Effect of iodine partial pressure on the iodine stress corrosion cracking behaviors of Zr-Sn-Nb alloy using the ring tensile test

In order to evaluate the effect of iodine partial pressure on the iodine stress corrosion cracking (I-SCC) behaviors of a Zr-Sn-Nb alloy, ring tensile tests were conducted at 350 °C and in atmosphere without iodine and with iodine partial pressure of 10 2 , 10 3 , and 10 4 Pa, respectively. Results show that the maximum load, fracture displacement, tensile strength, and fracture energy of the Zr-Sn-Nb specimens decrease monotonically with the increase of iodine partial pressure. The fracture morphology of specimen with 10 2 Pa iodine exhibits two different fracture regions. One is the mixture form of ductile and brittle fracture, and the other is only ductile fracture. For the specimen with 10 3 Pa, stair-shaped fracture surface is formed as a result of the alternative propagation of transgranular cracks and intergranular cracks. The critical iodine partial pressure of the Zr-Sn-Nb alloys is lower than 10 2 Pa under the present conditions.