Environmentally-assisted Fatigue Crack Growth in AA7050-T73511 Al Alloy and AA2050-T84 Al-Cu-Li Alloy

Materials Research

Jéferson Aparecido Moreto¹  Fernando Antônio Paschoal Júnior¹  Carla Isabel Santos Maciel¹  Luis Henrique Camargo Bonazzi¹  José Francisco Leonelli Júnior¹  Cassius Olívio Figueiredo Terra Ruchert¹  Waldek Wladimir Bose Filho¹ 

关键词: Al-Li alloys;    low temperature;    corrosion-fatigue;    seawater fog;   

DOI  :  10.1590/1516-1439.018915

来源: SciELO

【 摘 要 】

The aim of this study was to evaluate and compare the effect of low temperature and saline environment on the fatigue crack growth behavior of the AA7050-T7451 Al alloy and the recently developed AA2050-T Al-Cu-Li alloy. Fatigue at room and low temperature and corrosion-fatigue tests were carried out using an applied stress ratio (R) of 0.1, 15 Hz frequency (air at RT and –54 °C) and 1 Hz frequency (seawater fog) using a sinusoidal wave form. In the near-threshold region, in air and at RT it was found a ΔKth = 2.9 MPa.m1/2 for AA2050-T84, in saline environment this value increased to ΔKth = 4.9 MPa.m1/2, due to closure effect through wedge effect by the corrosion products. At the beginning of the Paris-Erdogan region, the crack closure effect was not present for the AA7050-T7451, but persisted for the AA2050 Al-li alloy. It was observed that both alloys were equally affected by temperature reduction. When the saline environment is considered it was observed that the AA7050-T7451 presents lower m value (2.6) than the one for AA2050-T84 (3.4), meaning a lower FCG rate variation with ΔK, however it presented the highest C value, as a consequence the worst FCG behavior.

【 授权许可】

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