Stress corrosion cracking of bainite 0.3C‐1Cr‐1Mn‐1Si‐1Ni type steel in acid rain simulated solution

The effect of carbon content, heat treatment and surface treatment of high strength aircraft 0.3C‐1Cr‐1Mn‐1Si‐1Ni type steel on susceptibility to pitting corrosion, on hydrogen transport and on hydrogen embrittlement has been studied in acid rain simulated solution. Under open circuit conditions, susceptibility to stress corrosion cracking is associated with susceptibility to pitting corrosion and decreases with decreasing carbon content and at application of shot peening. Susceptibility to hydrogen embrittlement governed by hydrogen trapping is promoted by carbon segregation at boundaries of bainite laths and parent austenite grains. Decrease in the carbon content caused the decrease in hydrogen trapping resulting in increasing resistance to hydrogen embrittlement. Shot peening increased the trapping efficiency within the deformed layer, but the presence of the shot peened layer decreased the hydrogen flux entering the core and thus decreased the susceptibility of the core to hydrogen embrittlement. The shot peened low carbon steel, exhibiting mechanical properties required by the appropriate Standard and high resistance to stress corrosion cracking may be considered to replace the standard 0.3C‐1Cr‐1Mn‐1Si‐1Ni steel for the aircraft parts.