Low temperature thermal aging of austenitic stainless steel welds: Kinetics and effects on mechanical properties
Low temperature thermal aging of austenitic stainless steel welds: Kinetics and effects on mechanical properties
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DOI：
10.1016/j.msea.2011.11.055
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发表时间：
2012-02-01
期刊：
影响因子：
6.4
通讯作者：
Chakravartty, J. K.
中科院分区：
文献类型：
--
作者：
Chandra, K.;Kain, Vivekanand;Chakravartty, J. K.
轻水反应堆中使用的部件中的奥氏体不锈钢焊缝在长使用寿命后在约300摄氏度的反应堆操作温度下容易发生热老化脆化。在这项研究中，根据在335、365和400摄氏度下老化20，000小时后力学性能和显微组织的变化，研究了含10%铁素体的304 L和316L型不锈钢焊缝的低温时效脆化。时效后观察到铁素体中的调幅分解和G相析出，导致材料脆化。在对比的拉伸性能的小的影响，冲击韧性显着降低时效后。夏比冲击试验结果表明，时效后试样的上、下架能降低，韧脆转变温度升高。铁素体相的显微硬度大幅度增加，而奥氏体硬度没有变化。在相同的时效条件下，316L焊缝的脆化程度高于304 L焊缝。基于Arrhenius关系建立了时效脆化动力学模型。304 L焊缝在335-400 ℃温度范围内的激活能恒定，而316L焊缝在每个温度范围内的激活能值不同。(C)2011 Elsevier B. V.保留所有权利。
Austenitic stainless steel welds in components used in light water reactors are susceptible to thermal aging embrittlement at reactor operating temperature of around 300 degrees C after a long service life. In this study, low temperature aging embrittlement of types 304L and 316L stainless steel welds with 10% ferrite was investigated on the basis of changes in mechanical properties and microstructure after aging up to 20,000h at 335, 365 and 400 degrees C. Spinodal decomposition and G-phase precipitation in the ferrite was observed after aging which lead to embrittlement in the material. In contrast to the small effect on tensile properties, the impact toughness was significantly degraded after aging. Charpy impact test of the aged samples showed decrease in upper-shelf and lower-shelf energy and increase in ductile brittle transition temperature. Large increase in the microhardness of ferrite phase was observed with no change in austenite hardness. The embrittlement in 316L weld was higher compared to 304L weld for similar aging condition. The kinetics of aging embrittlement was established based on Arrhenius relationship. A constant activation energy was determined for 304L weld in the temperature range 335-400 degrees C, however, 316L weld showed different activation energy values in each temperature range. (C) 2011 Elsevier B.V. All rights reserved.