Effect of Ultrasonic Surface Rolling Process on Pre-corrosion Fatigue Behavior of Zr705 Alloy
The fatigue properties of Zr705 alloy in original state and ultrasonic surface rolling(USRP)state after pre-corrosion in 1 mol/L LiOH solution,3.5％NaCl solution and 5％HCl solution for 30 d were studied.The results show that the corrosion degree of the original Zr705 alloy is the most serious in 3.5％NaCl solution,followed by in 5％HCl solution and the least in 1 mol/L LiOH solution.This is related to the different corrosion mechanisms of Zr705 alloy in different media.USRP-Zr705 alloy is more susceptible to corrosion than the original Zr705 alloy because of the high density dislocation defects in the surface gradient structure.After immersion corrosion treatment,the fatigue life of the original Zr705 alloy decreases obviously,which is mainly caused by corrosion damage on the surface of the sample during immersion corrosion.After immersion corrosion treatment,the fatigue life of USRP-Zr705 sample in 1 mol/L LiOH solution is higher than that of the original Zr705 alloy,but it is lower in 3.5％NaCl solution and 5％HCl solution.There is a competitive relationship between the corrosion environment and the surface gradient structure on the fatigue properties of zirconium alloys.When the corrosion medium is weak,the surface gradient structure is the main factor affecting the fatigue properties of zirconium alloys.When the corrosive medium is strong,the surface gradient structure is still the main factor affecting the fatigue properties under high stress cyclic loading.Under low stress cyclic loading,corrosion environment is the main factor affecting the fatigue properties.
Zr705 alloyultrasonic surface rolling processsurface gradient structurecorrosion behaviorpre-corrosion fatigue
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