The low cycle fatigue strength properties of the additively manufactured Ti-6Al-4V alloy are experimentally investigated under proportional and nonproportional multiaxial loading. The fatigue tests were conducted using hollow cylinder specimens with and without heat treatments, at room temperature in air. Two fatigue tests were conducted:one for proportional loading and one for nonproportional loading. The proportional loading was represented by a push-pull strain path (PP) and the nonproportional loading by a circle strain path (CI). The failure lives of the additively manufactured specimens were clearly reduced drastically by internal voids and defects. However, the sizes of the defects were measured, and the defects were found not to cause a reduction in fatigue strength above a critical size. The fracture surface was observed using scanning electron microscopy to investigate the fracture mechanisms of the additively manufactured specimens under the two types of strain paths. Different fracture patterns were recognized for each strain paths; however, both showed retention of the crack propagation, despite the presence of numerous defects, probably because of the interaction of the defects. The crack propagation properties of the materials with numerous defects under nonproportional multiaxial loading were clarified to increase the reliability of the additively manufactured components.
Yuya Kimura
,
Fumio Ogawa
,
Takamoto Itoh
. Fatigue Property of Additively Manufactured Ti-6Al-4V under Nonproportional Multiaxial Loading[J]. Chinese Journal of Mechanical Engineering, 2021
, 34(6)
: 103
-103
.
DOI: 10.1186/s10033-021-00626-8
The low cycle fatigue strength properties of the additively manufactured Ti-6Al-4V alloy are experimentally investigated under proportional and nonproportional multiaxial loading. The fatigue tests were conducted using hollow cylinder specimens with and without heat treatments, at room temperature in air. Two fatigue tests were conducted:one for proportional loading and one for nonproportional loading. The proportional loading was represented by a push-pull strain path (PP) and the nonproportional loading by a circle strain path (CI). The failure lives of the additively manufactured specimens were clearly reduced drastically by internal voids and defects. However, the sizes of the defects were measured, and the defects were found not to cause a reduction in fatigue strength above a critical size. The fracture surface was observed using scanning electron microscopy to investigate the fracture mechanisms of the additively manufactured specimens under the two types of strain paths. Different fracture patterns were recognized for each strain paths; however, both showed retention of the crack propagation, despite the presence of numerous defects, probably because of the interaction of the defects. The crack propagation properties of the materials with numerous defects under nonproportional multiaxial loading were clarified to increase the reliability of the additively manufactured components.
[1] N Nadammal, T Mishurova, T Fritsch, et al. Critical role of scan strategies on the development of microstructure, texture, and residual stresses during laser powder bed fusion additive manufacuturing. Additive Manufacturing, 2021, 38:101792.
[2] S C Bodner, L T G van de Vorst, J Zalesak, et al. Inconel-steel multilayers by liquid dispersed metal powder bed fusion:Microstructure, residual stress and property gradients. Additive Manufacturing, 2020, 32:101027.
[3] M Muhammad, P D Nezhadfar, S Thompson, et al. A comparative investigation on the microstructure and mechanical properties of additively manufactured aluminum alloys. International Journal of Fatigue, 2021, 146:106165.
[4] J Deckers, J Vleugels, J P Kruth. Additive manufacturing of ceramics:A review. Journal of Ceramics Science and Technology, 2014, 5(4):245-260.
[5] P Mercelis, J Kruth. Residual stresses in selective laser sintering and selective laser melting. Rapid Prototyping Journal, 2006, 12(5):254-265.
[6] M Shiomi, K Osakada, K Nakamura, et al. Residual stress within metallic model made by selective laser melting process. CIRP Annals, 2004, 53(1):195-198.
[7] S Leuders, M Thöne, A Riemer, et al. On the mechanical behaviour of titanium alloy TiAl6V4 manufactured by selective laser melting:Fatigue resistance and crack growth performance. International Journal of Fatigue, 2013, 48:300-307.
[8] B Baufeld, E Brandl, O van der Biest. Wire based additive layer manufacturing:Comparison of microstructure and mechanical properties of Ti-6Al-4V components fabricated by laser-beam deposition and shaped metal deposition. Journal of Materials Processing Technology, 2011, 211(6):1146-1158.
[9] A Fatemi, R Molaei, S Sharifimehr, et al. Torsional fatigue behavior of wrought and additive manufactured Ti-6Al-4V by powder bed fusion including surface finish effect. International Journal of Fatigue, 2017, 100:347-366.
[10] A Fatemi, R Molaei, S Sharifimehr, et al. Multiaxial fatigue behavior of wrought and additive manufactured Ti-6Al-4V by powder bed fusion including surface finish effect. International Journal of Fatigue, 2017, 99:187-201.
[11] S Lee, J W Pegues, N Shamsaei. Fatigue behavior and modeling for additive manufactured 304L stainless steel:The effect of surface roughness. International Journal of Fatigue, 2020, 141:105856.
[12] L Sheridan, J E Gockel, O E Scott-Emuakpor. Stress-defect-life interactions of fatigued additively manufactured alloy 718. International Journal of Fatigue, 2021, 143:106033.
[13] P Li, D H Warner, A Fatemi, et al. Critical assessment of the fatigue performance of additively manufactured Ti-6Al-4V and perspective for future research. International Journal of Fatigue, 2016, 85:130-143.
[14] A Sterling, N Shamsaei, B Torries, et al. Fatigue behaviour of additively manufactured Ti-6Al-4V. Procedia Engineering, 2015, 133:576-589.
[15] K Kanazawa, K J Miller, M W Brown. Cyclic deformation of 1% Cr-Mo-V steel under out-of-phase loads. Fatigue and Fracture of Engineering Materials and Structures, 1979, 2(2):217-228.
[16] E Krempl, H Lu. Comparison of the stress responses of an aluminum alloy tube to proportional and alternate axial and shear strain paths at room temperature. Mechanics of Materials, 1983, 2(3):183-192.
[17] T Itoh, M Sakane, M Ohnami, et al. Effect of stacking fault energy on cyclic constitutive relation under nonproportional loading. Journal of the Society of Materials Science, Japan, 1992, 41(468):1361-1367.
[18] T Itoh, T Yang. Material dependence of multiaxial low cycle fatigue lives under nonproportional loading. International Journal of Fatigue, 2011, 33(8):1025-1031.
[19] M Wu, T Itoh, Y Shimizu, et al. Low cycle fatigue life of Ti-6Al-4V alloy under non-proportional loading. International Journal of Fatigue, 2012, 44:14-20.
[20] T Nakano. Additive manufacturing for titanium and its alloys. The Japan Institute of Light Metals, 2017, 67(9):470-480.
[21] J W Pegues, S Shao, N Shamsaei, et al. Fatigue of additive manufactured Ti-6Al-4V, Part I:The effects of powder feed stock, manufacturing, and post process conditions on the resulting microstructure and defects. International Journal of Fatigue, 2020, 132:105358.
[22] N Molaei, A Fatemi, N Phan. Notched fatigue of additive manufactured metals under uniaxial and multiaxial loadings, Part I:Effects of surface roughness and HIP and comparisons with their wrought alloys. International Journal of Fatigue, 2021, 143:106003.
[23] S Bressan, F Ogawa, T Itoh, et al. Cyclic plastic behavior of additively manufactured Ti-6Al-4V under uniaxial and multiaxial non-proportional loading. International Journal of Fatigue, 2019, 126:155-164.
[24] T Nakano, T Ishimoto. Powder-based additive manufacturing for development of tailor-made implants for orthopedic applications. KONA Powder and Particle Journal, 2015, 32:75-84.
