Proposal of Fatigue Limit Design Curves for Additively Manufactured Ti-6Al-4V in a VHCF Regime Using Specimens with Artificial Defects

Cantilever-type rotating bending fatigue tests were conducted under a very high cycle fatigue regime using conventionally manufactured Ti-6Al-4V specimens having drilled artificial defects with different sizes. The relationship between fatigue limit and defect size was defined as a fatigue limit design curve considering the transition from the fracture-mechanics dominating area to the fatigue-limit dominating area. A conventional Murakami's equation was applicable as a design curve of additively manufactured Ti-6Al-4V with defects at 10(7) cycles. However, conventional equation gave un-conservative predictions for the fatigue limit at 10(8) cycles. Therefore, two kinds of modified Murakami's equation were proposed as fatigue limit design curves for the very high cycle fatigue regime. Simple parallel shift of Murakami's equation gave a conservative fatigue limit, whilst better result was obtained by changing the slope of Murakami's equation. The proposed design curve was valid for the defect sizes ranging from 10 to 500 mu m.

Automated summary

Cantilever-type rotating bending fatigue tests were conducted to study the relationship between fatigue limit and defect size under very high cycle fatigue regime, proposing specific design curves for different scenarios by modifying Murakami's equation.