Welded Elements Research Articles

Corrosion cracking of Cr−Ni−Mo−Cu steels in sulphuric acid solutions

1. Cr−Ni−Mo−Cu steels Kh18N28M3D3, Kh23N23M3D3, Kh23N28M3D3T and OKh23N28M3D3T recommended for use in sulphuric acid are prone to intercrystalline corrosion. Most susceptible to this corrosion are steel Kh18N28M3D3 and steel Kh23N23M3D3, they cannot be used for welded elements operating in sulphuric acid surroundings. 2. Welded joints of steel Kh23N28M3D3T with less than 0.06% C are immune to intercrystalline corrosion. This steel is recommended for welded elements operating in sulphuric acid solutions. 3. When the steels under study contained residual stresses, they suffered from transcrystalline corrosion cracking in 20, 30, 40 and 50 weight-% solutions at 80° C and at boiling temperature. Heating of steel Kh23N28M3D3T at 950°C followed by air cooling reduced its susceptibility to corrosion cracking under stress.