Research on Fluctuations in Work Hardening Rate of a Fe-Mn-Al-C Steel

2015 ◽  
Vol 817 ◽  
pp. 288-292 ◽  
Author(s):  
Chao Zhao ◽  
Ren Bo Song ◽  
Lei Feng Zhang ◽  
Fu Qiang Yang ◽  
Shuai Qin
Keyword(s):  
Electron Microscopy ◽  
Work Hardening ◽  
True Strain ◽  
Rate Curve ◽  
Heat Treated Sample ◽  
Transmission Electron ◽  
Heat Treated ◽  
Treated Sample ◽  
Fluctuation Range ◽  
Work Hardening Rate

The fluctuations in the work hardening rate of a Fe-12Mn-10Al-0.7C (wt. %) steel have been investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The work hardening rate of the heat treated sample had a tendency of decrease with fluctuations. The first raise in the work hardening rate curve at about 2% true strain is attributed to the shearing of the small ferrite grains by austenite, and the deformation induced twinning can contribute to the raise and drop in the work hardening rate curve. The second fluctuation range at the true strain between 10% and 14% is mainly related to the activation of planar slip on the principle slip plane which is suppressed by twins in austenite.

The Effect of Deformation on the Work Hardening Behaviour after Aging of Two Commercial Al-Mg-Si Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 261-266 ◽  
Author(s):  
Michal Kolar ◽  
Ketill Olav Pedersen ◽  
Sverre Gulbrandsen-Dahl ◽  
Thiemo Brüggemann ◽  
Knut Marthinsen
Keyword(s):  
Aging Time ◽  
Work Hardening ◽  
Natural Aging ◽  
Tensile Tests ◽  
Engineering Strain ◽  
Transmission Electron ◽  
Aging Response ◽  
Heat Treated ◽  
Work Hardening Rate ◽  
Commercial Aluminium

In order to investigate the effect of deformation on the aging response of Al-Mg-Si alloys, a series of tensile tests have been designed and carried out on two commercial aluminium alloys, i.e. AA6060 and AA6082. Extruded and solution heat treated specimens were pre-deformed 0%, 5%, and 10% (engineering strain), respectively followed by natural aging (NA). It was observed that the work-hardening rate increases with prolonged natural aging time and decreases with increasing pre-deformation prior to natural aging. The most significant effect of deformation was obtained for T4 temper i.e. after 1000 and 10000 minutes NA for the 6082 and 6060 alloy, respectively, when the amount of pre-deformation is 10%. A remarkable difference in work-hardening rate at the level of small plastic strains was observed compared to that of the material naturally aged for only 10 minutes. In addition to the tensile tests, transmission electron microscopy (TEM) has been used to characterize dislocation evolution for various combinations of pre-deformation and aging time.

The effect of small additions of Cu on precipitation in Al-Mg-Si alloys

1990 ◽  
Vol 48 (2) ◽  
pp. 442-443
Author(s):  
M. Tamizifar ◽  
G. Cliff ◽  
R.W. Devenish ◽  
G.W. Lorimer
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
Argon Atmosphere ◽  
Age Hardening ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Analytical Electron ◽  
Scanning Transmission

Small additions of copper, <1 wt%, have a pronounced effect on the ageing response of Al-Mg-Si alloys. The object of the present investigation was to study the effect of additions of copper up to 0.5 wt% on the ageing response of a series of Al-Mg-Si alloys and to use high resolution analytical electron microscopy to determine the composition of the age hardening precipitates.The composition of the alloys investigated is given in Table 1. The alloys were heat treated in an argon atmosphere for 30m, water quenched and immediately aged either at 180°C for 15 h or given a duplex treatment of 180°C for 15 h followed by 350°C for 2 h2. The double-ageing treatment was similar to that carried out by Dumolt et al. Analyses of the precipitation were carried out with a HB 501 Scanning Transmission Electron Microscope. X-ray peak integrals were converted into weight fractions using the ratio technique of Cliff and Lorimer.

Enhanced Hydrolytic Stability of Porous Boron Nitride via the Control of Crystallinity, Porosity and Chemical Composition

2018 ◽  
Author(s):  
Ravi Shankar ◽  
Sofia Marchesini ◽  
Camille Petit
Keyword(s):  
Boron Nitride ◽  
Hydrolytic Stability ◽  
Chemical Properties ◽  
Spectroscopic Techniques ◽  
High Porosity ◽  
Heat Treated Sample ◽  
Heat Treated ◽  
Treated Sample ◽  
Molecular Separations ◽  
High Degree

Porous boron nitride is gaining significant attention for applications in molecular separations, photocatalysis, and drug delivery. All these areas call for a high degree of stability (or a controlled stability) over a range of chemical environments, and particularly under humid conditions. The hydrolytic stability of the various forms of boron nitride, including porous boron nitride, has been sparingly addressed in the literature. Here, we map the physical-chemical properties of the material to its hydrolytic stability for a range of conditions. Using analytical, imaging and spectroscopic techniques, we identify the links between the hydrolytic instability of porous boron nitride and its limited crystallinity, high porosity as well as the presence of oxygen atoms. To address this instability issue, we demonstrate that subjecting the material to a thermal treatment leads to the formation of crystalline domains of h-BN exhibiting a hydrophobic character. The heat-treated sample exhibits enhanced hydrolytic stability, while maintaining a high porosity. This work provides an effective and simple approach to producing stable porous boron nitride structures, and will progress the implementation of the material in applications involving interfacial phenomena.<br>

Copper(I) Halide Nanoparticle-dispersed Glasses Prepared by Copper Staining

2005 ◽  
Vol 20 (9) ◽  
pp. 2480-2485 ◽  
Author(s):  
Kohei Kadono ◽  
Tatsuya Suetsugu ◽  
Takeshi Ohtani ◽  
Toshihiko Einishi ◽  
Takashi Tarumi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Surface Region ◽  
Borosilicate Glasses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Depth Profiles ◽  
Transmission Electron ◽  
Heat Treated ◽  
Glass Heat

Copper(I) chloride and bromide nanoparticle-dispersed glasses were prepared by means of a conventional copper staining. The staining was performed by the following process: copper stain was applied on the surfaces of Cl−- or Br−-ion-containing borosilicate glasses, and the glasses were heat-treated at 510 °C for various times. Typical exciton bands observed in the absorption spectra of the glasses after the heat treatment indicated that CuCl and CuBr particles were formed in the surface region of the glasses. The average sizes of the CuCl and CuBr particles in the glasses heat-treated for 48 h were estimated at 4.8 and 2.7 nm, respectively. The nanoparticles were also characterized by x-ray diffraction and transmission electron microscopy. Depth profiles of Cu and CuBr concentration in the glass heat-treated for 48 h were measured. Copper decreased in concentration monotonously with depth, reaching up to 60 μm, while the CuBr concentration had a maximum at about 25 μm in depth.

Microstructure Evolution of Hydrogenated Ti6Al4V Alloy during Compression

2012 ◽  
Vol 190-191 ◽  
pp. 517-521
Author(s):  
Bao Guo Yuan ◽  
Qiang Chen ◽  
Hai Ping Yu ◽  
Ping Li ◽  
Ke Min Xue ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Density ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
True Strain ◽  
True Stress ◽  
Compression Tests ◽  
Transmission Electron ◽  
Good Repeatability

Compression tests of the hydrogenated Ti6Al4V0.2H alloy were carried out using an Instron 5569 machine at room temperature. True stress-strain curves of the hydrogenated Ti6Al4V0.2H alloy under different compressive strains were obtained. Microstructure evolution of the hydrogenated Ti6Al4V0.2H alloy during the process of compression was investigated by optical microscopy and transmission electron microscopy. Results show that true stress-true strain curves of Ti6Al4V0.2H alloy have good repeatability. The deformation of grains, the dislocation density and slipping evolution during the process of compression are discussed.

Microstructure and Properties of Heat-Treated 440C Martensitic Stainless Steel

2013 ◽  
Vol 334-335 ◽  
pp. 105-110 ◽  
Author(s):  
Siti Hawa Mohamed Salleh ◽  
Mohd Nazree Derman ◽  
Mohd Zaidi Omar ◽  
Junaidi Syarif ◽  
S. Abdullah
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Stainless Steel ◽  
Martensitic Stainless Steel ◽  
Ferrite Matrix ◽  
Rapid Quenching ◽  
Heat Treated Sample ◽  
Treatment Processes ◽  
Heat Treated ◽  
Treated Sample

440C martensitic stainless steels are widely used because of their good mechanical properties. The mechanical properties of 440C martensitic stainless steel were evaluated after heat treatment of these materials at various types of heat treatment processes. The initial part of this investigation focused on the microstructures of these 440C steels. Microstructure evaluations from the as-received to the as-tempered condition were described. In the as-received condition, the formations of ferrite matrix and carbide particles were observed in this steel. In contrast, the precipitation of M7C3carbides and martensitic structures were present in this steel due to the rapid quenching process from the high temperature condition. After precipitation heat treatment, the Cr-rich M23C6carbides were identified within the structures. Moreover, a 30 minutes heat-treated sample shows the highest value of hardness compared to the others holding time. Finally, the tempering process had been carried out to complete the whole heat treatment process in addition to construct the secondary hardening phenomenon. It is believed that this phenomenon influenced the value of hardness of the 440C steel.

Thermal Conductivity of Heat Treated and Non-Heat Treated Individual Multiwalled Carbon Nanotubes

2011 ◽  
Author(s):  
Michael F. P. Bifano ◽  
Pankaj B. Kaul ◽  
Vikas Prakash
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Multiwalled Carbon ◽  
Heat Treated Sample ◽  
Heat Treated ◽  
Treated Sample ◽  
Annealing Heat Treatment

Thermal conductivity measurements of commercially available CVD grown individual multiwalled carbon nanotubes (MWCNTs) are reported. The measurements are performed using the three-omega-based Wollaston T-Type probe method inside a scanning electron microscope (SEM). An average 385% increase in thermal conductivity is measured for those MWCNTs samples which undergo a 20 hour 3000°C post annealing heat treatment. However, in most samples qualitatively characterized defects are found to negate any advantage of the heat treatment process. The highest thermal conductivity measured is 893.0 W/mK and is of a heat-treated sample. These results will help to improve the quality of MWCNT production and aid in the development of highly efficient CNT-structured thermal management devices and engineering materials.

scholarly journals White-Ceramic Conversion on Ti-29Nb-13Ta-4.6Zr Surface for Dental Applications

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Akiko Obata ◽  
Eri Miura-Fujiwara ◽  
Akimitsu Shimizu ◽  
Hirotaka Maeda ◽  
Masaaki Nakai ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Pure Titanium ◽  
Average Roughness ◽  
Heat Treated Sample ◽  
Cell Compatibility ◽  
Heat Treated ◽  
Treated Sample ◽  
Mouse Osteoblast ◽  
Cp Ti

Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy has excellent mechanical properties and bone conductivity. For dental application, TNTZ surfaces were converted to white oxidized layer by a simple heat treatment in air to achieve the formation of aesthetic surfaces. The oxidized layer formed by the heat treatment at 1000°C for 0.5 or 1 hr was whiter and joined to TNTZ substrate more strongly than that formed by the treatment at 900°C. The layer consisted of TiO2(rutile), TiNb2O7, and TiTa2O7and possessed ~30 μm in thickness for the sample heat-treated at 1000°C and ~10 μm for that heat-treated at 900°C. The surface average roughness and the wettability increased after the heat treatment. The spreading and proliferation level of mouse osteoblast-like cell (MC3T3-E1 cell) on the heat-treated sample were almost the same as those on as-prepared one. The cell spreading on TNTZ was better than those on pure titanium (CP Ti) regardless of the heat treatment for the samples. There was no deterioration in thein vitrocell compatibility of TNTZ after the oxidized layer coating by the heat treatment.

Morphological changes of poly(tetrafluoroethylene) by heat treatment on NaCl

1993 ◽  
Vol 8 (11) ◽  
pp. 2942-2947 ◽  
Author(s):  
Sadaatsu Yamaguchi ◽  
Masaki Tsuji
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
Morphological Changes ◽  
Dark Field ◽  
Exothermic Peak ◽  
Lateral Side ◽  
Cooling Process ◽  
Transmission Electron ◽  
Heat Treated

Fine granules of poly(tetrafluoroethylene) (PTFE) were heat-treated/annealed on NaCl near its melting temperature (Tm) and/or at a temperature (Tc) between upper and lower feet of the exothermic peak in the DSC cooling process from Tm. Morphological changes of the granules were examined in the bright- and dark-field modes by transmission electron microscopy. When the granules were heat-treated near Tm, microfibrils of 20–30 nm in width and fibrils of 70–120 nm in width came out of the granules. The microfibrils were also observed in the fibrils. The microfibrils formed by heat treatment near Tm seemed to be identified as microfibrils of 20–30 nm in width which were recognized outside the granules annealed at Tc. It is expected that such a microfibril will grow to be a band in the band structure observed on the surface of bulk PTFE. Since the 0015 dark-field images showed that the PTFE chains in such microfibrils and fibrils are set perpendicular to their fibril axis, the chains should fold back and forth repeatedly at both lateral side-surfaces of the microfibrils and fibrils.

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