Corrosion Cracking Stainless Steel

Deterioration by clscc can lead to failures that have the potential to release stored energy and or hazardous substances.

Corrosion cracking stainless steel. Although no stainless steel grade is totally immune to chloride scc the relative resistance of stainless steels varies substantially. The most common environmental exposure condition responsible for scc of stainless steels is the presence of chlorides. Chloride stress corrosion cracking cl scc is a type of stress corrosion cracking scc and is one of the most well known forms of scc in the refining and chemical processing industries. The higher alloyed duplex stainless steel alloys ones with significant molybdenum and.

It is thought to start with chromium carbide deposits along grain boundaries that leave the metal open to corrosion. Areas where the oxide film can break down can also sometimes be the result of the way components are designed. It can be detrimental to austenitic stainless steels one of the main reasons these steels are not considered a cure all for corrosion problems. The duplex stainless steels were developed to exhibit comparable general corrosion resistance as 316ss but with reduced susceptibility to chloride stress corrosion cracking.

A precursor of stress corrosion cracking in chloride bearing environments is pitting corrosion occurring if the stainless steel is not sufficiently resistant to pitting. However with some chemicals notably acids the passive layer may be attacked uniformly depending on concentration and temperature and the metal loss is distributed over the entire surface of the steel. Stress corrosion cracking scc is the growth of crack formation in a corrosive environment. This mode of attack is termed stress corrosion cracking scc.

How to reduce the risk of stress corrosion cracking scc the risk of stress corrosion cracking scc can be minimized through plant and equipment design. Influence of alloy composition. The micrograph on the left x300 illustrates scc 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. Chloride stress corrosion cracking clscc is one the most common reasons why austenitic stainless steel pipework and vessels deteriorate in the chemical processing and petrochemical industries.

General corrosion normally stainless steel does not corrode uniformly as do ordinary carbon and alloy steels. It can lead to unexpected and sudden failure of normally ductile metal alloys subjected to a tensile stress especially at elevated temperature scc is highly chemically specific in that certain alloys are likely to undergo scc only when exposed to a small number of chemical environments.