Corrosion behavior and susceptibility to stress corrosion cracking of leaded and lead-free brasses in simulated drinking water

Duplex α + β’ brasses are widely used in drinking water distribution systems for tube fittings, valves, and ancillaries because they are low cost, easy to fabricate, and exhibit high mechanical strength. However, depending on application conditions and alloy composition, they may undergo dealloying and stress corrosion cracking. In this research, three different brass types, two leaded (CW617N and CW602N) alloys and one lead-free brass (CW724R), were investigated to assess their corrosion behavior and susceptibility to stress corrosion cracking (SCC) in simulated drinking water (SDW) solutions containing different chloride concentrations, compatible with drinking water composition requirements according to Moroccan standard NM 03.7.001. The corrosion behavior was assessed by electrochemical tests such as polarization curve recording and electrochemical impedance spectroscopy (EIS) monitoring, coupled to SEM-EDS surface observations. The susceptibility to SCC was investigated by slow strain rate tests (SSRT). The tests showed that corrosion was mainly under diffusion control and chlorides slightly accelerated corrosion rates. All alloys, and particularly CW617N, were affected by SCC under the testing conditions adopted and in general the SCC susceptibility increased at increasing chloride concentration.