Thermal aging effect on Z3CN20.09M Cast Duplex Stainless Steel
Thermal aging effect on Z3CN20.09M Cast Duplex Stainless Steel
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DOI：
10.1016/j.nucengdes.2009.06.009
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发表时间：
2009-11-01
影响因子：
1.7
通讯作者：
Ti, Wenxin
中科院分区：
文献类型：
--
作者：
Xue, Fei;Wang, Zhao-Xi;Ti, Wenxin
对在 400 摄氏度下老化长达 3000 小时的 Z3CN20.09M 铸造双相不锈钢 (CDSS) 进行了仪器冲击测试。该材料是从压水堆的主管上切割下来的，以研究加速热老化脆化对动态断裂性能的影响。仪器冲击试验的载荷-挠度曲线描述了载荷和断裂阶段，从中计算动态极限载荷水平和动态极限强度作为老化时间增加的函数。动态极限强度随老化时间的增加远高于静态极限强度。随着时效时间的增加，裂纹萌生能和裂纹扩展能均下降，与以最大载荷水平为裂纹萌生点的总冲击能分开。结果表明，断裂扩展能的降低趋势是冲击能降低的主要原因。随着时效时间的增加，反映裂纹扩展速度的卸载斜率增大，断口形态从浅韧窝的韧性断裂转变为铁素体基体中位错堆积引起的解理脆性断裂。具有细等轴晶组织的内壁力学性能明显优于具有粗柱状组织的外壁。 (C) 2009 Elsevier B.V. 保留所有权利。
Instrumented impact tests were performed on Z3CN20.09M Cast Duplex Stainless Steel (CDSS) aged at 400 degrees C for up to 3000h. The material was cut from the primary pipe of a PWR to investigate the accelerated thermal aging embrittlement effect on the dynamic fracture properties. The load-deflection curves from the instrumented impact tests described both the loading and the fracture stages, from which the dynamic ultimate loading level and the dynamic ultimate strengths were calculated as a function of increased aging time. The increase in the dynamic ultimate strengths with aging time is much higher than those for the static ultimate strengths. With the increment of the aging time, both the crack initiation energy and the crack propagation energy decrease, which are separated form the total impact energy taking the maximum loading level as the crack initiation point. it is shown that the reduction tendency of the fracture propagation energy is the predominant reason for the reduction of the impact energy. With the increment of the aging time, the unloading slopes reflecting the crack propagation speed increase and the fracture surface patterns change from ductile fracture with shallow dimples to cleavage brittle fracture caused by dislocations piling up in the ferrite matrix. Mechanical properties of inner wall with fine equi-axed grains are much better than those of the outer wall with coarse columnar structures. (C) 2009 Elsevier B.V. All rights reserved.