of a plain carbon steel