Fatigue Crack Growth in Maraging Steel Obtained by Selective Laser Melting

Capela, Carlos; Lima Santos, Luís; Antunes, Fernando; Ferreira, José; Costa, José; Jesus, Joel; Prates, Pedro

http://hdl.handle.net/10400.8/13026

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Abstract(s)

The fatigue crack growth properties of G20Mn5QT cast steel and corresponding butt welds, using compact tension specimens, were monitored and investigated via acoustic emission (AE) techniques. Fatigue crack growth is a combination of cyclic plastic deformations before the crack tip, tensile crack fractures, and shear crack fractures. The cyclic plastic deformations release the maximum amount of energy, which accounts for half of the total energy, and the second-largest number of AE signals, which are of the continuous-wave type. The tensile crack fractures release the second-largest amount of energy and the largest number of AE signals, which are of the burst-wave type. The shear crack fractures release the least amount of energy and the lowest number of AE signals, which are similar to the burst type, albeit with a relatively longer rise time and duration. Crack tip advancement can be regarded as a discontinuous process. The critical area before the crack tip brittlely ruptures when the fatigue damage caused by cyclic plastic deformations reaches critical status. The ruptures produce a large number of tensile crack fractures and rare shear crack fractures. Through fractography observation, the shear crack fractures occur probabilistically around defects caused by casting or welding, which lead to stress and strain in the local complex.

Description

Applied Sciences (Switzerland)Open AccessVolume 9, Issue 201 October 2019 Article number 4412

Keywords

fatigue crack growth Selective Laser Melting (SLM) Crack tip Opening Displacement (CTOD) crack tip plastic deformation

URI

http://hdl.handle.net/10400.8/13026

Citation

Antunes, F., Santos, L., Capela, C., Ferreira, J., Costa, J., Jesus, J., & Prates, P. (2019). Fatigue Crack Growth in Maraging Steel Obtained by Selective Laser Melting. Applied Sciences, 9(20), 4412. https://doi.org/10.3390/app9204412