The effect of the annealing temperature on the damping capacity under constant prestress, mechanical properties and microstructure of an Fe–11Cr-2.5Mo-0.1Zr-1.0Ni forged damping alloy

A new Fe–11Cr-2.5Mo-0.1Zr-1.0Ni forged damping alloy with dual phases of ferrite and martensite was obtained by an applicable heat treatment to improve the damping capacity under constant prestress. The effect of the annealing temperature on the damping capacity under constant prestress, mechanical properties and microstructure of the alloy was investigated and compared with that of an Fe–16Cr-2.5Mo-0.1Zr forged damping alloy. The Fe–11Cr-2.5Mo-0.1Zr-1.0Ni forged damping alloy annealed at 900 °C comprised dual phases of ferrite and martensite, while the Fe–16Cr-2.5Mo-0.1Zr forged damping alloy annealed at 900 °C comprised single-phase ferrite. The damping results showed that the damping capacity attenuation of the Fe–11Cr-2.5Mo-0.1Zr-1.0Ni forged damping alloy annealed at 900 °C was apparently slower than that of the Fe–16Cr-2.5Mo-0.1Zr forged damping alloy annealed at 900 °C with an increase in the constant prestress. When the strain amplitude γ was 3.88 × 10−5, the damping capacity Q−1 (0.038) of the Fe–11Cr-2.5Mo-0.1Zr-1.0Ni forged damping alloy annealed at 900 °C under a 40 MPa constant prestress maintained 71.7% of that (0.053) of the alloy under an 8 MPa constant prestress. However, the damping capacity Q−1 (0.017) of the Fe–16Cr-2.5Mo-0.1Zr forged damping alloy annealed at 900 °C under a 40 MPa constant prestress was only 35.4% of that (0.048) of the alloy under an 8 MPa constant prestress. According to the TEM results, the ferrite zone in the Fe–11Cr-2.5Mo-0.1Zr-1.0Ni forged damping alloy annealed at 900 °C had not only a moderate dislocation density but also dislocation lines that were almost parallel to each other and moved easily. It can be concluded that the dislocation damping of the Fe–11Cr-2.5Mo-0.1Zr-1.0Ni forged damping alloy annealed at 900 °C was effectively activated and increased as the constant prestress increased.