包壳管用SZA-6锆合金的高温单轴拉伸蠕变行为

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

在应力117,137,157 MPa及温度633,658,683 K条件下对包壳管用SZA-6锆合金进行单轴拉伸蠕变试验,研究了该合金的单轴拉伸蠕变行为,并通过蠕变应力指数和蠕变激活能分析其蠕变控制机制。结果表明:SZA-6锆合金在不同试验条件下的稳态蠕变速率在0.34×10^(-8)~9.77×10^(-8)s^(-1)范围,随着试验温度的升高或应力的增大,稳态蠕变速率增大;在658 K温度下,当应力由117 MPa增大至157 MPa时,蠕变应力指数由5.66增大至8.69;在117 MPa应力下的蠕变激活能为181.76 kJ·mol^(-1)。117 MPa应力下的蠕变控制机制以晶界滑移为主,不受试验温度影响;当应力增大至137 MPa、试验温度为658 K时,位错攀移机制对蠕变行为起主导作用。

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.