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

我们研究了晶界Fe_2Nb Laves相在强化先进超超临界（a- usc）火力发电厂用新型奥氏体耐热钢中的作用。对晶界上Laves相面积分数不同（0 ~ 89%）的Fe-20Cr-30Ni-2Nb钢进行冲击试验表明，裂纹主要在γ- fe基体的晶粒内部扩展，而不是在Laves相与γ- fe基体的界面或Laves相内部扩展。γ- fe基体中Laves相的纳米压痕试验表明，在均匀室温条件下，基底滑移会引起塑性变形。因此，到目前为止，Laves相一直被认为是脆性的，不会降低钢的延展性，是奥氏体耐热钢的有前途的增强剂。

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.