High Cycle Fatigue Behavior of Cold Forging Die Steel

2009 ◽  
Vol 417-418 ◽  
pp. 225-228 ◽  
Author(s):  
Ryuichiro Ebara ◽  
R. Nohara ◽  
Rintaro Ueji ◽  
A. Ogura ◽  
Y. Ishihara ◽  
...  
Keyword(s):  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cold Forging ◽  
Propagation Mode ◽  
Cycle Fatigue ◽  
Die Steel ◽  
Initiation And Propagation ◽  
Number Of Cycles ◽  
Forging Die

High cycle fatigue behavior of the representative cold forging die steel, YXR3 with Rockwell C scale hardness number of 60.0 is investigated. Axial fatigue strength of plane and notched bar specimens with stress concentration factor, Kt of 1.5, 2.0 and 2.5 is presented. The emphasis is placed upon the subsurface crack initiation observed on notched specimens failed at number of cycles over than 106 cycles. Crack initiation and propagation mode of cold forging die steel is discussed with respect to fracture surface morphology.

High Cycle Fatigue Behavior of Recycled Additive Manufactured Electron Beam Melted Titanium Ti6Al4V

2020 ◽  
Author(s):  
Melody Mojib ◽  
Rishi Pahuja ◽  
M. Ramulu ◽  
Dwayne Arola
Keyword(s):  
Electron Beam ◽  
Fatigue Life ◽  
Rough Surface ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
High Strength ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Initiation And Propagation ◽  
Powder Recycling

Abstract Metal Additive Manufacturing (AM) has become a popular method for producing complex and unique geometries, especially gaining traction in the aerospace and medical industries. With the increase in adoption of AM and the high cost of powder, it is critical to understand the effects of powder recycling on part performance to move towards material qualification and certification of affordable printed components. Due to the limitations of the Electron Beam Melting (EBM) process, current as-printed components are susceptible to failure at limits far below wrought metals and further understanding of the material properties and fatigue life is required. In this study, a high strength Titanium alloy, Ti-6Al-4V, is recycled over time and used to print fatigue specimens using the EBM process. Uniaxial High Cycle Fatigue tests have been performed on as-printed and polished cylindrical specimens and the locations of crack initiation and propagation have been determined through the use of a scanning electron microscope. This investigation has shown that the rough surface exterior is far more detrimental to performance life than the powder degradation occurring due to powder reuse. In addition, the effects of the rough surface exterior as a stress concentration is evaluated using the Arola-Ramulu. The following is a preliminary study of the effects powder recycling and surface treatments on EBM Ti-6Al4V fatigue life.

scholarly journals Recent Advances in Very High Cycle Fatigue Behavior of Metals and Alloys—A Review

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1200
Author(s):  
Ashutosh Sharma ◽  
Min Chul Oh ◽  
Byungmin Ahn
Keyword(s):  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Simulation Studies ◽  
Cycle Fatigue ◽  
Future Directions ◽  
Very High Cycle Fatigue ◽  
Ultrasonic Fatigue ◽  
Very High

We reviewed the research and developments in the field of fatigue failure, focusing on very-high cycle fatigue (VHCF) of metals, alloys, and steels. We also discussed ultrasonic fatigue testing, historical relevance, major testing principles, and equipment. The VHCF behavior of Al, Mg, Ni, Ti, and various types of steels were analyzed. Furthermore, we highlighted the major defects, crack initiation sites, fatigue models, and simulation studies to understand the crack development in VHCF regimes. Finally, we reviewed the details regarding various issues and challenges in the field of VHCF for engineering metals and identified future directions in this area.

Effect of the Rheocasting Process and of the SLS Layer on the Fatigue Behavior of 357 Aluminum Alloy

2014 ◽  
Vol 217-218 ◽  
pp. 227-234 ◽  
Author(s):  
Alain Abou Antoun ◽  
Myriam Brochu ◽  
Heinrich Möller
Keyword(s):  
Aluminum Alloy ◽  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Initiation Mechanism ◽  
Liquid Segregation ◽  
Surface Liquid ◽  
Effect Of Surface

Two objectives were targeted: 1) compare the high cycle fatigue behavior of rheocast aluminum alloy 357 prepared by the swirl enthalpy equilibration device (SEED) and by the Council for Scientific and Industrial Research (CSIR) process, and 2) study the effect of surface liquid segregation (SLS) on the fatigue behavior of the CSIR material. Rectangular hourglass specimens machined from rheocast plates were tested at four stress amplitudes in axial fatigue with a stress ratio of R = -1 and a frequency of 20 Hz. Results obtained for SLS free specimens show that the SEED and the CSIR processes produce rheocast materials with comparable high cycle fatigue properties, 115 MPa at 107 cycles. In order to study the influence of surface liquid segregation, slightly polished specimens with a remaining SLS of nearly 750 microns thick were also tested. According to the results, the SLS reduces the average fatigue strength by approximately 5% (110 MPa vs. 115 MPa at 107 cycles). For SLS free specimens, the fatigue crack initiated at shrinkage cavities, oxide films or in the alpha globules. On the other hand, for specimens with SLS, no crack initiation in the alpha globules was observed. The main crack initiation mechanism was identified to be a deformation incompatibility between regions characterized by higher silicon content compared to nominal eutectic regions. The originality of the work is provided by the rigorous comparative analysis of the fatigue performance of components produced in two different rheocasting facilities, but tested in a single laboratory. It is also the first fundamental research published on the mechanical effect of surface liquid segregation. It confirms that SLS should be removed in critical areas in order to optimize the fatigue resistance of rheocast components.

scholarly journals Effect of LCF Pre-Damage on Very High Cycle Fatigue Behavior of TC21 Titanium Alloy

2017 ◽  
Author(s):  
Nie Baohua ◽  
Zhao Zihua ◽  
Ouyang Yongzhong ◽  
Chen Dongchu ◽  
Chen Hong ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Mechanism Analysis ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High

The effect of low cycle fatigue (LCF) pre-damage on the subsequent very high cycle fatigue (VHCF) behavior is investigated in TC21 titanium alloy. LCF pre-damage is applied under 1.8% strain amplitude up to various fractions of the expected life and subsequent VHCF properties are determined using ultrasonic fatigue tests. Results show that 5% of LCF pre-damage insignificantly affects the VHCF limit due to the absent of pre-crack, but decreases the subsequent fatigue crack initiation life estimated by Pairs’ law. Pre-cracks introduced by 10% and 20% of LCF pre-damage significantly reduce the subsequent VHCF limits. The crack initiation site shifts from subsurface-induced fracture for undamaged and 5% of LCF pre-damage specimens to surface pre-crack for 10% and 20% of LCF pre-damage specimens in very high cycle region. The fracture mechanism analysis indicate that LCF pre-crack will re-start to propagate under subsequently low stress amplitude when stress intensity factor of pre-crack is larger than its threshold. Furthermore, the predicted fatigue limits based on EI Haddad model for the LCF pre-damage specimens well agree with the experimental results.

scholarly journals Interactions between geometrical defects and microstructure during high cycle fatigue of polycrystalline aluminium with different grain sizes

2018 ◽  
Vol 165 ◽  
pp. 14004
Author(s):  
Benoît Bracquart ◽  
Charles Mareau ◽  
Nicolas Saintier ◽  
Franck Morel
Keyword(s):  
Grain Size ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Cycle Fatigue ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Geometrical Defects

In this work, the influence of the geometrical defect size on the high cycle fatigue behavior of polycrystalline aluminium with different grain sizes is investigated, to better understand the role of internal length scales. Two sizes of grains and defect are used: 100 μm and 1000 μm, the grain size being controlled with thermomechanical treatments. Fully reversed stress-controlled fatigue tests are then carried out. According to fatigue test results, surface crack initiation is delayed when the grain size is reduced, while an approximation of the fatigue limit shows that it is not much influenced by the average grain size. The relative defect diameter (compared to the grain size) seems to be the leading parameter influencing fatigue crack initiation from a defect. Finally, Electron BackScattered Diffraction (EBSD) maps are collected for specimens with large grains and small defects. Fatigue crack initiation from a defect is found to be strongly impacted by the crystallographic orientation of the surrounding grain, crack initiation preferably occurring in crystals being favorably oriented for plastic slip.

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