Influence of Repeated Thermo-Mechanical Treatment on the Temperature Dependence of the Internal Friction of Iron

1967 ◽  
pp. 140-145
Author(s):  
L. K. Gordienko
Keyword(s):  
Internal Friction ◽  
Temperature Dependence ◽  
Mechanical Treatment ◽  
Thermo Mechanical Treatment

Metallurgical Effects of Grain Boundary Ledges

1977 ◽  
Vol 35 ◽  
pp. 126-129
Author(s):  
L.E. Murr
Keyword(s):  
Grain Boundary ◽  
Quantitative Data ◽  
Mechanical Treatment ◽  
Unit Length ◽  
Physical And Mechanical Properties ◽  
Direct Observations ◽  
Transmission Electron ◽  
Properties Of Materials ◽  
Thermo Mechanical Treatment ◽  
Ledge Density

Ledges in grain boundaries can be identified by their characteristic contrast features (straight, black-white lines) distinct from those of lattice dislocations, for example1,2 [see Fig. 1(a) and (b)]. Simple contrast rules as pointed out by Murr and Venkatesh2, can be established so that ledges may be recognized with come confidence, and the number of ledges per unit length of grain boundary (referred to as the ledge density, m) measured by direct observations in the transmission electron microscope. Such measurements can then give rise to quantitative data which can be used to provide evidence for the influence of ledges on the physical and mechanical properties of materials.It has been shown that ledge density can be systematically altered in some metals by thermo-mechanical treatment3,4.

Fracture Toughness of Large Forgings for Power Producing Industry

2013 ◽  
Vol 577-578 ◽  
pp. 593-596 ◽  
Author(s):  
Václav Mentl
Keyword(s):  
Fracture Toughness ◽  
Chemical Composition ◽  
Steam Turbine ◽  
Mechanical Treatment ◽  
Material Degradation ◽  
The Real ◽  
Operational Safety ◽  
Local Properties ◽  
Thermo Mechanical Treatment ◽  
Shape And Size

The steam turbine rotors represent large components both in radial and axial directions. Their local properties generally differ from one forging to another, or if we compare head and bottom parts of the original ingot, or central and circumferential localities of one rotor body respectively, or if we compare the properties of separate discs e.g. in the case of welded rotors. These differences stem from both even slight changes in the chemical composition (of separate heats or even within one ingot) and thermo-mechanical treatment and in the differences in technology with respect to the real shape and size of the forgings in question. In the paper, the consequences of the differences in fracture toughness characteristics in various rotor localities are discussed with respect to the rotors operational safety taking into account the existence of cracks and material degradation.

scholarly journals A thermo-mechanical machining method for improving the accuracy and stability of the geometric shape of long low-rigidity shafts

2021 ◽  
Author(s):  
Antoni Świć ◽  
Arkadiusz Gola ◽  
Łukasz Sobaszek ◽  
Natalia Šmidová
Keyword(s):  
Heat Treatment ◽  
Cross Section ◽  
Mechanical Treatment ◽  
Geometric Shape ◽  
Different Dimensions ◽  
Thermo Mechanical Treatment ◽  
Mechanical Machining ◽  
Simultaneous Heat ◽  
Accuracy And Stability

AbstractThe article presents a new thermo-mechanical machining method for the manufacture of long low-rigidity shafts which combines straightening and heat treatment operations. A fixture for thermo-mechanical treatment of long low-rigidity shafts was designed and used in tests which involved axial straightening of shafts combined with a quenching operation (performed to increase the corrosion resistance of the steel used as stock material). The study showed that an analysis of the initial deflections of semi-finished shafts of different dimensions and determination of the maximum corrective deflection in the device could be used as a basis for performing axial straightening of shaft workpieces with simultaneous heat treatment and correction of the initial deflection of the workpiece. The deflection is corrected by stretching the fibers of the stock material, at any cross-section of the shaft, up to the yield point and generating residual stresses symmetrical to the axis of the workpiece. These processes allow to increase the accuracy and stability of the geometric shape of the shaft.

Mechanical Spectroscopy Study on the Light Soaking Effect on Hydrogenated Amorphous Silicon

2012 ◽  
Vol 184 ◽  
pp. 416-421 ◽  
Author(s):  
H. Mizubayashi ◽  
I. Sakata ◽  
H. Tanimoto
Keyword(s):  
Internal Friction ◽  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Wide Distribution ◽  
Activation Energies ◽  
Mechanical Spectroscopy ◽  
Induced Changes ◽  
Mild Temperature ◽  
Hydrogenated Amorphous

For hydrogenated amorphous silicon (a-Si:H) films deposited at temperatures between 423 K and 623 K (a-Si:H423Kand so on), the light-induced changes in the internal friction between 80 K and 400 K were studied. The internal friction is associated with H2motion in microvoid networks, and shows the mild temperature dependence between about 80 K and 300 K (Q-180-300K) and the almost linear increase above 300 K (Q-1>300K). BothQ-180-300KandQ-1>300Kdecrease with increasing the deposition temperature, and show the mild temperature dependence ina-Si:H623K. The white light soaking with 100 mW/cm2(WLS100and so on) below 300 K caused a change inQ-180-300Kand no changes inQ-1>300K, respectively, and the light-induced changes inQ-180-300Krecovered after annealing at 423 K. The wide distribution of activation energies for H2motions between microvoids indicate that most of neighboring microvoids are connected through windows, i.e., the microvoid networks are existing ina-Si:H, and the spatially loose or solid structures are responsible for the low or high activation energies for the H2motion between microvoids, respectively. Furthermore, the light-induced hydrogen evolution (LIHE) was observed for WLS200to WLS400in a vacuum between 400 and 500 K, resulting in the disappearance of the internal friction due to the H2motion in the microvoid network.

scholarly journals Modification of Non-Metallic Inclusions by Rare-Earth Elements in Microalloyed Steels

2012 ◽  
Vol 12 (2) ◽  
pp. 129-134 ◽  
Author(s):  
M. Opiela ◽  
A. Grajcar
Keyword(s):  
Rare Earth ◽  
Chemical Composition ◽  
Rare Earth Elements ◽  
Mechanical Treatment ◽  
Induction Furnace ◽  
Microalloyed Steels ◽  
Metallurgical Process ◽  
Metallic Inclusions ◽  
Mean Size ◽  
Thermo Mechanical Treatment

Modification of Non-Metallic Inclusions by Rare-Earth Elements in Microalloyed Steels The modification of the chemical composition of non-metallic inclusions by rare-earth elements in the new-developed microalloyed steels was discussed in the paper. The investigated steels are assigned to production of forged elements by thermo-mechanical treatment. The steels were melted in a vaccum induction furnace and modification of non-metallic inclusions was carried out by the michmetal in the amount of 2.0 g per 1 kg of steel. It was found that using material charge of high purity and a realization of metallurgical process in vacuous conditions result in a low concentration of sulfur (0.004%), phosphorus (from 0.006 to 0.008%) and oxygen (6 ppm). The high metallurgical purity is confirmed by a small fraction of non-metallic inclusions averaging 0.075%. A large majority of non-metallic inclusions are fine, globular oxide-sulfide or sulfide particles with a mean size 17 μm2. The chemical composition and morphology of non-metallic inclusions was modified by Ce, La and Nd, what results a small deformability of non-metallic inclusions during hot-working.

scholarly journals Influence of combined hygro-thermo-mechanical treatment on technical characteristics of poplar wood

2018 ◽  
pp. 0-0 ◽  
Author(s):  
Reza Hajihassani ◽  
Behbood Mohebby ◽  
Saeed Kazemi Najafi ◽  
Parviz Navi
Keyword(s):  
Mechanical Treatment ◽  
Poplar Wood ◽  
Thermo Mechanical Treatment

scholarly journals EFFECT OF THERMO-MECHANICAL TREATMENT ON PROPERTIES OF PARICA PLYWOODS (Schizolobium amazonicum Huber ex Ducke)

2017 ◽  
Vol 41 (1) ◽  
Author(s):  
Mírian de Almeida Costa ◽  
Cláudio Henrique Soares Del Menezzi
Keyword(s):  
Mechanical Properties ◽  
Mechanical Treatment ◽  
Physical And Mechanical Properties ◽  
The Other ◽  
Modulus Of Rupture ◽  
Thermal Treatments ◽  
Mechanical Compression ◽  
Specific Mass ◽  
Thermo Mechanical Treatment ◽  
Temperature And Pressure

ABSTRACT Thermo-mechanical treatment is a technique for wood modification in which samples are densified by means of heat and mechanical compression, applied perpendicularly to fibers, which under different combinations of time, temperature, and pressure increases wood density and thus improve some of its properties. This study aimed to treat thermo-mechanically parica plywood and observe the effects on its physical and mechanical properties. Specimens were submitted to two treatments, 120 and 150 ºC, remaining under pressure for seven minutes and, subsequently, under zero pressure for 15 minutes. Results showed a significant increase in specific mass from 0.48 g cm-3 to an average of 0.56 g cm-3, and a compression ratio of about 31.7% on average. Physical properties also varied significantly and results showed that treated samples swelled and absorbed more water than those untreated, leading to a greater thickness non-return rate. This indicates the proposed thermal treatments did not release the internal compressive stress generated during panel pressing, not improving its dimensional stability as a result. On the other hand, mechanical properties were positively affected, leading to an increase of 27.5% and 51.8% in modulus of rupture after treatments at 120 and 150 ºC, respectively. Modulus of elasticity and glue-line shear strength did not vary statistically and Janka hardness was 29.7% higher after treatment at 150 ºC.

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