Microstructural Analysis and Wear Behavior of Cryogenically Treated Ti-6Al-4V Alloy

Mean stress on fatigue strength of Ti-35Nb-7Zr-5Ta, used in the manufacture of orthopedic prostheses, was evaluates. Samples of Ti-35Nb-7Zr-5Ta were pressureless, sintered and tested using microhardness (Vickers) and four point bending fatigue conditions. Characterization was carried out using optical microscopy, scanning electron microscopy, EDS analysis, oxygen analysis and density. The microstructural analysis shows low densification after sintering (almost 86% of theoretical) and some precipitates of α phase and presumably ω phase at the grain and grain boundaries. The bending fatigue resistance limit reached (Se (106) = 90 MPa), due to, presumably, the influence of the medium-high porosity, α phase precipitates at grain boundaries as well as the high oxygen content in the material after sintering (0.96 %). In this case, Kwofie model best explains the influence of mean stress on fatigue strength of this alloy.

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Crystallographic and morphological relationships between β phase and the Widmanstätten and allotriomorphic α phase at special β grain boundaries in an α/β titanium alloy

Acta Materialia ◽

10.1016/j.actamat.2007.08.029 ◽

2007 ◽

Vol 55 (20) ◽

pp. 6765-6778 ◽

Cited By ~ 107

Author(s):

D. Bhattacharyya ◽

G.B. Viswanathan ◽

Hamish L. Fraser

Keyword(s):

Titanium Alloy ◽

Grain Boundaries ◽

Β Phase ◽

Α Phase

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Microstructural Analysis of Thermite Welds

2010 Joint Rail Conference, Volume 1 ◽

10.1115/jrc2010-36086 ◽

2010 ◽

Author(s):

Konstantin V. Redkin ◽

C. Isaac Garcia ◽

Anthony J. DeArdo ◽

Daniel Gutscher ◽

Semih Kalay

Keyword(s):

Grain Boundaries ◽

Prior Austenite ◽

Wear Behavior ◽

Microstructural Analysis ◽

Cost Effective ◽

Structural Factors ◽

Austenite Grain ◽

Processing Factors ◽

Performance Behavior ◽

Prior Austenite Grain

Thermite welding is a simple and cost-effective process widely used in the field for rail repair and joining. Despite the well-accepted use of this technology, there is a major concern regarding the soundness of the weldments which are often found to be very sensitive to wear and cracking. In order to gain a better understanding of the structural factors that contribute to the performance behavior of thermite welds, systematic microstructural analyses of a series of welds was conducted. Of particular interest in this study was to carefully examine and compare the microstructure of the weld metal, heat affected zone (HAZ) and base metal of a series of thermite welded samples with different carbon content. The results of this work revealed the presence of proeutectoid cementite along the prior austenite grain boundaries at the three locations examined. In addition, microhardness evaluation of the welds revealed that substantial softening takes place in the HAZ, independent of the chemical composition of the rails or weld processing conditions. The presence of proeutectoid cementite along the prior austenite grain boundaries and the softening that takes place in the HAZ are two of the structural factors most likely responsible for the lower than expected wear behavior observed in welded or repaired rail steels. This paper will present and discuss the microstructural and processing factors associated with the formation of proeutectoid cementite and the causes leading to the observed softening.

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Phase Transformation and Microstructure Evolution in Near-β Ti-7333 Titanium Alloy during Aging

Materials Science Forum ◽

10.4028/www.scientific.net/msf.747-748.904 ◽

2013 ◽

Vol 747-748 ◽

pp. 904-911 ◽

Cited By ~ 1

Author(s):

Qiong Hui ◽

Xiang Yi Xue ◽

Hong Chao Kou ◽

Min Jie Lai ◽

Bin Tang ◽

...

Keyword(s):

Titanium Alloy ◽

Phase Transformation ◽

Grain Boundaries ◽

Parent Phase ◽

Solution Treatment ◽

Ageing Treatment ◽

Β Phase ◽

Α Phase ◽

Nucleation Sites ◽

Higher Temperature

A newly near-β titanium alloy Ti-7Mo-3Cr-3Nb-3Al (Ti-7333) was subjected to β phase solution treatment and ageing in the present work. The characteristics of α phase transformation in ageing treatment were studied. Results show that isothermal aging at a low temperature (350) will result in lots of ω particles with small size homogeneously distributing in the parent phase. These ω particles can act as nucleation sites for α phase and lead to the uniform precipitation of fine α phase within the β grain after further ageing treatment. However, when ageing at a higher temperature, the α phase tends to precipitate direct from the β matrix and the morphology of α phase is determined by the temperature and period of ageing treatment. After aging at 550 for 5min, acicular α phase precipitates in the β grains as well as along β grain boundaries and the size and quantity of α phase increase with the holding time. Note that Ti-7333 alloy has a quick ageing response. When aging at 700 for 1h, coarser α laths precipitate both on the grain boundary and within the grain. Increase the ageing temperature to 800, α phase precipitates within the β grain as short rod-like morphology. It is suggested that the driving force for α phase nucleation and the amount of defects in the intragranular decrease with the increasing of temperature, leading to the grain boundaries become the prior nucleation sites. Substantial α phase precipitate-free regions adjacent to β grain boundaries remained after ageing at 700 for 1h due to the rejection of β-stabilizer from coarse α lath on β grain boundaries. Aging at 800 for 1h resulted in pronounced continuous α-films along β grain boundaries.

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Microstructural Analysis of Thermite Welds

ASME 2010 Rail Transportation Division Fall Technical Conference ◽

10.1115/rtdf2010-42001 ◽

2010 ◽

Cited By ~ 1

Author(s):

Konstantin V. Redkin ◽

C. Isaac Garcia ◽

Anthony J. DeArdo

Keyword(s):

Grain Boundaries ◽

Prior Austenite ◽

Wear Behavior ◽

Microstructural Analysis ◽

Cost Effective ◽

Structural Factors ◽

Austenite Grain ◽

Processing Factors ◽

Performance Behavior ◽

Prior Austenite Grain

Thermite welding is a simple and cost-effective process widely used in the field for rail repair and joining. Despite the well-accepted use of this technology, there is a major concern regarding the soundness of the weldments which are often found to be very sensitive to wear and cracking. In order to gain a better understanding of the structural factors that contribute to the performance behavior of thermite welds, systematic microstructural analyses of a series of welds was conducted. Of particular interest in this study was to carefully examine and compare the microstructure of the weld metal, heat affected zone (HAZ) and base metal of a series of thermite welded samples with different carbon content. The results of this work revealed the presence of proeutectoid cementite along the prior austenite grain boundaries at the three locations examined. In addition, microhardness evaluation of the welds revealed that substantial softening takes place in the HAZ, independent of the chemical composition of the rails or weld processing conditions. The presence of proeutectoid cementite along the prior austenite grain boundaries and the softening that takes place in the HAZ are two of the structural factors most likely responsible for the lower than expected wear behavior observed in welded or repaired rail steels. This paper will present and discuss the microstructural and processing factors associated with the formation of proeutectoid cementite and the causes leading to the observed softening.

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Effect of a Deep Cryogenic Treatment on Wear and Microstructure of a 6101 Aluminum Alloy

Advances in Materials Science and Engineering ◽

10.1155/2016/1582490 ◽

2016 ◽

Vol 2016 ◽

pp. 1-12 ◽

Cited By ~ 10

Author(s):

Volker Franco Steier ◽

Edgar Sobral Ashiuchi ◽

Lutz Reißig ◽

José Alexander Araújo

Keyword(s):

Wear Resistance ◽

Aluminum Alloy ◽

Wear Behavior ◽

Cryogenic Treatment ◽

Microstructural Analysis ◽

Deep Cryogenic Treatment ◽

Test Matrix ◽

Wear Rates ◽

Low Wear ◽

Wear Tests

The aim of this work is to evaluate the effect of a deep cryogenic treatment (DCT) on the wear behavior and on the microstructure of an aluminum alloy. In order to compare the level of improvement on the wear resistance provided by the DCT with a more traditional technique, a test matrix which included DCT, CrN coated specimens, and combinations of both modification methods was conducted. The wear behavior was investigated using microabrasive wear tests. The cryogenic treated specimens proved to have similar low wear rates as the specimens coated with CrN. The most distinct improvement was reached with a combination of both techniques. In the case of the DCT, the performed microstructural analysis identified the generation of additional GP-zones as the reason for the improved wear resistance.

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The Sclerometrical, Mechanical, and Wear Behavior of Mg-Y-Nd Magnesium Alloy after Deep Cryogenic Treatment Combined with Heat Treatment

Materials ◽

10.3390/ma14051218 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1218

Author(s):

Adrian Barylski ◽

Krzysztof Aniołek ◽

Grzegorz Dercz ◽

Marian Kupka ◽

Izabela Matuła ◽

...

Keyword(s):

Heat Treatment ◽

Abrasive Wear ◽

Precipitation Hardening ◽

Wear Behavior ◽

Cryogenic Treatment ◽

Solution Treatment ◽

Precipitation Process ◽

Deep Cryogenic Treatment ◽

Β Phase ◽

Fold Reduction

The paper investigates changes in the structure, microhardness, and sclerometrical and tribological properties of a Mg-Y-Nd alloy under the influence of deep cryogenic treatment (DCT) in combination with heat treatment. The solution treatment was carried out at 545 °C for 8 h, aging was carried out at 250 °C for 24 h, and the deep cryogenic treatment applied at different treatment stages was performed at −196 °C. Tests showed a significant increase in the number of β-phase precipitates identified as Mg46.1Y6.25RE3.45 in the alloy subjected to DCT after solution treatment followed by aging. In addition, an approximately 20% reduction of the grain size was observed. Changes in the structure in the precipitation process strengthened the alloy and resulted in an increase of its hardness. At the same time, sclerometric tests allowed the micromechanism of wear and the coefficient of resistance to abrasive wear to be determined. Tribological tests showed a three-fold reduction in the volumetric wear and a considerable reduction of the friction coefficient, with the main mechanism observed during friction being abrasive wear. The most favorable properties of the alloy were obtained after precipitation hardening combined with DCT, resulting in a large increase in resistance to abrasive wear. Additionally, the formation of deep scratches in the examined material was reduced. The introduction of sub-zero treatment reduces the precipitation hardening time, and the results obtained indicate that the service life of the Mg-Y-Nd alloy can be extended.

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Uptake, Internalization and Degradation of the Novel Plasminogen Activator Reteplase (BM 06.022) in the Rat

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649973 ◽

1995 ◽

Vol 74 (06) ◽

pp. 1501-1510 ◽

Cited By ~ 7

Author(s):

J Kuiper ◽

H van de Bilt ◽

U Martin ◽

Th J C van Berkel

Keyword(s):

Plasminogen Activator ◽

Liver Cells ◽

The Novel ◽

Uptake Mechanism ◽

Liver Uptake ◽

Lysosomal Compartment ◽

Β Phase ◽

Α Phase ◽

Parenchymal Liver

SummaryThe catabolism of the novel plasminogen activator reteplase (BM 06.022) was described. For this purpose BM 06.022 was radiolabelled with l25I or with the accumulating label l25I-tyramine cellobiose (l25I-TC).BM 06.022 was injected at a pharmacological dose of 380 μg/kg b.w. and it was cleared from the plasma in a biphasic manner with a half-life of about 1 min in the α-phase and t1/2of 20-28 min in the β-phase. 28% and 72% of the injected dose was cleared in the α-phase and β-phase, respectively. Initially liver, kidneys, skin, bones, lungs, spleen, and muscles contributed mainly to the plasma clearance. Only liver and the kidneys, however, were responsible for the uptake and subsequent degradation of BM 06.022 and contributed for 75% to the catabolism of BM 06.022. BM 06.022 was degraded in the lysosomal compartment of both organs. Parenchymal liver cells were responsible for 70% of the liver uptake of BM 06.022. BM 06.022 associated rapidly to isolated rat parenchymal liver cells and was subsequently degraded in the lysosomal compartment of these cells. BM 06.022 bound with low-affinity to the parenchymal liver cells (550 nM) and the binding of BM 06.022 could be displaced by t-PA (IC50 5.6 nM), indicating that the low-density lipoprotein receptor-related protein (LRP) could be involved in the binding of BM 06.022. GST-RAP, which is an inhibitor of LRP, could in vivo significantly inhibit the uptake of BM 06.022 in the liver.It is concluded that BM 06.022 is metabolized primarily in the liver and the kidneys. These organs take up and degrade BM 06.022 in the lysosomes. The uptake mechanism of BM 06.022 in the kidneys is unknown, while LRP is responsible for a low-affinity binding and uptake of BM 06.022 in parenchymal liver cells.

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