Microstructural Evolution of X20CrMoV12.1 Steel upon Short-term Creep Rupture Test
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In this work, microstructural and hardness evolution of the X20 steel upon short-term creep test (550oC to 650oC, 180oC to 60 MPa) was studied by using scanning electron microscope, electron backscattered diffraction, and transmission electron microscope, microhardness tester. After creep rupture, gauge and grip part of the specimens were microstructurally analyzed. Creep at the 650oC/60 MPa resulted in a rupture at 1,460 hours with growth of lath width from 1.31 to 2.87 μm and a grain growth with a more equiaxed feature. There is a close relationship between Microhardness and lath width. The formation and coarsening of Laves phase, which was observed up to 600oC of creep temperature, was accelerated by the applied stress. Slight coarsening of the M23C6 was observed in the 550oC and 600oC crept or aged specimens. The coarsening of M23C6 depended on the temperature, where specimens crept at 650oC showed higher growth rate. The microstructural evolution of X20 after short-term creep test was extensively discussed in relation to the long-term creep/aging test reported in literatures.
Abstract
In this work, microstructural and hardness evolution of the X20 steel upon short-term creep test (550oC to 650oC, 180oC to 60 MPa) was studied by using scanning electron microscope, electron backscattered diffraction, and transmission electron microscope, microhardness tester. After creep rupture, gauge and grip part of the specimens were microstructurally analyzed. Creep at the 650oC/60 MPa resulted in a rupture at 1,460 hours with growth of lath width from 1.31 to 2.87 μm and a grain growth with a more equiaxed feature. There is a close relationship between Microhardness and lath width. The formation and coarsening of Laves phase, which was observed up to 600oC of creep temperature, was accelerated by the applied stress. Slight coarsening of the M23C6 was observed in the 550oC and 600oC crept or aged specimens. The coarsening of M23C6 depended on the temperature, where specimens crept at 650oC showed higher growth rate. The microstructural evolution of X20 after short-term creep test was extensively discussed in relation to the long-term creep/aging test reported in literatures.
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