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Investigators examined microstructural changes together with strength and corrosion resistance properties in alloy steel joints created by Gas Metal Arc Welding (GMAW) and Shielded Metal Arc Welding (SMAW). The research analyzed the effects of welding heat input on microstructure development and its effect on the corrosion performance. The research examined ASTM A516 Grade 70 steel welds' corrosion behavior welded using GMAW and SMAW after immersing them in ferric chloride solution for 81 hours. The GMAW welding process generated a narrower Heat Affected Zone (HAZ), resulting in an average corrosion rate of 8.31 mm/year at 81 hours; SMAW produced a slightly elevated final corrosion rate of 8.73 mm/year. GMAW fusion zone displayed fine dendritic features, different from the SMAW fusion zone, which contained coarser grain patterns. SMAW heat-affected zone exceeded GMAW's zone by 5 mm, reaching up to 19 mm, which led SMAW joints to increased corrosion vulnerability. GMAW joints' mechanical properties yielded 588 MPa tensile strength measurement, which corresponded to 5.1% reduction from the base metal, slightly higher than SMAW joints at 578 MPa and 5.2% reduction from base metal strength values. Toughness measured using Charpy tests on GMAW samples showed higher results at 72 J compared to 65 J obtained from SMAW. The weight loss analysis showed GMAW initial corrosion speed 60.12 mg decline at 5 hours before achieving 3.53 g stability at 81 hours. SMAW corrosion development was slower since the material lost 30.19 mg after the initial 5 hours before reaching 3.99 g after 81 hours. Results show GMAW produces better general corrosion resistance and mechanical properties than SMAW joints.
