Axial Tensile Creep Behavior at High Temperature ofSZA-6 Zirconium Alloy for Cladding Tubes

Axial tensile creep tests were conducted on SZA-6 zirconium alloy for cladding tubes under stresses of 117, 137, 157 MPa and temperatures of 633, 658, 683 K. The axial tensile creep behavior of the alloy was studied. The creep control mechanism was analyzed through creep stress exponent and creep activation energy. The results show that the steady creep rate of SZA-6 zirconium alloy ranged from 0.34×10^-8 s^-1 to 9.77×10^-8 s^-1 under different test conditions. The steady creep rate increased with increasing test temperature or stress. The creep stress exponent increased from 5.66 to 8.69 as the stress increased from 117 MPa to 157 MPa at 658 K. The creep activation energy was 181.76 kJ·mol^-1 under stress of 117 MPa. The creep control mechanism under stress of 117 MPa was mainly grain boundary slipping, which was not affected by test temperatures; as the stress increased to 137 MPa and the test temperature was 658 K, the mechanism of dislocation climbing played a dominant role in the creep behavior.