Abstract
Corrosion behaviours of mild steel were investigated by measurement of corrosion loss and stress corrosion cracking tests in methanol and its solutons containing formic acid. In methanol solution containing 0.5% formic acid, corrosion rate was maximum at the composition of approximately 98% methanol with 2% water and was minimum at 85 to 90% methanol with 10 to 15% of water. General corrosion and pitting corrosion were found in these solutions. Especially at temperatures of 40 to 50°C, many pits were observed. In methanol solution containing 0.05 and 0.5% formic acid, corrosion loss increased proportionally square root of immersion time. Addition of acid to 85 to 85.5% methanol with 14.5% water increased corrosion rate in the order of hydrochloric acid, formic acid and acetic acid. Sodium chloride addition to about 85% methanol solution containing 0.5% formic acid decreased corrosion rate in comparison with non addition. Stress corrosion cracking was not found before 140 hours in U-bend and 3 point bending tests in methanol solution containing formic acid.
