Monitoring Sub-Critical Crack Growth due to Stress Corrosion or Hydrogen Embrittlement by Acoustic Emission

Abstract

Acoustic emission ring-down counting has been used to monitor sub-critical crack growth by stress corrosion of mild steel in disodium hydrogen phosphate, -brass in sodium nitrite and magnesium–7% aluminium in potassium chromate/sodium chloride mixtures, and by hydrogen embrittlement in mild steel and a 7179 T651 aluminium alloy. The level of acoustic emission activity varies widely between different alloy/environment systems and is dependent upon microstructure, fracture path and crack growth rate. The practical significance of the results is discussed.