scholarly journals Phase transformation in white etching area in rolling contact fatigue

2018 ◽  
Vol 165 ◽  
pp. 11004
Author(s):  
Yun-Shuai Su ◽  
Shu-Xin Li ◽  
Si-Yuan Lu ◽  
Li-Biao Wan
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Failure Modes ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Optical Microscope ◽  
Rolling Contact ◽  
Transmission Electron ◽  
The Matrix ◽  
White Etching Area

Rolling contact fatigue (RCF) involves microstructural change in the subsurface of contact. The changed microstructure is generally termed as white etching area (WEA) as it appears white under optical microscope when etching in nital solution. WEA has been acknowledged as one of the primary failure modes in RCF since it causes severe local inhomogeneity of microstructure. It was reported that WEA consists of nano ferrites as martensite grains and carbides are significantly refined in the WEA. Some carbides are dissolved. In some cases, an amorphous-like structure was occasionally observed in the WEA, indicating that phase transformation may possibly occur. The WEAs were studied by using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Electron back scattered diffraction (EBSD). The result showed that WEA is dominated with an amorphous phase with martensite, austenite and carbides embedded interior. A distinct interface between the matrix and the WEA was present. In addition to grain refinement down to nanometers, phase transformation including amorphization and austenitization happened in WEAs. The content of austenite was increased from 2% in the matrix to 20% in the WEA. The analysis showed that phase transformation is controlled by plastic deformation mechanism.

scholarly journals Oxygen Induced Phase Transformation in TC21 Alloy with a Lamellar Microstructure

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 163
Author(s):  
Shu Wang ◽  
Yilong Liang ◽  
Hao Sun ◽  
Xin Feng ◽  
Chaowen Huang
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Oxygen Uptake ◽  
Titanium Alloys ◽  
Electron Backscatter Diffraction ◽  
Lamellar Microstructure ◽  
Α Phase ◽  
Transmission Electron ◽  
The Matrix ◽  
Oxygen Ingress

The main objective of the present study was to understand the oxygen ingress in titanium alloys at high temperatures. Investigations reveal that the oxygen diffusion layer (ODL) caused by oxygen ingress significantly affects the mechanical properties of titanium alloys. In the present study, the high-temperature oxygen ingress behavior of TC21 alloy with a lamellar microstructure was investigated. Microstructural characterizations were analyzed through optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). Obtained results demonstrate that oxygen-induced phase transformation not only enhances the precipitation of secondary α-phase (αs) and forms more primary α phase (αp), but also promotes the recrystallization of the ODL. It was found that as the temperature of oxygen uptake increases, the thickness of the ODL initially increases and then decreases. The maximum depth of the ODL was obtained for the oxygen uptake temperature of 960 °C. In addition, a gradient microstructure (αp + β + βtrans)/(αp + βtrans)/(αp + β) was observed in the experiment. Meanwhile, it was also found that the hardness and dislocation density in the ODL is higher than that that of the matrix.

scholarly journals Rolling Wear of Silicon Nitride Bearing Materials

1990 ◽  
Author(s):  
John W. Lucek
Keyword(s):  
Fatigue Life ◽  
Silicon Nitride ◽  
Failure Modes ◽  
Fatigue Testing ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Wear Performance ◽  
Wear Rates ◽  
Bearing Materials

Rolling-contact fatigue test methods were used to measure the wear performance of several silicon nitride materials. Sintered, hot pressed and hot isostatically pressed materials exhibited wear rates ranging over three orders of magnitude. Hot isostatically pressed materials had the lowest wear rates. Despite the disparity in wear performance, all materials tested had useful rolling-contact fatigue lives compared to steel. Fatigue life estimates, failure modes, and rolling wear performance for theses ceramics are compared to M-50 steel. This work highlights the rapid contact stress reductions that occur due to conformal wear in rolling-contact fatigue testing. Candidate bearing materials with unacceptably high wear rates may exhibit useful fatigue lives. Rolling contact bearing materials must possess useful wear and fatigue resistance. Proper performance screening of candidate bearing materials must describe the failure mode, wear rate, and the fatigue life. Guidelines for fatigue testing methods are proposed.

Microstructure and Properties of Cu-Cr-Zr-Ag Alloy

2018 ◽  
Vol 941 ◽  
pp. 1613-1617 ◽  
Author(s):  
Li Jun Peng ◽  
Xu Jun Mi ◽  
Hao Feng Xie ◽  
Yang Yu ◽  
Guo Jie Huang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Phase Transformation ◽  
High Resolution ◽  
Aging Process ◽  
Precipitation Sequence ◽  
Transmission Microscopy ◽  
Transmission Electron ◽  
The Matrix

The Cr precipitation sequence in Cu-Cr-Zr-Ag alloy during the aging process at 450°C could be obtained by Transmission electron microscopy (TEM) and High-resolution transmission microscopy (HRTEM) in the study. The strengthening curve shows a unimodal type and the tensile strength trends to peak when the aged for 4h. The Cr phase transformation of Cu-Cr-Zr-Ag aged at 450°C is supersaturated solid sloution→G.P zones→fcc Cr phase→order fcc Cr phase→bcc Cr phase. The orientation relationship between bcc Cr precipitates and the matrix change from cube-on-cube to NW-OR.

scholarly journals PHASE-TRANSFORMATION DYNAMICS AND CHARACTERIZATION OF PRECIPITATES IN THE Cu-3Ti-3Ni-0.5Si ALLOY

2021 ◽  
Vol 55 (4) ◽  
Author(s):  
Jia Liu ◽  
Jituo Liu ◽  
Xianhui Wang ◽  
Chong Fu ◽  
Yanlong Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electrical Conductivity ◽  
Phase Transformation ◽  
Volume Fraction ◽  
Formation Enthalpy ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
The Matrix ◽  
Diffraction Patterns ◽  
Precipitated Phases

In this paper we investigated the phase-transformation dynamics of the Cu-3Ti-3Ni-0.5Si alloy by applying the Avrami method to phase-transformation dynamics and electrical conductivity based on the relationship between the electrical conductivity and the volume fraction of precipitates in the Cu-3Ti-3Ni-0.5Si alloy. The results corroborated well with the experimental data. The microstructure and precipitated phases were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The analysis of the selected-area electron-diffraction patterns indicated that the precipitates formed in the matrix of the Cu-3Ti-3Ni-0.5Si alloy during aging, correspond to the Ni3Ti, Ni3Si, and Ni2Si phases. According to the values of formation enthalpy and cohesive energy determined by first-principle calculations, the formation of the Ni2Si phase is more favorable compared to the Ni3Si and Ni3Ti phases, and the Ni3Ti exhibits improved structural stability compared to the Ni2Si and Ni3Si phases.

Rolling Contact Fatigue Damage of High-speed Railway Wheels with Upper Bainite

2021 ◽  
pp. 1-25
Author(s):  
Guanzhen Zhang ◽  
Chunpeng Liu ◽  
Si Wu ◽  
Sa Zhao ◽  
Bin Zhang
Keyword(s):  
Electron Microscopy ◽  
High Speed ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
High Speed Railway ◽  
Matrix Microstructure ◽  
Upper Bainite ◽  
The Right ◽  
Railway Wheels

Abstract This work investigates the effect of abnormal microstructure on rolling contact fatigue (RCF) damage of high-speed railway wheels under service and the formation mechanism of abnormal microstructure by optical microscopy, scanning electron microscopy, transmission electron microscopy, nano indentation and laser-induced break down spectroscopy. Results show that there are large amounts of upper bainite in the wheel tread, which destroyed the uniformity of the microstructures of the wheel matrix. The bainite is composed of ferrite with high density of dislocations and short bar-shaped cementite. The bainite exhibited higher hardness and elasticity but lower plasticity than the matrix microstructure. The incongruity of plastic deformation between upper bainite and matrix microstructures will lead to stress concentration at boundary of the microstructures, thus accelerating the RCF crack initiation and propagation. The formation of upper bainite is caused by carbon segregation. Segregation of carbon element will make the continuous cooling transformation (CCT) curve shift to the right significantly, thus increasing the probability of bainite transformation in segregation zone at higher cooling rate. Therefore, large amounts of upper bainite were formed at wheel tread.

Experimental Study of the Effects of Surface Defects on Rolling Contact Fatigue Behavior

2007 ◽  
Vol 353-358 ◽  
pp. 254-257
Author(s):  
Guan Chen ◽  
Hong Ping Zhao ◽  
Shao Hua Ji ◽  
Xi Qiao Feng ◽  
Hui Ji Shi
Keyword(s):  
Failure Modes ◽  
Surface Defects ◽  
Fatigue Behavior ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Surface Cracks ◽  
Hardness Tester ◽  
Rolling Surface ◽  
Contact Fatigue Resistance

Rolling contact fatigue (RCF) cracks initiated from surface and subsurface defects are typical failure modes of bearing systems. In this paper, the effects of surface defects on RCF behavior of M50NiL and M50 steels were studied experimentally. Artificial dents were introduced on the rolling surface by using Rockwell hardness tester. The influences of dent shape and dent shoulders were examined by thrust-type RCF tests. Surface cracks initiation, propagation and spalling were monitored by scanning electron microscope (SEM) observation. The results showed that artificial dents reduce RCF lives of M50NiL and M50 steels with mineral oil lubrication. The fatigue failure initiates at the surface defect with the effects of dent shape and dent shoulder. M50NiL steel has higher contact fatigue resistance than M50. The features of surface and sub-surface cracks propagation during RCF tests were also observed.

S1160104 White Etching Area due to Rolling Contact Fatigue

2015 ◽  
Vol 2015 (0) ◽  
pp. _S1160104--_S1160104-
Author(s):  
Susumu MIYAKAWA ◽  
Yoshirou NISHIMURA ◽  
Satoru NAKAZAWA ◽  
Nobuhiro SHIOYA
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
White Etching Area

TEM Investigation of Butterfly and White Etching Area Formed During Rolling Contact Fatigue

2012 ◽  
Vol 18 (S2) ◽  
pp. 1778-1779
Author(s):  
V. Bedekar ◽  
R. Hyde ◽  
R. Shivpuri
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
White Etching Area

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

A Unified Model for Rolling Contact Life Prediction

1982 ◽  
Vol 104 (3) ◽  
pp. 336-346 ◽  
Author(s):  
T. E. Tallian
Keyword(s):  
Failure Modes ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Unified Model ◽  
Rolling Contact ◽  
Local Plastic Strain ◽  
Contact Fatigue Life ◽  
Engineering Models ◽  
Contact Life ◽  
Life Distributions

Systematizing a ten-year development of engineering models for the prediction of rolling contact fatigue life distributions, a unified model is presented. Based on a crack growth rate relationship with local plastic strain and ductility, and on defect populations in the contact material and at the contact surfaces, the model predicts life of a defect, then generalizes to rolling body life. Subsurface and surface failure modes are considered; the effects of material matrix, defect severity, stress condition, surface traction, and asperity interactions are encompassed. The model includes crack initiation and propagation terms and allows for a finite minimum life. The model specializes to Lundberg-Palmgren theory.

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