Effect of hydrogen-charged treatment on the biaxial cyclic deformation behavior of cold-worked Zr-4

The effects of hydrogen-charged treatment on the biaxial cyclic deformation behavior and the fatigue lifetime of cold-worked Zr-4 have been investigated. The results show that the fatigue lifetime of hydrogenated Zr-4 under the cold-worked condition with C_H =400 μg/g is better than that of the unhydrogenated one. Whereas, when C_H = 580 μg/g, the fatigue lifetime of cold-worked hydrogenated Zr-4 alloy is lower than that of the unhydrogenated Zr-4 at the equivalent strain amplitudes (Δε_eq = 0.8%) and the same phase angle (φ). Microstructure examination by means of TEM and optical microscope reveals that the improvement of fatigue lifetime for the hydrogenated Zr-4 alloy in the low hydrogen concentration can be attributed to the relieve of the residual stress during hydrogenating treatment at elevated temperature, which leads to the good abilities of plastic deformation and harmony with matrix for hydride formed in Zr-4.