1. General Susceptibility to Chloride‑Induced SCC
Inconel 600 is susceptible to stress corrosion cracking in chloride environments, particularly under the following conditions:
Presence of dissolved chlorides (Cl⁻)
Elevated temperatures (typically above 100°C, but risk increases significantly above 200°C)
Tensile stress (residual or applied)
Oxidizing conditions
Under these combined factors, Inconel 600 can experience transgranular stress corrosion cracking (TGSCC) or intergranular stress corrosion cracking (IGSCC), depending on temperature, chloride concentration, and material condition.
2. Key Mechanisms of Chloride SCC in Inconel 600
(1) Chloride Adsorption and Film Breakdown
Chloride ions are highly aggressive and can:
Adsorb onto the protective Cr₂O₃ surface film
Disrupt the oxide layer, creating weak points
Promote localized dissolution and pit formation
Pits act as stress concentrators and can initiate SCC cracks.
(2) Hydrogen Involvement (Possible Mechanism)
In some chloride environments, hydrogen evolution can occur, leading to:
Hydrogen absorption into the metal
Reduction in ductility
Promotion of cracking (similar to hydrogen embrittlement)
This mechanism is more pronounced in acidic chloride solutions.
(3) Intergranular Attack (IGA) Leading to IGSCC
At temperatures between 300–700°C, Inconel 600 may undergo sensitization, causing:
Chromium depletion at grain boundaries
Formation of chromium carbides (Cr₂₃C₆)
Reduced corrosion resistance along grain boundaries
In chloride‑containing environments, this can lead to intergranular stress corrosion cracking (IGSCC).
