The environment-induced cracking of as-annealed Ni3(Si,Ti) and Ni3(Si,Ti) with 2Mo in sodium chloride solutions

Abstract

Background

The environment-induced cracking (EIC) of as-annealed Ni3(Si,Ti) and Ni3(Si,Ti) with 2Mo has been researched as functions of applied stress, chloride ion concentration, test temperature, and pH.

Methods

The investigation of EIC was carried out by applying a constant method in NaCl solutions.

Results

The EIC susceptibility of both intermetallic compounds increased with increasing test temperature and Cl− ion concentration and increased with decreasing pH. The fracture surface morphologies of Ni3(Si,Ti) was intergranular while Ni3(Si,Ti) with 2Mo was a mixture of intergranular and transgranular, and the relationship between log t f (time to failure) and log l ss (steady-state elongation rate) became the identical straight line irrespective of applied stress, chloride ion concentration, test temperature, and pH, which means that l ss becomes a relevant parameter for predicting t f. The EIC susceptibility of Ni3(Si,Ti) with 2Mo was lower than that of Ni3(Si,Ti), which showed the advantageous effect of Mo.

Conclusions

From the results acquired, EIC of both the compounds was indicated to take place by hydrogen embrittlement (HE).