ISSN 0412-1961
CN 21-1139/TG
Started in 1956

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 , Volume 58 Issue 12 Previous Issue    Next Issue
 Select Constraint Related Fatigue Crack Initiation Life of GH4169 Superalloy GUO Haohan, YANG Jie, LIU Fang, LU Rongsheng Acta Metall Sin, 2022, 58 (12): 1633-1644.  DOI: 10.11900/0412.1961.2022.00099 Abstract   HTML   PDF (3733KB) ( 190 ) Nickel-based GH4169 superalloy is used as turbine disc material in aeroengines because of its good oxidation resistance, good formability, weldability, and high strength. However, turbine disc fatigue failure will inevitably occur in onerous service environments and after a long operation time. To ensure the safety and reliability of aeroengines, the fatigue damage behavior and fatigue life of GH4169 superalloy need to be studied. Constraint is an important factor affecting the fatigue fracture behavior of materials, because changing it will impact the fatigue behavior. To achieve a long service life and high reliability of aeroengines, fatigue and constraint effects must be researched. However, there are only limited studies on the effect of constraint on fatigue crack initiation time. In this study, a crystal plasticity constitutive model based on low cycle fatigue rate correlation was applied to the GH4169 superalloy. Two fatigue indicators, namely the cumulated energy dissipation and cumulated plastic slip, were introduced as fatigue crack initiation criteria to study the fatigue crack initiation time for different micro-notch depths and lengths. In addition, the relationship between constraint and fatigue crack initiation life was further investigated using the unified constraint parameter Ap. The results showed that both cumulated energy dissipation and cumulated plastic slip can accurately predict the fatigue crack initiation time. With the increase in micro-notch depth, the fatigue crack initiation time decreased, while it increased with the increase in micro-notch length. A linear relationship between the fatigue crack initiation time and $Ap$ under different micro-notch depths and lengths was observed. Based on this relationship, the constraint related to the fatigue crack initiation time can be determined.