scholarly journals Fatigue Crack Growth in Maraging Steel Obtained by Selective Laser Melting

2019 ◽  
Vol 9 (20) ◽  
pp. 4412 ◽  
Author(s):  
Fernando Antunes ◽  
Luís Santos ◽  
Carlos Capela ◽  
José Ferreira ◽  
José Costa ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Selective Laser Melting ◽  
High Surface ◽  
Laser Melting ◽  
Controlling Mechanism ◽  
Cyclic Plastic Deformation ◽  
Plasticity Induced Crack Closure

Selective Laser Melting (SLM) is an additive manufacturing technology, ideal for the production of complex-shaped components. Design against fatigue is fundamental in the presence of cyclic loads, particularly for these materials which typically have significant porosity, high surface roughness and residual stresses. The main objective here is to study fatigue crack growth (FCG) in the 18Ni300 steel obtained by SLM. Typical da/dN-ΔK curves were obtained in C(T) specimens, indicating that cyclic plastic deformation may be the controlling mechanism. A complementary analysis, based on plastic CTOD range, showed a relatively low level of crack tip plastic deformation, and consequently a reduced level of plasticity induced crack closure. The curve da/dN versus plastic CTOD range is clearly above the curves for other materials.

Fatigue Crack Growth Rates and Tensile Strength of Titanium Produced by Means of Selective Laser Melting

2014 ◽  
Vol 627 ◽  
pp. 305-308 ◽  
Author(s):  
Tomasz Brynk ◽  
Barbara Romelczyk ◽  
Zbigniew Pakiela ◽  
Tomasz Kurzynowski ◽  
Edward Chlebus
Keyword(s):  
Mechanical Properties ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Selective Laser Melting ◽  
Pure Titanium ◽  
Tensile Tests ◽  
Image Correlation ◽  
Laser Melting ◽  
Full Field

Mini-samples technique was utilized to determine mechanical properties of technically pure titanium produced by means of selective laser melting (SLM). Full-field digital image correlation (DIC) measurements and inverse method were applied for crack tip position and stress intensity factors calculations in the case of fatigue crack growth rate tests. DIC was also used for strain measurement during tensile tests on sub sized samples. There was studied the influence of samples orientation on the mechanical properties of mini-samples. Samples were cut out from rectangular cubes and were oriented with 0°, 45° or 90° angle to the direction of laser beam travel. There were also tested samples directly produced via SLM. Additionally microstructure observations were performed to verify the quality of SLM processed materials and explain mechanical properties variations.

Fatigue crack growth rate and tensile strength of Re modified Inconel 718 produced by means of selective laser melting

2017 ◽  
Vol 698 ◽  
pp. 289-301 ◽  
Author(s):  
Tomasz Brynk ◽  
Zbigniew Pakiela ◽  
Kinga Ludwichowska ◽  
Barbara Romelczyk ◽  
Rafal M. Molak ◽  
...  
Keyword(s):  
Growth Rate ◽  
Tensile Strength ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Selective Laser Melting ◽  
Fatigue Crack Growth Rate ◽  
Inconel 718 ◽  
Laser Melting

scholarly journals Numerical Prediction of the Fatigue Crack Growth Rate in SLM Ti-6Al-4V Based on Crack Tip Plastic Strain

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1133
Author(s):  
Fábio F. Ferreira ◽  
Diogo M. Neto ◽  
Joel S. Jesus ◽  
Pedro A. Prates ◽  
Fernando V. Antunes
Keyword(s):  
Growth Rate ◽  
Plastic Deformation ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Plastic Strain ◽  
Crack Growth ◽  
Stress Ratio ◽  
Cyclic Plastic ◽  
Cyclic Plastic Deformation

This study presents a numerical model to predict the fatigue crack growth (FCG) rate in compact tension specimens under constant amplitude cyclic loadings. The material studied is the Ti-6Al-4V titanium alloy produced by selective laser melting, which was submitted to two different post-treatments: (i) hot isostatic pressing, and (ii) heat treatment. The developed finite element model uses the cumulative plastic strain at the crack tip to define the nodal release. Two different FCG criteria are presented, namely the incremental plastic strain (IPS) criterion and the total plastic strain (TPS) criterion. The calibration of the elasto-plastic constitutive model was carried out using experimental data from low cycle fatigue tests of smooth specimens. For both proposed crack growth criteria, the predicted da/dN-ΔK curve is approximately linear in log-log scale. However, the slope of the curve is higher using the TPS criterion. The numerical predictions of the crack growth rate are in good agreement with the experimental results, which indicates that cyclic plastic deformation is the main damage mechanism. The numerical results showed that increasing the stress ratio leads to a shift up of the da/dN-ΔK curve. The effect of stress ratio was dissociated from variations of cyclic plastic deformation, and an extrinsic mechanism, i.e., crack closure phenomenon, was found to be the cause.

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