• EC • Season Cracking • Caustic Embrittlement • SCC • SSC • LME • HB-HE-HIC • Fatigue • Erosion • Fretting • Stray Current • Index

Different Types of Corrosion
- Recognition, Mechanisms & Prevention

Caustic Embrittlement

Recognition

What is caustic embtittlement?

"Caustic embrittlement" was first used to describe the cracking of riveted mild steel boiler plates due to local deposition of concentrated hydroxide at temperatures of 200 to 250^oC (400 to 480^oF). It was later known as "stress corrosion cracking" which was in turn replaced by "environmental cracking".

What causes caustic embrittlement? Caustic embrittlement results from the conjoint action of three components: (1) a susceptible material (carbon steel); (2) a specific chemical species (concentrated hydroxide) and (3) tensile stress (around the riveted holes).

Caustic soda (NaOH) was added in small amounts to boiler water to prevent scaling but the presence of caustics (alkalis), usually concentrated in crevices around rivet heads and at hot spots, combined with the considerable fabrication stresses around rivet holes to caused cracking of the steel boiler shells and tube plates.

• Control of stress level (residual or load) and hardness.
• Avoid alkalis.
• Use of materials known not to crack in the specified environment.
• Control temperature and or potential

Corrosion and Its Prevention (5-day module)
Corrosion and Its Prevention (2-day module)
Corrosion, Metallurgy, Failure Analysis and Prevention (3 days)
Marine Corrosion, Causes and Prevention (2 days)
Materials Selection and Corrosion (2 days)
Stainless Steels and Alloys: Why They Resist Corrosion and How They Fail (2 days)

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