High Cycle Fatigue Properties and Failure Mode in Ni-Cr-Mo Steel Tempered at Low Temperature

2008 ◽  
Vol 385-387 ◽  
pp. 185-188 ◽  
Author(s):  
Yu Mochizuki ◽  
Masaki Nakajima ◽  
Toshihiro Shimizu
Keyword(s):  
Low Temperature ◽  
Failure Mode ◽  
High Cycle Fatigue ◽  
Axial Loading ◽  
High Strength ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Statistics Of Extremes ◽  
Rotating Bending

High cycle fatigue properties and failure mode in high strength steel tempered at low temperature were studied. The material used was Ni-Cr-Mo steel, JIS SNCM439, which was tempered at 453 K. After heat treatment, round bar specimens with hourglass shape were machined. Fatigue tests were performed using two kinds of specimens with two surface conditions, i.e., as-ground specimen and buff-finished specimen. Tests were conducted under rotating bending and axial loading. Under rotating bending, in as-ground specimens, fatigue failure took place in high cycle region above 107 cycles and failure mode was surface-related. On the other hand, buff-finished specimens exhibited the step-wise S-N curve, i.e., the subsurface fracture with a fish-eye was observed. However, under axial loading, even in buff-finished specimens the subsurface fracture didn’t occur due to small nonmetallic inclusions. Based on the results, the fatigue limit was estimated by the statistics of extremes. The prediction gave the conservative values.

Fatigue Test of Al-3%Ti Using Axial Loading Testing Machine for MEMS Materials

2005 ◽  
Author(s):  
Jun-Hyub Park ◽  
Hyeon Chang Choi ◽  
Chang Seung Lee ◽  
Sung-Hoon Choa ◽  
Man Sik Myung ◽  
...  
Keyword(s):  
Thin Film ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Testing Machine ◽  
Axial Loading ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Mems Switch

This paper presents high cycle fatigue properties of an Al-3%Ti thin film, used in a RF (radio-frequency) MEMS switch for a mobile phone. The thickness and width of the thin film of specimen are 1.1 μm and 480 μm, respectively. Tensile tests of five specimens are performed, from which the ultimate strength is found to be 144MPa. High cycle fatigue tests of six specimens are also performed, from which the fatigue strength coefficient and the fatigue strength exponent are found to be 336MPa and −0.1514, respectively.

A Study on Very High Cycle Fatigue Properties of Low Flammability Magnesium Alloy in Rotating Bending and Axial Loading

2015 ◽  
Vol 782 ◽  
pp. 27-41 ◽  
Author(s):  
Tatsuo Sakai ◽  
Shoichi Kikuchi ◽  
Yuki Nakamura ◽  
Noriyuki Ninomiya
Keyword(s):  
Magnesium Alloy ◽  
High Cycle Fatigue ◽  
Axial Loading ◽  
Fatigue Properties ◽  
Stress Intensity Factor Range ◽  
Cycle Fatigue ◽  
Fracture Surfaces ◽  
Very High Cycle Fatigue ◽  
Rotating Bending ◽  
Very High

In order to use a low flammability magnesium alloy as structural components, very high cycle fatigue properties of this alloy (AMCa602) were investigated. S-N properties obtained in both rotating bending and axial loading were compared with each other. It was found that S-N curve in the axial loading appeared a little lower than that in the rotating bending due to the differences of stress distributions and critical volumes for both loading types. Moreover, the statistical aspect on the fatigue property was analyzed as P-S-N characteristics in the rotating bending. After fatigue tests, fracture surfaces of failed specimens were observed by means of a scanning electron microscope (SEM) and the microstructures at the crack initiation site and the propagation path were also observed by combining FIB technique and EBSD analysis. Thus, it was found that some specimens failed from surface inclusions and their fatigue lives were lower in comparison to those of the specimens without surface inclusions. In addition, the fracture surfaces of this alloy revealed very rough in the usual life region, whereas a characteristic smooth area was observed on the fracture surfaces of specimens failed in the surface inclusion-initiated fracture and in very high cycle regime. A stress intensity factor range at the front of the smooth area (ΔKsmooth) tended to a definite value so that the fracture mechanism of this alloy was governed by a concept of ΔK.

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.

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.

High Cycle Fatigue Properties of Multi-Directionally Forged Commercial Purity Grade 2 Ti Plate

2018 ◽  
Vol 916 ◽  
pp. 166-169
Author(s):  
Ilhamdi ◽  
Toshifumi Kakiuchi ◽  
Hiromi Miura ◽  
Yoshihiko Uematsu
Keyword(s):  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Pure Titanium ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Commercially Pure Titanium ◽  
Cycle Fatigue ◽  
Subsurface Crack ◽  
Initiation Mechanism ◽  
Fish Eye

Tension-tension fatigue tests were conducted using ultrafine-grained commercially pure Titanium (Ti) plates fabricated by multi-directional forging (MDFing). The MDFed pure Ti plates with the thickness of 1 mm were developed aiming at dental implant application. The fatigue properties of MDFed pure Ti plates were superior to those of the conventional rolled pure Ti plates. The higher fatigue strengths in MDFed plates could be attributed to the much finer grains evolved by MDFing. Fatigue crack initiated from specimen surface, when number of cycles to failure was shorter than 106 cycles. In the high cycle fatigue (HCF) region, however, subsurface crack initiation with typical fish-eye feature was recognized in the MDFed pure Ti plate in spite of the thin thickness. Fractographic analyses revealed that no inclusion existed at the center of fish-eye. The subsurface crack initiation mechanism could be related to the inhomogeneity of microstructure with some coarse grains in the inner part of the plate.

Study on Tensile and High Cycle Fatigue Properties of TiC Particle Reinforced Titanium Matrix Composite

2007 ◽  
Vol 546-549 ◽  
pp. 1535-1540 ◽  
Author(s):  
Li Ying Zeng ◽  
Yong Qing Zhao ◽  
Xiao Nan Mao ◽  
Yun Lian Qi
Keyword(s):  
Matrix Composite ◽  
High Cycle Fatigue ◽  
Load Ratio ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Titanium Matrix ◽  
Titanium Matrix Composite ◽  
Tic Particle ◽  
Hcf Strength

Tensile and high cycle fatigue (HCF) property for TiC particle reinforced titanium matrix composite has been studied in this paper. The results indicated that the composite possessed favorite comprehensive properties. The tensile properties for the composite are superior to that of the common high temperature titanium alloys, e.g. IMI834, Ti-1100. Smooth axial fatigue tests were taken at a frequency of 76Hz with a load ratio R of 0.06 and –1, respectively. And HCF strength for the composite at ambient temperature is 595MPa and 494MPa, respectively.

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