Fatigue Properties of a Low-Alloy Steel with a Nano-Structured Surface Layer Obtained by Severe Mechanical Treatments

2013 ◽  
Vol 577-578 ◽  
pp. 469-472 ◽  
Author(s):  
Seyyed Mostafa Hassani-Gangaraj ◽  
A. Moridi ◽  
Mario Guagliano
Keyword(s):  
Surface Layer ◽  
Alloy Steel ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Xrd Analysis ◽  
Processing Parameters ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Low Alloy Steel ◽  
Structured Surface

Recent development in mechanical technologies and processes have shown that by performing traditional mechanical treatments with unusual and severe parameters it is possible to obtain metal surfaces characterized by grain size with dimension in the order of 50-100 nm. This confers peculiar and superior properties to the surface layer of material. Since the surface is the usual point of fatigue crack initiation it is expected that the parts treated this way show a better fatigue behavior with respect to the coarse grain materials, even if treated with conventional mechanical treatments. This work explores any opportunities to obtain nano-structured surface layers by means of two popular mechanical treatments, shot peening and deep rolling. To this end particularly severe processing parameters are applied on a low alloy steel fatigue test specimens. The treated surface is characterized by means of optical Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) analysis of residual stress and roughness measurements. In the end a series of fatigue tests on smooth specimens severely treated, conventionally treated and not treated were executed. The results show the potential benefits of severe mechanical treatments and were interpreted in the light of peculiar effects of these novel treatments on the characteristics of the treated surfaces.

Effect of Plasma Nitriding on Ultra-High Cycle Fatigue Behaviors of Ti-6Al-4V

2011 ◽  
Vol 295-297 ◽  
pp. 2386-2389 ◽  
Author(s):  
Ren Hui Tian ◽  
Qiao Lin Ouyang ◽  
Qing Yuan Wang
Keyword(s):  
High Cycle Fatigue ◽  
Plasma Nitriding ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Ultrasonic Fatigue ◽  
Ultra High Cycle Fatigue ◽  
Stress Ratios

In order to investigate the effect of plasma nitriding treatment on fatigue behavior of titanium alloys, very high cycle fatigue tests were carried out for Ti-6Al-4V alloy using an ultrasonic fatigue machine under load control conditions for stress ratios of R=-1 at frequency of ƒ=20KHz. Experiment results showed that plasma nitriding treatment played the principal role in the internal fatigue crack initiation. More importantly, plasma nitriding treatment had a detrimental effect on fatigue properties of the investigated Ti-6Al-4V alloy, and the fatigue strength of material after plasma nitriding treatment appeared to be significantly reduced about 17% over the untreated material.

Severe Shot Peening to Get a Nano-Structured Surface Layer in Low-Alloy Steel

2017 ◽  
Vol 06 (05) ◽  
Author(s):  
Colombo C ◽  
Maria Elvira S ◽  
Fernandez I ◽  
Juan Gonzalez Suarez
Keyword(s):  
Surface Layer ◽  
Alloy Steel ◽  
Shot Peening ◽  
Low Alloy Steel ◽  
Structured Surface ◽  
Severe Shot Peening

Experimental and Numerical Analysis of Fatigue Properties Improvement in a Titanium Alloy by Shot Peening

2010 ◽  
Author(s):  
Sara Bagherifard ◽  
Marco Giglio ◽  
Lorenzo Giudici ◽  
Mario Guagliano
Keyword(s):  
Titanium Alloy ◽  
Surface Layer ◽  
Shot Peening ◽  
Fatigue Behavior ◽  
Quantitative Description ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
X Ray Diffraction ◽  
Residual Stress Field ◽  
Good Correspondence

Shot peening (SP) is a mechanical surface treatment commonly performed to improve the fatigue behavior through creation of compressive residual stresses close to surface and work hardening of the surface material. Notwithstanding wide application of shot peening in the industrial environment, the determination of optimal peening condition for Ti alloys is still more an art than a science, taking into account that there is not a well established method to choose the process parameters in order to enhance the fatigue behavior. In this paper a comprehensive numerical and experimental study is presented aimed at finding the optimized peening conditions based on characterization of surface layer of material after multiple impacts. The numerical simulations provide a quantitative description of shot peening effects in terms of residual stress field and thickness of work-hardened surface layer. Comparison with numerical results, obtained by means of X-ray diffraction (XRD), shows a very good correspondence. Finally the results of experimental bending fatigue tests, performed on shot peened specimens by means of Rumul Cracktronics machine, confirm that shot peening significantly increases the fatigue strength of the considered Titanium alloy.

scholarly journals Effects of thermomechanical history and environment on the fatigue behavior of (β)-Ti-Nb implant alloys

2018 ◽  
Vol 165 ◽  
pp. 06001 ◽  
Author(s):  
André Reck ◽  
Stefan Pilz ◽  
Ulrich Thormann ◽  
Volker Alt ◽  
Annett Gebert ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Cyclic Loading ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Grain Structure ◽  
Fatigue Properties ◽  
Β Phase ◽  
Α Phase ◽  
Nb Content ◽  
Implant Alloys

This study examined the fatigue properties of a newly developed cast and thermomechanical processed (β)-Ti-40Nb alloy for a possible application as biomedical alloy due to exceptional low Young’s modulus (64-73 GPa), high corrosion resistance and ductility (20-26%). Focusing on the influence of two microstructural states with fully recrystallized β-grain structure as well as an aged condition with nanometer-sized ω-precipitates, tension-compression fatigue tests (R=-1) were carried out under lab-air and showed significant differences depending on the β-phase stability under cyclic loading. Present ω- precipitates stabilized the β-phase against martensitic α’’ phase transformations leading to an increased fatigue limit of 288 MPa compared to the recrystallized state (225 MPa), where mechanical polishing and subsequent cyclic loading led to formation of α’’-phase due to the metastability of the β-phase. Additional studied commercially available (β)-Ti-45Nb alloy revealed slightly higher fatigue strength (300 MPa) and suggest a change in the dominating cyclic deformation mechanisms according to the sensitive dependence on the Nb-content. Further tests in simulated body fluid (SBF) at 37°C showed no decrease in fatigue strength due to the effect of corrosion and prove the excellent corrosion fatigue resistance of this alloy type under given test conditions.

scholarly journals Effect of sliding contact on fatigue properties of low alloy steel

2019 ◽  
Vol 85 (873) ◽  
pp. 18-00401-18-00401
Author(s):  
Yuiko SAKAYAMA ◽  
Takanori KATO ◽  
Taizo MAKINO ◽  
Miyuki YAMAMOTO
Keyword(s):  
Alloy Steel ◽  
Sliding Contact ◽  
Fatigue Properties ◽  
Low Alloy Steel

Effects of Water Jet Peening and Hardening Treatment on Fatigue Properties of SCr420

2009 ◽  
Author(s):  
Akira Shimamoto ◽  
Ryo Kubota ◽  
Sung-mo Yang ◽  
Dae-kue Choi ◽  
Weiping Jia
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Water Jet ◽  
Fatigue Properties ◽  
In Situ Observation ◽  
Axial Tensile ◽  
High Pressure Water Jet

An experimental study of high pressure water jet peening treatment on chromium steal SCr420 H3V2L2 is conducted to study the effects of cavitation impacts of high-speed water on fatigue crack initiation and propagation of notched specimens. There are six different kinds of specimens. First three kinds are treated with; only annealing, only water quenching, and only oil quenching. Other three kinds are treated with above heat treatment and water jet peening, respectively. An axial tensile fatigue tests’ condition is 260MPa maximum stress amplitude, 0 stress ratio and 10Hz frequency, while in-situ observation by SEM is employed. Although fatigue life of the specimens with annealing and water jet peening is shorter than that of only annealing, fatigue life of water and oil quenching with water jet peening specimens is obviously longer than those without water jet peening treatment. Water jet peening has increased residual stress inside the specimens on the latter case and raised their fatigue strength. In-situ observation on the crack tips approves above analysis.

The Processing and Fatigue Characterization of TiNi and Ti-6Al-4V Porous Materials

2011 ◽  
Vol 493-494 ◽  
pp. 930-935 ◽  
Author(s):  
Emin Erkan Aşik ◽  
Gül Ipek Nakaş ◽  
Şakir Bor
Keyword(s):  
Titanium Alloys ◽  
Endurance Limit ◽  
Fatigue Behavior ◽  
Porous Titanium ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Compression Tests ◽  
Limit Values ◽  
Porous Ti ◽  
Structural Applications

Porous titanium alloys have been extensively studied in biomedical applications due to their elastic moduli similar to that of bone compared to other implant materials. Accordingly, TiNi and Ti-6Al-4V foams have been widely characterized in terms of their various mechanical properties; however, their fatigue properties have not been well studied, even though, it has a vital importance in structural applications such as medical implants. In this study, porous titanium alloys were processed via sintering at 1200 °C for 2 hours employing Mg space holder technique. TiNi and Ti-6Al-4V alloys with a porosity of 49 and 51 vol.%, respectively, were mechanically characterized by monotonic and cyclic compression tests. The compressive strength was determined to be 148 MPa for TiNi foams whereas 172 MPa for Ti-6Al-4V foams with homogenously distributed pores having diameters in the range of 250-600 µm. Endurance limit values were determined relative to the yield strength of each porous alloy in order to enable the comparison of fatigue behavior. The fatigue tests applied with a frequency of 5 Hz and a constant stress ratio (σmin/σmax) of 0.1 have revealed that porous TiNi alloys have an endurance limit of approximately 0.6 σy whereas porous Ti-6Al-4V alloys have an endurance limit of approximately 0.75 σy. The differences and similarities in the microstructure and their effect on mechanical behavior of the two alloys were also studied by employing scanning electron microscope (SEM).

Influence of Ni5Zr Particles on Fatigue Property of Ni3Al Alloy

1994 ◽  
Vol 364 ◽  
Author(s):  
Gang Li ◽  
Jian-Ting Guo ◽  
Zhong-Guang Wang
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Fatigue Property ◽  
Fatigue Tests ◽  
Al Alloy ◽  
Second Phase ◽  
Cycle Fatigue ◽  
Second Phase Particles ◽  
Minimum Stress

AbstractIn this investigation, the influence of second phase particles on high cycle fatigue behavior of Ni3Al alloy is studied. A single phase Ni3Al-B alloy and a Ni3Al-B/Zr alloy with a few second phase particles (Ni5Zr) at the grain boundaries are selected for investigation. High cycle fatigue tests at room temperature with R (minimum stress/maximum stress) 0.1 are conducted in air and at 30 Hz. The results show that the second phase particles are detrimental to high cycle fatigue resistance. It may be explained in terms of the second phase particles promoting fatigue crack initiation. The characteristics of fracture surfaces are examined by Scanning Electron Microscopy (SEM).

scholarly journals Effect of UV Ageing on the fatigue life of bulk polyethylene

2018 ◽  
Vol 165 ◽  
pp. 08002 ◽  
Author(s):  
Hamza Lamnii ◽  
Moussa Nait-Abdelaziz ◽  
Georges Ayoub ◽  
Jean-Michel Gloaguen ◽  
Ulrich Maschke ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Uv Irradiation ◽  
Chemical Structure ◽  
Fatigue Behavior ◽  
Crystalline Polymer ◽  
Fatigue Loading ◽  
Chain Scission ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Irradiation Effect

Polymers operating in various weathering conditions must be assessed for lifetime performance. Particularly, ultraviolet (UV) radiations alters the chemical structure and therefore affect the mechanical and fatigue properties. The UV irradiation alters the polymer chemical structure, which results into a degradation of the mechanical and fatigue behavior of the polymer. The polymer properties degradation due to UV irradiation is the result of a competitive process of chain scission versus post-crosslinking. Although few studied investigated the effect of UV irradiation on the mechanical behaviour of thermoplastics, fewer examined the UV irradiation effect on the fatigue life of polymers. This study focuses on investigating the effect of UV irradiation on the fatigue properties of bulk semi-crystalline polymer; the low density Polyethylene (LDPE). Tensile specimens were exposed to different dose values of UV irradiation then subjected to fatigue loading. The fatigue tests were achieved under constant stress amplitude at a frequency of 1Hz. The results show an important decrease of the fatigue limit with increasing absorbed UV irradiation dose.

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