scholarly journals The relationship between activation–passivation transition and grain boundary dissolution on four steel samples in acidic solutions containing NO2−

RSC Advances ◽  
2019 ◽  
Vol 9 (41) ◽  
pp. 23589-23597 ◽  
Author(s):  
Yong Zhou ◽  
Pei Zhang ◽  
Jinping Xiong ◽  
Fuan Yan
Keyword(s):  
Grain Boundary ◽  
Electrochemical Tests ◽  
Acidic Solutions ◽  
Boundary Dissolution ◽  
The Relationship

The relationship between activation–passivation transition and grain boundary dissolution for L80, N80, X65 and Q235 steels in HNO3, HCl, HAc and CO2 solutions containing NO2− was studied by electrochemical tests and microstructural observations.

Effects of Microstructures on the Mechanical Properties of Dilute Al-Si Alloys

2007 ◽  
Vol 345-346 ◽  
pp. 821-824
Author(s):  
Keiyu Nakagawa ◽  
Teruto Kanadani
Keyword(s):  
Fatigue Strength ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Aging Time ◽  
Fracture Elongation ◽  
Micro Cracks ◽  
Hand Fracture ◽  
Stress Cycles ◽  
Effects Of Aging ◽  
The Relationship

In this paper, we investigated effects of aging at 473K on the relationship between microstructure in the vicinity of the grain boundaries and fatigue strength for Al-1.2%Si alloy. Results obtained show the following features. (1) As aging time, tA increase, the tensile strength (σB) and 0.2% proof stress (σ0.2) increase slowly, but gradually decrease after reaching a maximum at around 18 ks. On the other hand, fracture elongation shows an opposite trend, suggesting that at aging times above 18ks, over aging occurs. (2) The fatigue strength lowers with increasing aging time, however, when the aging time is more than 18 ks at 473K, the fatigue strength remains almost the same. (3) When the aging time is more than 6 ks, grain boundary precipitates with a size greater than several 10s of nm are observed. (4) When the aging time is 18 ks, an accumulation of dislocations are observed at the grain boundaries and in the vicinity of grain boundary precipitates, and dislocations increase with the number of stress cycles. (5) When the aging time is more than 6 ks, the fatigue fracture surface is mainly intergranular. These results suggest that reduction of fatigue strength results from propagation of micro-cracks which are initiated at the large precipitates on the grain boundaries.

Relationship Between Acid Intergranular Corrosion and Caustic Stress Corrosion Cracking of Alloy 600

CORROSION ◽  
1977 ◽  
Vol 33 (1) ◽  
pp. 20-26 ◽  
Author(s):  
G. J. THEUS
Keyword(s):  
Heat Treatment ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Alloy 600 ◽  
Intergranular Attack ◽  
Electrochemical Tests ◽  
Stress Relieving ◽  
Service Conditions ◽  
The Relationship

Abstract Modified Streicher and 288 C (550 F) electrochemical caustic stress corrosion tests were performed on Alloy 600 to determine the relationship between acid intergranular attack susceptibility and caustic stress corrosion cracking (SCC) susceptibility. Mill annealed and solution annealed materials with and without a subsequent 621 C (1150 F) heat treatment (simulated stress relief) were evaluated. Susceptibility to attack in the Streicher test was greatest for material that had received a 621 C (1150 F) heat treatment, whereas this heat treatment caused the same material to be least susceptible to cracking in the electrochemical tests. The conclusions drawn from these results are: (1) stress relieving Alloy 600 does improve its resistance to caustic SCC, and (2) resistance of Alloy 600 to acid intergranular attack does not imply resistance of Alloy 600 to caustic SCC. Therefore, the results demonstrate the need for selecting corrosion qualification tests which are relevant to service conditions.

The relationship between carrier mobility and bicrystalline grains boundary of rutile TiO2 film

2019 ◽  
Vol 33 (16) ◽  
pp. 1950176
Author(s):  
Yanfei He ◽  
Xin Zhang ◽  
Yuanbing Liu ◽  
Hao Liu ◽  
Yi Zhang ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Grain Boundary ◽  
Carrier Mobility ◽  
Large Angle ◽  
Air Atmosphere ◽  
Sensor Field ◽  
Sputtering Power ◽  
Measurement Results ◽  
Rutile Titanium Dioxide ◽  
The Relationship

The rutile titanium dioxide (TiO2) has attracted enormous interest in sensor field owing to its stability at high temperature. But less is known about electron transfer efficiency of rutile TiO2, which is mainly influenced by the electron mobility. The aim of this study is to investigate the relationship between carrier mobility and bicrystalline grains boundary of rutile TiO2 film. In this study, TiO2 film was deposited by the direct current pulsed magnetron sputtering technology with sputtering power from 150 to 900 W. Then the TiO2 films were annealed at [Formula: see text] in air atmosphere. By this way, the rutile TiO2 films were obtained. Special attention was paid to the carrier mobility of rutile TiO2 films. The Hall measurement results showed that with the increase of sputtering power from 150 to 900 W, the carrier mobility of rutile TiO2 films increased from 0.75 to [Formula: see text], gradually. Taking the TEM and SAED results together, our data indicated that the carrier mobility of rutile TiO2 film was influenced by the bicrystalline grains boundary. The large angle bicrystalline grain boundary seriously deteriorates the carrier mobility of rutile TiO2 film. On the contrary, the low angle bicrystalline grain boundary has little influence on the carrier mobility of rutile TiO2 film.

Surface Dissolution of Hydroxyapatite Prepared by Microwave Sintering

2007 ◽  
Vol 330-332 ◽  
pp. 227-230
Author(s):  
Dong Seok Seo ◽  
Hwan Kim ◽  
Kyu Hong Hwang ◽  
Jong Kook Lee
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Heating Rate ◽  
Microwave Sintering ◽  
Starting Material ◽  
Dissolution Behavior ◽  
Distilled Water ◽  
Sintering Process ◽  
Conventional Sintering ◽  
Boundary Dissolution

The aim of this study was to prepare dense hydroxyapatite (HA) by microwave sintering and to evaluate the dissolution behavior in distilled water. Commercially-obtained HA powders having Ca/P ratio of 1.67 were used as a starting material. The as-received powder of granular type consists of nano-sized particles. Microwave sintering was operated at 1200°C for 5 min with a heating rate of 50°C/min. Microwave sintering process reduced grain size of HA, compared with the case of conventional sintering. During the immersion in distilled water for 3-14 days, grain boundary dissolution occurred and the dissolution extended into the bulk following this path. As a result, particles were separated from the structure leaving micron-scale defects.

Slow Crack Growth by Grain Boundary Dissolution of Hydroxyapatite in Water

2011 ◽  
Vol 488-489 ◽  
pp. 428-431
Author(s):  
Dong Seok Seo ◽  
Kyu Hong Hwang ◽  
Jong Kook Lee
Keyword(s):  
Surface Roughness ◽  
Grain Boundary ◽  
Crack Growth ◽  
Immersion Time ◽  
Slow Crack Growth ◽  
Mechanical Degradation ◽  
Liquid Environment ◽  
Hydroxyapatite Ceramics ◽  
Initial Stage ◽  
Boundary Dissolution

Mechanical degradation of hydroxyapatite ceramics due to the slow crack growth was observed in water. Microstructural crack on the surface of hydroxyapatite initiated by grain boundary dissolution in liquid environment resulting in particle loosening and microstructural-level degradation, followed by a drastic decrease of mechanical properties. In this study, slow crack growth by the dissolution behavior of hydroxyapatite ceramics was investigated based on microstructural observation by field emission microscopy. The crack growth and morphological change of hydroxyapatite surface, especially at the initial stage of dissolution and related surface roughness were observed with immersion time. The surface dissolution occurred from the initial stage of immersion showing increase in surface roughness. Following certain period of immersion time, the surface dissolution initiated at grain boundaries and generated many separated grains.

A Comparison of Grain Boundary Monolayer Segregation Measurements Made Using Fegstem and Auger Spectroscopy

1996 ◽  
Vol 439 ◽  
Author(s):  
S. B. Fisher ◽  
P. Spellward ◽  
R. Scowen ◽  
B. Lee
Keyword(s):  
Grain Boundary ◽  
Boundary Data ◽  
Auger Spectroscopy ◽  
Theoretical Description ◽  
Electron Optics ◽  
Highly Active ◽  
Active Electron ◽  
Nickel Base ◽  
Boundary Chemistry ◽  
The Relationship

AbstractThe active electron optics suite at Magnox Electric's Berkeley Centre has a VG HB501 FEGSTEM and a FE-sourced Auger Microprobe (a Fisons Microlab-F) which are routinely used for grain boundary chemistry studies in a variety of highly active austenitic and ferritic steels and nickel base alloys.In a number of investigations sufficient grain boundary data have been obtained to allow a meaningful comparison between the two instruments to be made. It has been established that for the overwhelming majority of materials and conditions there exists a reasonable correlation between the two sets of compositional (on-boundary) data.This paper presents this correlation and gives a simple theoretical description justifying the relationship between the raw data from the instruments. Examples are given of materials and conditions for which the correlation cannot be established and this leads to a discussion of the usefulness of the availability of the correlation.

Study of Bonding of Grain Boundaries in Steels Using EELS

2005 ◽  
Vol 475-479 ◽  
pp. 4063-4066
Author(s):  
X. Zhang ◽  
Lina Zhang ◽  
Jun Jie Qi ◽  
Yue Ma
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Intergranular Fracture ◽  
Fracture Mode ◽  
Fracture Property ◽  
Transgranular Fracture ◽  
The Difference ◽  
Relationship Of ◽  
The Relationship

A novel EELS technique was developed to study bonding of grain boundary in many kinds of steels. We measured the normalized intensities of Fe white lines and calculated the occupancies of 3d states of iron, and then analyzed the relationship of the occupancies of 3d states of iron and the fracture property of the steels. We found that if the grain boundary has a different occupancy of 3d state of iron from that of the bulk, the steel tends to have an intergranular fracture, whereas if the grain boundary has almost the same occupancy of 3d state as the bulk, the steel tends to have a transgranular fracture. Our result shows that the difference in the occupancy of 3d state between bulk and grain boundary can be used to study the fracture mode at grain boundary in steel.

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