Experimental Study and Finite Element Computation of the Single Crystal Behavior of Zirconium

The mechanical behaviour of zirconium alloys, used as cladding of nuclear fuel for water reactor, is well known. However there is yet no single crystal constitutive law for zirconium.In order to determine the single crystal behaviour, a zirconium alloy (containing 100 ppm oxygen) with millimetre grains is used. Tensile specimens are machined to obtain only one grain, well orientated for prismatic slip, in the gauge length. The specimens are covered by a speckled paint. During the tests, the in plane deformation is monitored. Thanks to digital image correlation, the strain field tensor is deduced and resolved along the slip systems giving the shear strain on prismatic planes. The single crystal behaviour for prismatic slip is deduced. Strain rates jumps and relaxation tests are also conducted with the same method to measure the activation volume. Finite elements computations of the full specimens are then performed using the fitted constitutive law.