Integrity - Reliability - Safety

Sunday, January 20, 2008

Corrosion Morphology

1. Illustrative Corrosion Morphology (ASM)



2. Intergranular Corrosion,Sensitized 304 stainless steel exhibiting intergranular attack, 100×(ASM)



3. View of intergranular stress corrosion cracking (IGSCC) in an Inconel heat exchanger tube. 500X (MTi)



4. Caustic SCC in the HAZ of a type 316L stainless steel NaOH reactor vessel. Cracks are branching and intergranular (ASM)



5. Chloride stress corrosion cracking in a 316 stainless steel chemical processing piping system. Chloride stress corrosion cracking in austenitic stainless steel is characterized by the multi-branched "lightning bolt" transgranular crack pattern, Mag. 300X (MTi)



6. Transgranular SCC 304 Stainless Steel Base - 308 Stainless Steel Weld in aqueous chloride at 95C (ASM)



7. Pitting 316 stainless steel tubes, with downward propagation (ASM)



8. Pitting API 5LX-52 at Carlsbad PIpeline Explosion New Mexico US August 2000 (NTSB)



9. Metal Dusting at CCR platformer unit 9Cr Fe-Ni-Cr alloy tube (EFC)



Macrosocopic view



Partially molten segment

10. Hydrogen Embrittlement, 431 Stainless Steel Mushroom Head Closure (ASM)





Microscopic view showing transgranular cleavage of hydrogen embrittlement

11. Mercury Induced embrittlement in Al-alloy piping(a) Weld cap with through-wall branched cracking. (b) Cross section at the through-wall crack location. (c) Branched, intergranular cracking at a crack tip. 27× (ASM)



Failed Nozzle in Heat Exchanger Explosion Longford Australia 1998



12. Crevice Corrosion of Austenitic stainless steel tube that was corroded where a fabric bag was taped to it (ASM)



13. Tubercles associated with pitting in galvanized steel pipe from water (Little)



14. Biodeposited manganese oxide on 316L stainless steel (UNS S31603) exposed to fresh water (Little)





15. High Temperature Hydrogen Attack, C-0.5Mo, Desulphurization Reactor (NDE)



Microstructure of C-0.5Mo showing methane gas voids on grain boundaries (Idemitsu)



Increases of gaseous methane pressure in the voids results in micro-fissure formation (Idemitsu)



Macroscopic view of HTHA embrittlement (CSB)

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