Deformation of novel austenitic heat resist ant steels under extre me environments for th ermal power plants

研究了晶界Fe_2NbLaves相在新型超超临界（A-USC）热电站用奥氏体耐热钢中的强化作用。对不同晶界Laves相面积分数（0-89%）的Fe-20 Cr-30 Ni-2Nb钢的冲击试验表明，裂纹主要在γ-Fe基体的晶内扩展，而不是在Laves相与γ-Fe基体的界面或Laves相内部扩展。对γ-Fe基体中Laves相的纳米压痕实验表明，即使在室温下，也会发生基底滑移塑性变形。因此，迄今为止，Laves相一直被认为是脆性的，它不会降低钢的塑性，并且是奥氏体耐热钢的有希望的强化剂。

We examined a role of grain boundary Fe_2Nb Laves phase in strengthening novel austenitic heat resistant steels for Advanced Ultra-Super Critical(A-USC) thermal power plants. The impact tests for Fe-20Cr-30Ni-2Nb steels with different area fractions of Laves phase on grain boundary(0-89%) revealed that cracks mainly propagate within grain interior ofγ-Fe matrix rather than interfaces between Laves phase andγ-Fe matrix or within Laves phase. The nano-indentation tests for Laves phase inγ-Fe matrix shows that plastic deformation by basal slip would occur at even room temperature. Thus, Laves phase has been believed brittle until now, that never reduce the ductility of steels and is promising strengthener for austenitic heat resistant steels.