20Cr11MoVNbNB钢的蠕变性能与组织的关系

RELATIONSHIP BETWEEN CREEP PROPERTIES AND STRUCTURE OF STEEL 20Cr11MoVNbNB

研究了20Cr11MoVNbNB钢550—650℃的蠕变性能及组织的变化,发现在550℃,蠕变应力>180MPa时,过渡蠕变应变和蠕变时间的ε_β-ι^(1/3)关系中,呈现前期斜率β_1大于后期β_2的两段线性关系;550℃稳态蠕变速率可用■=Aσ~nexp(-Q_c/RT)来表示,其中n=4.7,Aexp(-Q_c/RT)=5.37×10_(-16);550—650℃的表观蠕变激活能Q_c=430kJ/mol,其值远大于基体Fe原子的自扩散激活能;发现在蠕变过程中,随蠕变应力和蠕变时间增加,沉淀相的总量和其中的Cr,Mo,V含量增加,Fe和Nb含量则下降。

Studies were made of the creep properties and structure change of steel 20Cr11MoVNbNB at 550—650℃. It is found that at 550℃ when creep stress > 180MPa, there exists linear relation with two different slopes β_1 and β_2 between transitional creep strain ε_β and creep time t^(1/3), and β_1 (in initiol period) > β_2 (in later period). The Creep rate of stable stage at 550℃ can be expressed as ε_(11) = Aσ~nexp(-Q_c/RT), where, n=4.7, A exp(-Q_c/RT) = 5.37×10^(-16). Apparent creep active energy Q_c= 430kJ/mol at 550-650℃, which is much higher than the self-diffusion active energy of atoms for matrix Fe. In creep process, as creep stress and time increase, total weight of precipitated phases and relative weight of Cr, Mo and V increase, but those of Fe and Nb decrease in precipitated phases.