N36锆合金包壳管的高温蠕变行为

High Temperature Creep Behavior of N36 Zirconium Alloy Cladding Tubes

摘要:

研究了N36锆合金包壳管在温度为593~723 K、应力为60~160 MPa条件下的拉伸蠕变行为。结果表明，本试验条件下N36锆合金管材存在不同的蠕变变形机制。593~673K下低应力范围内，蠕变应力因子n约为3，蠕变表观激活能Qapp≈150 kJ·mol-1，蠕变变形受位错的粘滞性滑移过程控制；高应力范围内蠕变应力因子n为5~6，蠕变激活能Qapp≈170 kJ·mol-1，遵循典型的5次幂律蠕变规律，蠕变变形受位错攀移过程控制。在723 K时，高应力范围内发生幂律失效。N36锆合金包壳管表现为典型的Class A型合金蠕变特征，表现出与Zircaloy合金不同的蠕变规律。

Abstract:

High temperature tensile creep behavior of N36 zirconium alloy cladding tubes in the temperature range from 593 K to 723 K and the stress range from 60 MPa to 160 MPa was investigated. The results show that there are three distinct rate-controlled creep mechanisms for N36 zirconium alloy cladding tubes. In the temperature range from 593 K to 673 K the stress exponent n is ~3 and creep activation Q≈150 kJ·mol-1 is found in the low applied stress region, which means the dominant process is viscous-glide-controlled. But in the high applied stress region the stress exponent n is 5~6 and the creep activation Q≈170 kJ·mol-1 is found, which obeys the typical five power law creep mechanism controlled by the climb of edge dislocations. At 723 K and with high applied stress the power law breakdown appears and the exact mechanism is not clear by now. In the test condition N36 zirconium alloy cladding tubes exhibit a type of creep behavior similar to that noted in class-I(A) alloys, which is very different from zircaloy.