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

研究了晶界Fe2Nb Laves相在强化新型超超临界(A-USC)热电厂用奥氏体耐热钢中的作用。对Laves相晶界面积分数不同(0-89%)的Fe-20Cr30Ni-2Nb钢的冲击试验表明，裂纹主要在γ-Fe晶内扩展，而不是在γ-Fe相界面上或在Laves相内扩展。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面滑移塑性变形。因此，到目前为止，Laves相一直被认为是脆性的，它从未降低钢的塑性，是很有前途的奥氏体耐热钢的强化剂。

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.