Electron Backscattered Diffraction Investigation of Grain Boundary Creep Damage Features of HR3C Austenitic Heat-resistant Steel

Abstract:

In order to investigate the intergranular fracture characteristics of HR3C austenitic heat-resistant steel at various creed rates， several techniques are employed to test the properties and observe the microstructure evolution. The quantitative electron backscatter diffraction （EBSD） analysis results show that creep strain has little effect on the grain size， and grains do not exhibit a preferred orientation or no obvious texture after crept at different creep rates. The lowest proportion of low Σ CSL grain boundaries at 150 MPa implies that the primary twin structures is preserved at a low creep rate， while some twin structures are evolved into general grain boundaries at a high creep rate. The EBSD analysis methods well describe the creep micro-strain distribution， which shows that the creep strain is inhomogeneous between grains and strain occurs mostly close to grain boundaries and induces grain boundary migration. The generation and propagation of intergranular microcracks and creep voids are the most significant damage characteristics. These damage phenomena are closely related to the creep rates and the character of the grain boundaries.