METHOD FOR PREVENTING INTERGRANULAR DAMAGE OF NI-BASED ALLOY

摘要

PURPOSE:To prevent the generation of intergranular damage in an Ni-based alloy by adding a specified amt. of a cyclic amine to a soln., and adding a specified amt. of gaseous hydrogen to a vapor phase in the high-temp. deaerated alkaline soln. being in contact with the vapor phase with which the Ni-based alloy is brought into contact. CONSTITUTION:From 0.1ppm to 1% cyclic amine, based on the weight of the soln., is added into the high-temp. deaerated alkaline soln. being in contact with the vapor phase with which the Ni-based alloy is brought into contact, and 3X10-5-1X10-1 gaseous hydrogen, based on the total pressure of 1atm (absolute pressure) of the vapor phase, is added. Homopholine, cyclohexylamine, benzotriazole, etc., are used as the cyclic amine. By this method, the generation of intergranular damage in the Ni-based alloy to be used for the tubes of a heat exchanger, etc., is prevented.