Abstract
A simple test method is proposed for reproducing stress corrosion cracking of pure copper in ammoniacal environment. A test tube of ammonia aqueous solution and C-ring specimens sampled from a pure copper tube were put in a 500mL polypropylene bottle for three weeks under room temperature. The pure copper tubes used in this work were high phosphorous deoxidized copper tube containing 0.028% P, low phosphorous deoxidized copper tube containing 0.007% P and oxygen-free copper tube without P. Tempers of these tubes were H, 1/2H and O defined in JIS H0500. Intergranular corrosion or intergranular cracking was occurred on the surface of P-deoxidized 1/2H and O copper tubes under gas-phase ammonia derived from 1 to 9% ammonia water, while intergranular corrosion was not observed in the oxygen-free copper and all H-tempered copper tubes. It was found that no stress corrosion cracking occurs in the pure copper tubes without phosphorous or with small crystal grains by work hardening.
