Characterization of microstructure and local deformation in 316NG weld heat-affected zone and stress corrosion cracking in high temperature water

Microstructure and local deformation in 316NG weld heat-affected zones were measured by electron-back scattering diffraction and hardness measurements. With increasing the distance from the fusion line, kernel average misorientation decreases and the fraction of Σ3 boundaries increases. Stress corrosion cracking growth rates in high temperature water were measured at different locations in the heat-affected zones that correspond to different levels of strain-hardening represented by kernel average misorientation and hardness distribution. Intergranular cracking along random boundaries as well as extensive intergranular crack branching is observed in the heat-affected zone near the weld fusion line.

Research highlights
► Away from the fusion line, kernel average misorientation and hardness decrease.
► Away from the fusion line, the fraction of Σ3 boundaries increases.
► Crack growth in high temperature water correlates to kernel average misorientation and hardness.
► SCC along random boundaries as well as extensive intergranular branching near the fusion line.