| The stress corrosion cracking (SCC) characteristics of Zircaloy-4 sheet in iodine vapour environment were studied by three point bending method. SCC tests were conducted in an iodine vapour evironment with the concentration of 20 ㎎/㎤ at 300℃ in which the crack growth rate, fracture surface morphology and the effect of crystallorgraphic texture on the SCC susceptibility were determined. Specimens of as-received, furnace cooled and oil quenched from the β-phase region, respectively, were precracked in an iodine-methanol solution. The crack growth rate formula after Kreyns, da/dt=c.K＾n, were applicable to the test results. The vague of the exponent n ranged from 1.8 to 2.8. The varue of n decreased with the increase of the intensity of the normal basal pole texture, which suggested that the crystallographic texture influenced the SCC susceptibility. A mixed mode of transgranular and intergranular fracture was observed in the as-received specimen. Transgranular fracture mixed with cleavage was predominant in the heat-treated specimens. |
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