scholarly journals Analysis of the Thermomechanical Fatigue Behavior of Fully Ferritic High Chromium Steel Crofer®22 H with Cyclic Indentation Testing

2020 ◽  
Vol 10 (18) ◽  
pp. 6461 ◽  
Author(s):  
Bastian Blinn ◽  
David Görzen ◽  
Torsten Fischer ◽  
Bernd Kuhn ◽  
Tilmann Beck
Keyword(s):  
Deformation Behavior ◽  
Damage Tolerance ◽  
Fatigue Behavior ◽  
Failure Mechanisms ◽  
Cyclic Hardening ◽  
Thermomechanical Fatigue ◽  
Chromium Steel ◽  
Indentation Tests ◽  
Cyclic Indentation ◽  
Induced Changes

The 22 wt.% Cr, fully ferritic stainless steel Crofer®22 H has higher thermomechanical fatigue (TMF)- lifetime compared to advanced ferritic-martensitic P91, which is assumed to be caused by different damage tolerance, leading to differences in crack propagation and failure mechanisms. To analyze this, instrumented cyclic indentation tests (CITs) were used because the material’s cyclic hardening potential—which strongly correlates with damage tolerance, can be determined by analyzing the deformation behavior in CITs. In the presented work, CITs were performed for both materials at specimens loaded for different numbers of TMF-cycles. These investigations show higher damage tolerance for Crofer®22 H and demonstrate changes in damage tolerance during TMF-loading for both materials, which correlates with the cyclic deformation behavior observed in TMF-tests. Furthermore, the results obtained at Crofer®22 H indicate an increase of damage tolerance in the second half of TMF-lifetime, which cannot be observed for P91. Moreover, CITs were performed at Crofer®22 H in the vicinity of a fatigue crack, enabling to locally analyze the damage tolerance. These CITs show differences between crack edges and the crack tip. Conclusively, the presented results demonstrate that CITs can be utilized to analyze TMF-induced changes in damage tolerance.

Influence of Cyclic Deformation Induced Phase Transformation on the Fatigue Behavior of the Austenitic Steel X6CrNiNb1810

2014 ◽  
Vol 891-892 ◽  
pp. 1231-1236 ◽  
Author(s):  
Andreas Sorich ◽  
Marek Smaga ◽  
Dietmar Eifler
Keyword(s):  
Phase Transformation ◽  
Fatigue Life ◽  
Austenitic Steel ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Fatigue Behavior ◽  
Cyclic Hardening ◽  
Martensite Formation ◽  
Destructive Testing

The austenitic steel X6CrNiNb1810 (AISI 347) was investigated in isothermal total strain-controlled tests at ambient temperature and T = 300 °C in the LCF-and HCF-range. The phase transformation from paramagnetic austenite (fcc) into ferromagnetic α´-martensite ́(bcc) leads to cyclic hardening and to an increase in fatigue life. At 300 °C no α´-martensite formation was observed in the LCF-range and the cyclic deformation behavior depends basically on cyclic hardening processes due to an increase of the dislocation density, followed by cyclic saturation and softening due to changes in the dislocation structure. In the HCF-range an increase in fatigue life was observed due to ε- and α´-martensite formation. Measurements of the mechanical stress-strain-hysteresis as well as temperature and magnetic properties enable a characterization of the cyclic deformation behavior and phase transformation in detail. The changes in the physical data were interpreted via microstructural changes observed by scanning-and transmission-electron-microscopy as well as by x-ray investigations. Additionally electromagnetic acoustic transducers (EMATs) developed from the Fraunhofer Institute of Non-destructive Testing (IZFP) Saarbrücken were used for an in-situ characterization of the fatigue processes.

Investigating the Influence of Process Parameters on the Mechanical Properties of Extruded Aluminum Tubes by Cyclic Indentation Tests

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 744
Author(s):  
David Görzen ◽  
Florian Patrick Schäfke ◽  
Bastian Blinn ◽  
Christian Klose ◽  
Hans Jürgen Maier ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Process Condition ◽  
Cyclic Hardening ◽  
Extrusion Process ◽  
Subsequent Heat Treatment ◽  
Al Alloy ◽  
Influence Of Process Parameters ◽  
Indentation Tests ◽  
Cyclic Indentation

Given the complex process condition, extruded aluminum (Al) alloy tubes show locally pronounced differences in microstructure and mechanical properties, which can be influenced by subsequent heat treatment. In the present study, cyclic indentation tests (CITs) were conducted on extruded Al alloy EN AW-6082 to locally determine hardness and cyclic hardening potential, which was complemented with light optical microscopy. To analyze the influence of extrusion process and subsequent heat treatment, the EN AW-6082 tubes investigated were manufactured with extrusion ratios Ψ of 13:1 and 22:1, both in as-extruded and T6 heat-treated conditions. The results obtained for the as-extruded state showed significant differences of the local mechanical properties and demonstrated that an increased Ψ leads to higher hardness, caused by more pronounced plastic deformation during the manufacturing process. Moreover, an increase of hardness and cyclic hardening potential was observed after a T6 heat treatment, which also reduced the difference in hardness between the different extrusion ratios. Additionally, the pronounced local differences in hardness and cyclic hardening potential correlated with the local microstructure. The results demonstrated that CITs enable the analysis of local mechanical properties of extruded EN AW-6082 profiles, resulting from different extrusions ratios as well as subsequent heat treatment.

Residual Stress Relaxation and Cyclic Deformation Behavior of Deep Rolled AlMg4.5Mn (AA5083) at Elevated Temperatures

2005 ◽  
Vol 490-491 ◽  
pp. 436-441 ◽  
Author(s):  
P. Juijerm ◽  
I. Altenberger ◽  
U. Noster ◽  
Berthold Scholtes
Keyword(s):  
Work Hardening ◽  
Deformation Behavior ◽  
Fatigue Behavior ◽  
Cyclic Hardening ◽  
Fatigue Tests ◽  
Plastic Strain Amplitude ◽  
Deep Rolling ◽  
Near Surface ◽  
Surface Work ◽  
Compressive Residual Stresses

The cyclic deformation behavior of deep rolled and polished aluminium wrought alloy AlMg4,5Mn in the temperature range 20-300°C has been investigated. Results of quasistatic tension and compression tests of untreated specimens in the temperature range 20-300°C are presented. To characterize the fatigue behavior for stress-controlled tests as a function of test temperature, s-n curves, cyclic deformations curves and mean strains as a function of number of cycles are given. The residual stress- and work hardening states near the surface of deep rolled aluminium alloy AlMg4.5Mn before and after fatigue tests were investigated by X-ray diffraction methods. The investigated AlMn4.5Mn aluminium alloy shows cyclic hardening until fracture at all stress amplitudes in stress-controlled fatigue tests at 25-150°C. With increasing temperature the deformation behavior shifts from cyclic hardening to cyclic softening. Below a certain stress amplitude at a given temperature deep rolling led to a reduction of the plastic strain amplitude as compared to the untreated state through cyclically stable near-surface work hardening as indicated by stable FWHM-values. This reduction in plastic strain amplitude is associated with enhanced fatigue lives. The effectiveness of deep rolling is governed by the cyclic and thermal stability of nearsurface work hardening rather than macroscopic compressive residual stresses. Since nearsurface work hardening is known to retard crack initiation, deep rolling is also effective in temperature- and stress ranges where macroscopic compressive residual stresses have relaxed almost completely, but where near-surface work hardening prevails. Above certain stress amplitudes and temperatures, deep rolling has no beneficial effect on the fatigue behavior of AlMg4.5Mn. This is a consequence of instable near-surface microstructures, especially instable near-surface work hardening.

scholarly journals Influence of the Chemical Composition of the Used Powder on the Fatigue Behavior of Additively Manufactured Materials

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1285
Author(s):  
Bastian Blinn ◽  
Florian Krebs ◽  
Maximilian Ley ◽  
Christopher Gläßner ◽  
Marek Smaga ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Chemical Composition ◽  
Fatigue Behavior ◽  
Fatigue Properties ◽  
Defect Tolerance ◽  
Microstructural Defects ◽  
Physically Based ◽  
Load Increase ◽  
Indentation Tests ◽  
Cyclic Indentation

To exploit the whole potential of Additive Manufacturing (AM), a sound knowledge about the mechanical and especially cyclic properties of AM materials as well as their dependency on the process parameters is indispensable. In the presented work, the influence of chemical composition of the used powder on the fatigue behavior of Selectively Laser Melted (SLM) and Laser Deposition Welded (LDW) specimens made of austenitic stainless steel AISI 316L was investigated. Therefore, in each manufacturing process two variations of chemical composition of the used powder were utilized. For qualitative characterization of the materials cyclic deformation behavior, load increase tests (LITs) were performed and further used for the physically based lifetime calculation method (PhyBaLLIT), enabling an efficient determination of stress (S)–number of cycles to failure (Nf) curves (S–Nf), which show excellent correlation to additionally performed constant amplitude tests (CATs). Moreover, instrumented cyclic indentation tests (PhyBaLCHT) were utilized to characterize the materials’ defect tolerance in a comparably short time. All material variants exhibit a high influence of microstructural defects on the fatigue properties. Consequently, for the SLM process a higher fatigue lifetime at lower stress amplitudes could be observed for the batch with a higher defect tolerance, resulting from a more pronounced deformation induced austenite–α’-martensite transformation. In correspondence to that, the batch of LDW material with an increased defect tolerance exhibit a higher fatigue strength. However, the differences in defect tolerance between the LDW batches is only slightly influenced by phase transformation and seems to be mainly governed by differences in hardening potential of the austenitic microstructure. Furthermore, a significantly higher fatigue strength could be observed for SLM material in relation to LDW specimens, because of a refined microstructure and smaller microstructural defects of SLM specimens.

scholarly journals Analysis of Hydrogen-Induced Changes in the Cyclic Deformation Behavior of AISI 300–Series Austenitic Stainless Steels Using Cyclic Indentation Testing

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 923
Author(s):  
Sven Brück ◽  
Bastian Blinn ◽  
Katharina Diehl ◽  
Yannick Wissing ◽  
Julian Müller ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Growth ◽  
Stainless Steels ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Fatigue Cracks ◽  
Austenitic Stainless Steels ◽  
Indentation Testing ◽  
Indentation Tests ◽  
Cyclic Indentation

The locally occurring mechanisms of hydrogen embrittlement significantly influence the fatigue behavior of a material, which was shown in previous research on two different AISI 300-series austenitic stainless steels with different austenite stabilities. In this preliminary work, an enhanced fatigue crack growth as well as changes in crack initiation sites and morphology caused by hydrogen were observed. To further analyze the results obtained in this previous research, in the present work the local cyclic deformation behavior of the material volume was analyzed by using cyclic indentation testing. Moreover, these results were correlated to the local dislocation structures obtained with transmission electron microscopy (TEM) in the vicinity of fatigue cracks. The cyclic indentation tests show a decreased cyclic hardening potential as well as an increased dislocation mobility for the conditions precharged with hydrogen, which correlates to the TEM analysis, revealing courser dislocation cells in the vicinity of the fatigue crack tip. Consequently, the presented results indicate that the hydrogen enhanced localized plasticity (HELP) mechanism leads to accelerated crack growth and change in crack morphology for the materials investigated. In summary, the cyclic indentation tests show a high potential for an analysis of the effects of hydrogen on the local cyclic deformation behavior.

Electromigration and Thermomechanical Fatigue Behavior of Sn0.3Ag0.7Cu Solder Joints

2017 ◽  
Vol 47 (3) ◽  
pp. 1881-1895 ◽  
Author(s):  
Yong Zuo ◽  
Thomas R. Bieler ◽  
Quan Zhou ◽  
Limin Ma ◽  
Fu Guo
Keyword(s):  
Solder Joints ◽  
Fatigue Behavior ◽  
Thermomechanical Fatigue

Thermomechanical Fatigue Behavior of Bare and Coated CMSX-4

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
T. Coppola ◽  
S. Riscifuli ◽  
O. Tassa ◽  
G. Pasquero
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Thermomechanical Fatigue ◽  
Tensile Creep ◽  
Thermal Gradients ◽  
Test Program ◽  
Complete Set ◽  
Comparison Of The Results ◽  
Very High

Highly cooled turbine blades undergo very high thermal gradients during rapid engine idle-max-idle cycling. Traditional isothermal fatigue data are often insufficient for predicting service lives. A complete set of high temperature tests, in the range of 750–1050°C, was performed on single crystal alloy CMSX-4. The test program comprised tensile, creep, low cycle fatigue, and thermomechanical fatigue (TMF) tests. In particular the cycle time for TMF was 3 min, aiming to simulate the real high-power transient conditions in aircraft engines. Clockwise and counterclockwise diamond cycle types were applied on bare and coated specimens to investigate their influence on the fatigue limit. The comparison of the results obtained with the available ones from open literature is discussed.

Impact action on fiber and composite material based on it

2020 ◽  
Vol 6 ◽  
pp. 69-74
Author(s):  
V.V. Kudinov ◽  
◽  
I.K. Krylov ◽  
N.V. Korneeva ◽  
◽  
...  
Keyword(s):  
Composite Material ◽  
Deformation Behavior ◽  
Failure Mechanisms ◽  
Basic Mechanism ◽  
Impact Action ◽  
Uhmwpe Fiber ◽  
Mechanism Of Failure ◽  
First Moment ◽  
The Impact ◽  
Ib Method

The low-velosity impact properties and failure mechanisms of ultra-high molecular weight polyethylene (UHMWPE) fiber (Dyneema®SK-75) and a composite material (CM) based on it with the rigid and flexible matrices were investigated by the “Impact Break” (IB) method. A fundamental difference in deformation behavior and failure mechanisms upon impact on the UHMWPE-fiber and on the CM based on this fiber has been investigated experimentally. It is shown that impact has a little effect on the properties of UHMWPE-fiber, since it is an isotropic material. It has been established that upon impact, the properties of a fiber without a matrix were significantly higher than the properties of CM based on it. Impact action stimulates the interaction between CM components (fibers and matrix). Mechanism of stepwise deformation of anisotropic CM is occurred, which begins from the first moment of impact and ends with the destruction of the CM. A “stairway of deformation” behavior is observed in anisotropic materials. Stepwise deformation is the main form of deformation and the basic mechanism of failure of anisotropic composite materials upon impact.

Development of a High Strength Mg-Zn-Y-Zr Wrought Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 1701-1706
Author(s):  
Rong Shi Chen ◽  
Wei Neng Tang ◽  
Dao Kui Xu ◽  
En Hou Han
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Fatigue Life ◽  
Deformation Behavior ◽  
Fatigue Behavior ◽  
High Strength ◽  
Zn Content ◽  
High Fatigue ◽  
Content Range ◽  
Zr Alloy

The effects of Y addition to the Mg-Zn-Y-Zr alloy on the change of the microstructure and the mechanical properties (with the Y content range of 1 to 3 wt%) have been investigated. It shows that when Zn content is constant (5.65wt%), the alloys with Y content between 1.17 and 1.72wt% nearly reach its highest strength. With the composition near the optimums, the extruded Mg-6%Zn-1%Y-Zr alloy shows high strength and excellent ductility. The deformation behavior of this new alloy at high temperature has also been studied. Moreover, the super-long fatigue behavior of the Mg-6%Zn-1%Y-Zr alloy has also been tested, the results show the alloy with a high fatigue strength of about 85-90MPa in the super-long fatigue life regime of 1×109 cycles.

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