18Cr9Ni3CuNbN奥氏体耐热钢中富Cu相的早期析出行为

Precipitation Behavior of Cu-rich Phase in 18Cr9Ni3CuNbN Austenitic Heat-Resistant Steel at Early Aging Stage

应用三维原子探针技术研究了600℃超超临界电站锅炉过热器/再热器用18Cr9Ni3CuNbN奥氏体耐热钢中强化相富Cu相的早期析出行为,并绘制出富Cu相在18Cr-9Ni型奥氏体耐热钢中的C曲线。结果表明:在高温时效过程中富Cu相无论在650℃还是在700℃均能较快地析出,其形成过程都是在短时间内先形成富Cu偏聚区,随着时效时间的延长Cu原子继续扩散到富Cu偏聚区,其它原子如Fe,Cr,Ni等则被排出富Cu偏聚区而扩散到奥氏体基体中,最终形成富Cu相。

The precipitation behavior of the strengthening precipitate Cu-rich phase at the early aging stage in 18Cr9Ni3 Cu Nb N austenitic heat-resistant steel, which is commonly used as tubes for superheater and /or reheater at 600℃ of USC power plants, has been investigated by three dimensional atom probe(3DAP), and C curve of Cu-rich phase in 18Cr-9Ni type steel has been given. Experimental results show that the Cu- rich phase precipitates quickly at the early stage of long- term aging treatment at both650℃ and 700℃. The Cu-rich segregation clusters quickly form and then the Cu atoms diffuse from the gmatrix into the Cu-rich segregation clusters. The atoms of Fe, Cr and Ni from Cu-rich clusters defuse outwards to the g-matrix simultaneously, finally the Cu-rich phase forms.