摘要
开展了核电站主管道316LN焊缝在325℃、365℃和400℃下15000h的加速热老化试验。通过TEM和HRTEM研究了不同热老化温度下焊缝的微观组织演变，采用纳米力学探针对热老化后焊缝中铁素体相和奥氏体相的显微硬度进行了测定，结果表明：经325℃、365℃热老化15000h后焊缝中的铁素体都发生了调幅分解，而在400℃下热老化1000h后焊缝铁素体已经发生了调幅分解和析出了G相；长期热老化导致铁素体相塑形变形能力不断下降，显微硬度快速增加，而奥氏体相的显微硬度未发生改变；以铁素体显微硬度值作为热老化程度指标，利用Arrhenius方程得出了316LN焊缝在325～400℃内的热老化激活能约为93．1kJ／mol。
t The accelerated thermal aging experiments of nuclear primary pipe material 316LN stainless steel weld were performed at 325 ℃ ,365 ℃ and 400℃ for 15000 h. TEM and HRTEM were utilized to ohserve the microstructure. A nanodndenter was used to study the changes of the microhardness. The results indicated that spinodal decomposition and G-phase precipitation in the ferrite was observed after aging which lead to embrittlement in the material. Large increase in the microhardness of ferrite phase was observed with no change in austenite hardness. Taking the microhardness as the standard of thermal aging embrittlement, the thermal aging activation energy was determined for 316LN weld in the temperature range 325--400 ℃ based on Arrhenius relationship.
基金
国家科技重大专项项目(2011ZX06004-002)
关键词
316LN焊缝
热老化
调幅分解
显微硬度
316LN weld, thermal aging, spinodal decomposition, microhardness
