Abstract
The effect of grain boundary microstructures on sulfur segregation-induced intergranular embrittlement in polycrystalline nickel was investigated in comparison with the results for specimens with ultrafine-grained structure. The fraction of low-energy (low-Σ) boundaries was controlled by thermomechanical processing. A high fraction of low-Σ boundaries (59 %) was obtained for the specimen subjected to 5 % cold rolling and subsequent annealing at 1273 K for 3.6 ks. On the other hand, the specimen which subjected to 30 % cold rolling and annealing at 1325 K for 3.6 ks, possessed a lower fraction of low-Σ boundaries (39 %). The bending strength in specimen with lower fraction of low-Σ boundaries were considerably scattered, while the specimen with higher fraction of low-Σ boundaries shows almost constant bending strength. It is evidenced that the approach to grain boundary engineering is applicable to controlling sulfur segregation-induced embrittlement in polycrystalline nickel.
