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Article Type

Original Study

Abstract

The aim of this study is to investigate the corrosion behavior and mechanical properties of welded steel exposed to gases emitted from crude oil reservoirs. In this study, two types of nanoparticles were used as fillers during welding to improve corrosion and mechanical properties. TiO2 and SiO2 nanoparticles were mixed with soldering oil in four mass concentrations of 0, 1, 2.5 and 5% by ultrasonic bath method and used as filler during the welding process. In order to prepare the samples, plain carbon steel with a thickness of 3 mm was used and they were welded together by electric arc welding. Then, characteristics such as mass loss percentage, optical microscope and SEM imaging, polarization corrosion test and tensile and bending test were performed on the samples. Also, this test was used as finite element modeling by Abaqus software. The results of microstructure examination showed that in the weld button, the grain size was smaller due to recrystallization and the grains grew in the longitudinal direction, but the grain size in the base metal area was uniform. The results of the weight loss percentage study showed that the effect of TiO2 nanoparticles in preventing mass loss of the samples was better and the lowest mass loss was observed at a mass percentage of 2.5%. Overall, the results of this study showed that for the use of 2.5% TiO2 nanoparticles as a filler material during welding of plain carbon steel, the corrosion resistance, tensile and flexural strength of the samples improved by 97.38%, 16.67% and 24.19%. The results of the tensile and bending tests showed that the addition of TiO2 nanoparticles during the welding process increased the maximum flexural and tensile strength of the welded samples, so that for the sample with 2.5% nanoparticles, the maximum flexural and tensile strength increased by 10.74% and 9.93%, respectively. Comparison of numerical and experimental modeling results showed that the error of numerical modeling by finite element method in measuring tensile and flexural strength was 13.19% and 9.07%, respectively.

Keywords

Nanofiller, Welding, Microstructure, Mechanical properties, Corrosion

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