Role of M23C6 carbide precipitation and phosphorus grain boundary segregation in intergranular fracture and corrosion of 18Cr-12Ni austenitic stainless steel

The effects of intergranular precipitation (size of precipitates) and phosphorus grain boundary segregation on fracture and corrosion behaviours of the 18Cr-12Ni steel were investigated. In the investigation, techniques of light microscopy, SEM, TEM, AES, EDX, electron diffraction, and the Huey test were used. A good correlation was found between the average size of intergranular particles and the portion of intergranular fracture for samples impact loaded at 173 K. The equilibrium values of phosphorus grain boundary concentration showed the close correlation with the values of weight loss (penetration depth) measured during the Huey test.