Fatigue life evaluation of Ti–6Al–4V welded joints manufactured by electron beam melting

Abstract

Electron beam melting (EBM) is a promising three‐dimensional printing technology for the fabrication of components with high complexity and freedom of structural design. However, the major limit for its wider industrial applications is to preclude manufacturing the large‐scale part in one piece. It is because the part size is largely limited by the enclosed vacuum chamber. An alternative option is the use of welding to join EBM‐processed subparts together. In this study, fatigue crack growth (FCG) rate and high‐cycle fatigue (HCF) performance were measured for both EBM‐processed Ti–6Al–4V alloy and its welded joints. An X‐parameter model was then proposed to correlate stress amplitude and geometric parameters (location, size, and shape) of the critical defects at the crack origins with fatigue life. Research framework and result from this work are expected to serve a reference for the defect‐based fatigue life evaluation of welded parts individually manufactured using additive manufacturing.

On micro‐defect induced cracking in very high cycle fatigue regime

“…It mainly consists of three steps: Collect data and construct dataset. The raw dataset according to Z parameter model was collected and constructed from open literatures, and divided into training dataset and validation dataset, as exhibited in Table 2 18,26,44,45 . The inputs include material defect information (size and depth), stress amplitude, fatigue life, stress ratio and temperature. Select an appropriate ML model to obtain fatigue life prediction model by dataset training.…”

Influences of Manufacturing‐Related Microstructural Variations on Fatigue in Carbide‐Rich Tool Steels

“…They also concluded that most fatigue fractures start at manufacturing defects and that defect characteristics such as defect size ffiffiffiffiffiffiffiffi ffi area p , defect location, and morphology are the most important influencing factors on the fatigue life. [46] Murakami et al [9] recently summarized the effect and importance of AM manufacturing defects and surface roughness on the fatigue life. They stated that controlling defects and their size as well as the surface roughness is the key solution for achieving high fatigue strengths for (metallic) AM parts, whereby at the moment the ideal fatigue strength expected from the Vickers hardness can only be achieved with HIP and suitable surface polishing methods.…”

“…In relation to other methods and approaches to describe the HCF and VHCF properties of metals, e.g., from Hu et al, [46] Beretta et al, [54][55][56] or Peng et al [45] with a ML attempt, the provided database here will allow an application, transfer and possible adaptions of these methods for defect-based fatigue also for conventionally (and perhaps AM) manufactured carbide-rich tool steels in future.…”

“…Most of these difficulties can be attributed to other defect types—see refs. [9,10,43–49]—in AM processes (pores, shrinkage cavities, unmelted powder, lack of fusion and bonding defects, surface roughness) compared to conventional ingot cast and PM + HIP tool steels shown in this investigation (carbides, NMI).…”

Random fatigue life prediction of automobile lower arm via modified Corten–Dolan model

“…The current research on fatigue life is mainly divided into fatigue life research in the low cycle fatigue stage (number of stress cycles at material failure less than or equal to ) and high cycle fatigue stage (number of stress cycles at material failure more than ) 1–4 . The fatigue life prediction, 5–9 fatigue damage mechanism, 10–13 and the influence of material manufacturing process on fatigue performance 14,15 for various materials have been a hot topic of research. The fatigue of mechanical components has also been a valuable topic 16,17 …”