Influence of Structure of Hafnium Rods on Their Mechanical Properties, Corrosion and Radiation Resistances

Abstract

The results of studying the dependence of mechanical properties, corrosion and radiation resistances of hafnium rods on their structure are presented and reviewed in this paper. As observed, the rods in a fully recrystallized state with a finegrained structure possess optimal mechanical properties (high strength and ductility). Tensile strength of these rods at room temperature is of ≈575 MPa, percentage elongation is of 27-28%. Autoclave corrosion tests and anode polarization curves reveal that oxide films formed on hafnium samples in a fully recrystallized state are the most protective that is due to the low surface activity at the medium-metal interface. The corrosion rate of such hafnium rods at the initial period of oxidation (before the pre-transition period) is well described by the empirical power equation with the power coefficient of 0.242 ± 0.015. After the transition point (≈6000 h), the corrosion kinetics is described by a linear dependence with the oxidation rate of 3.12 ⋅ 10 −4 ± 2.07 ⋅ 10 −5 mg/(dm 2 ⋅ h). As shown, there is a correlation between the radiation growth of hafnium rods and their texture coefficient (Kearns's parameter) accor ding to the results of radiation tests carried out at the JSC 'SSC RIAR' (RF) as well as structural-textural studies of the same samples of hafnium rods in various structural states performed in this work. The results presented in this paper reveal that the coefficient of radiation growth linearly decreases with an increase of the Kearns's parameter to a value of 0.33. This indicates that hafnium rod samples with a more isotropic texture are less susceptible to radiation growth. The radiation growths differ, depending on the rods' structure. For rods with the same texture and different grain sizes, the samples with a fine-grained structure are less disposed to radiation growth. While Kearns's parameters are similar, the hafnium rods with a coarse-grained structure show a higher rate of radiation growth. The deformation *

Corrosion Properties Characterization of 06Cr18Ni10Ti, 08Cr18Ni10Ti Steels and 42CrNiMo Alloy under Conditions Simulating Primary Coolant of Pressurized Water Reactor

“…Based on the experience of performing similar works on the removal of corrosion products formed on samples during autoclave tests at 350°C and 16.5 MPa [26], a method was chosen that consists in the oxidation of the constituent oxide films in a KMnO4 solution and subsequent two-stage etching in the solution of EDTA (ethylenediaminetetraacetic acid) and H3Cit (citric acid) at temperatures in the range of 90-160°C. The micrograph of the 08Cr18Ni10Ti stainless-steel sample surface after autoclave testing for 3500 hours and after different stages of the oxide film removal process is given in Fig.…”