Investigation of Welding Heat Input Influences on the Characteristics of Welded Joint of Storage Tank Wall Using Multiple Passes.

The correlation of welding input heat and microstructure and its impacts on multi-pass mechanical properties in storage tanks alloy steel plate of thickness 6mm using multiple passes SMAW was investigated experimentally and using SOLIDWORKS and ANSYS thermal and Mechanical Simulator. The heat-affected zone (HAZ) dimension was calculated, and the deformation in each pass was also calculated. Optical microscopy was used to characterize the weld metal microstructure effects on joint mechanical properties, the effects of the three pass sequences in deformation, and the resulting alterations in weld metal microstructure. In addition, the impact of this alteration in corrosion resistance characteristics was investigated, and steel samples were simulated. The investigation results illustrated increasing the weldment deformation with increasing heat inputs in the three-pass sequence. The welding joint microstructure shows a big difference in M-A (martensite-austenite) phase formation between the first, second, and third pass microstructure. In addition, the microstructure examinations showed the formation of AF (acicular ferrite) in the third pass, with a higher percentage in the second and first pass. This research demonstrated scientific information about the expected deformation of each pass from the three welding joints, the alteration in microstructures, and the corrosion resistance of the weldment according to the alteration with welding heat input. [ABSTRACT FROM AUTHOR]