Analysis of Heat Treatment on Pitting Resistance of 14Cr1MoR+904L Steel

ASTM G48 A and ASTM 262 B methods were employed to analyze the pitting and intergranular corrosion performance of 14Cr1MoR(H) + 904 L used for pressure vessel after 904 L experiencing different heat treatment. The results showed that the microstructure of original 904 L was twin austenitic,whose pitting and intergranular corrosion rates were 0.008 mm/a and 0.826 mm/a; the microstructure and pitting corrosion speed of 904L had no significant changes after experiencing explosive welding + 675℃/3h heat treatment and adding to 690℃/4h heat treatment for 14 Cr1MoR(H) + 904 L shell,meanwhile,the intergranular corrosion rate gradually increased. After the head experiencing the heat treatment of 950℃/1.0h + 920℃/1.5h + 690℃/6.0 h,the corrosion resistance declined seriously as the precipitation organization occured around prior austenite boundaries.