The grain boundary(GB)damage of long-term crept HR3C(25Cr–20Ni–Nb–N)austenitic steel with solid solution state was investigated by nanoindentation test accompanied with in-situ electron back-scattered diffraction.T...The grain boundary(GB)damage of long-term crept HR3C(25Cr–20Ni–Nb–N)austenitic steel with solid solution state was investigated by nanoindentation test accompanied with in-situ electron back-scattered diffraction.The corresponding microstructure was characterized by scanning electron microscopy and transmission electron microscopy.Results show that the increase in nanoindentation hardness at the GBs and triple grain junctions may be related to the dislocation accumulation and carbide growth during the creep.Coarsened M23C6 and dislocations piling-up at the GB accelerate the nucleation and coalescence of creep cavity along the GB.The nanoindentation hardness in grains varies with orientation of the stress axis.The orientation difference of neighbor grains may induce local high geometrically necessary dislocation densities and strain gradients near the GB,consequently causing stress concentration and subsequent crack growth at specific GBs.展开更多
基金grateful for the financial support from the National Natural Science Foundation of China(51904156,51971163 and 51705082)the Open Fund of Jiangsu Wind Power Engineering Technology Center(ZK22-03-02)the Ten thousand talents project of Zhejiang Province(2019R52056).
文摘The grain boundary(GB)damage of long-term crept HR3C(25Cr–20Ni–Nb–N)austenitic steel with solid solution state was investigated by nanoindentation test accompanied with in-situ electron back-scattered diffraction.The corresponding microstructure was characterized by scanning electron microscopy and transmission electron microscopy.Results show that the increase in nanoindentation hardness at the GBs and triple grain junctions may be related to the dislocation accumulation and carbide growth during the creep.Coarsened M23C6 and dislocations piling-up at the GB accelerate the nucleation and coalescence of creep cavity along the GB.The nanoindentation hardness in grains varies with orientation of the stress axis.The orientation difference of neighbor grains may induce local high geometrically necessary dislocation densities and strain gradients near the GB,consequently causing stress concentration and subsequent crack growth at specific GBs.
