中国低活化马氏体(CLAM)钢中富钽析出相的定性分析

Qualitative Analysis of Tantalum-rich Precipitate Phases in CLAM Steel

作为国际热核聚变实验堆包层的候选结构材料,CLAM钢具有优良的低活化、抗辐照肿胀及密度、比热、热导率、电阻率等物理性能。Ta是一种强碳化物形成元素,在钢中会形成Ta或富Ta的碳化物析出相。本文利用透射电子显微镜和能量色散谱仪对经980℃/30min正火和760℃/1h回火的中国低活化马氏体(CLAM)钢中的富钽析出相进行了定性分析。结果表明,在正火回火态的CLAM钢中存在以下两种富钽析出相:第一种为具有面心立方结构的富Ta的MC碳化物,尺寸较小,被认为有助于提高钢的高温蠕变性能;第二类为具有底心单斜结构的富Ta、Cr的M3(C,N)2碳氮化物,为首次在CLAM钢中发现,还需对这类析出相进行后续的深入研究以判断其对CLAM钢高温蠕变性能的影响。

As a candidate structural material for the blanket of international thermonuclear fusion experimental reactor,china low activation martensitic(CLAM)steel possesses fine characteristics in low activation,anti-irradiation swelling and other physical properties.Ta is a strong carbide forming element that can form Ta or Ta-rich carbides in steels.In the present study,Ta-rich precipitate phases in CLAM steel normalized at 980℃ for 30 min and tempered at 760℃ for 1 hwere qualitatively analyzed using transmission electron microscope and energy dispersive spectrometer.The results showed that two types of Ta-rich precipitate phases were present in the CLAM steel under normalized and tempered condition.The first type of Ta-rich precipitate phase was Ta-rich MC carbide with a face-centered cubic structure and relatively small size,and was deduced to improve the creep property of the steel at high temperature.The second type of Ta-rich precipitate phase was Ta-Cr-rich M3(C,N)2 carbonitride with a base-centered monoclinic structure,and was newly discovered in CLAM steel.Further studies on it are needed to determine its effect on high temperature creep property of CLAM steel.