Increase In Degree Of Deformation Research Articles

Effects of thermal ε martensite content and deformation on damping capacity of a Co–32 wt.% Ni alloy

Abstract The damping capacity of Co–32 wt.% Ni alloy was investigated as a function of the amount of thermal and strain-induced e martensite under non-magnetic and 900 Oe magnetic fields, respectively. The damping capacity of the Co–32 wt.% Ni alloy containing e martensite without magnetic field consists of the magneto-mechanical damping capacity of mainly α phase, damping capacities of α and e phases without magneto-mechanical damping effect. Under a magnetic field of 900 Oe, the more the thermal e martensite mass fraction the higher the damping capacity. However, the damping capacity of the deformed Co–32 wt.% Ni alloy with the strain-induced e martensite decreases with increasing deformation degree despite the increase in total e martensite fraction, because the lattice defects like dislocations introduced during deformation act as barriers to movement of damping sources such as magnetic domain walls, stacking faults boundaries in both α and e phases, and α/e interfaces.

Effect of plastic deformation on the transport phenomena in Pb0.95Sn0.05Se single crystals

Abstract The temperature dependences of the Hall coefficient and specific resistance were investigated in the range 77–350 K for plastically deformed Pb0.95Sn0.05Se single crystals. The undeformed samples had a hole conductivity. It was found that the dislocations being introduced under a single-slip mode had a donor effect. As the deformation degree increases, the acceptor action is compensated, which leads to the inversion of conductivity type in a narrow dislocation concentration N D interval with a subsequent rise in the electronic conductivity. The results can be explained by a mechanism of intrinsic point-defect formation during the slip process of the screw and split edge dislocations with jogs. The Hall mobility investigations show that, in the deformed crystals, scattering by both phonons and lattice statistical defects is a factor. The role of these defects increases with increase in the dislocation concentration and decrease in the temperature. The temperature dependence of mobility decays and ...

Einfluss Der Verformung Bei 77°K Auf Die Elektrochemischen Eigenschaften Der Oberfläche Von Nickeleinkristallen

Monocrystalline nickel with a (110 surface orientation was deformed during rolling in liquid nitrogen in a low-temperature rolling installation. The degree of deformation constituted 9, 23, 40 and 83 per cent. Plarization curves of deformed single crystal nickel showed that anodic oxidation processes depend on the degree of metal deformation. With the increase in degree of deformation the transition of monocrystalline nickel to the passive state is facilitated. It is evident from the deceleration of the dissolution rate in the region of the active state of the surface, from the decrease of critical passivation current as well as from the shifting of critical passivation potential towards the less noble values. Electron microscopic investigation has shown that the growth of the deformation degree results in an accumulation of faults in the crystal lattice. The growth of single crystal nickel susceptibility to passivation with the increase of deformation degree can be explained by the fact that growth of dislocation density leads to the increase of the number of nickel-oxygen compounds formation centres.

Investigation of the friction of rubber under constant compressive strain conditions at low pressure

A vacuum tribometer was developed which was used to investigate the maximum friction force occurring at the initial instant of slipping in rubber-metal friction pairs under conditions of a given (from 5 to 40%) compressive strain at a low pressure in the temperature range from +100 to −100°C. Filled rubbers on a base of nitrile-butadiene rubbers were studied. Up to the glass transition temperature Tg the vacuum had practically no effect on the maximum friction frocefm; at temperatures Tg and lower the values offm obtained in a vacuum were 10–15% higher than those obtained in the atmosphere. It is shown that with a decrease of temperature from 20°C to the glass transition temperature Tg the slope of the dependence of the maximum friction force on the degree of deformation increases, and below Tg decreases. The effect of the slipping speed v on the maximum friction forcefm was also studied.

Ultrasonic treatment of alloy MA2-1 during solidification

1. Ultrasonic treatment during solidification of high-purity MA2-1 ingots substantially increases (∼50%) the ductility of the ingots and wrought semifinished products. 2. The increase in the permissible degree of deformation of alloy MA2-1 after ultrasonic treatment will increase labor productivity.

Method for determining the changes in the energy stored by a metal during plastic deformation

1. It is very important to know the dependence of the stored energy on the degree of deformation in a study of plastic deformation and in an evaluation of the strength of metals. A calorimeter has been used on occasion to measure the stored energy [2–4], but in practice this method is limited to cases of uniform deformation. It is not applicable in the case of local deformation, and especially during destruction. 2. The method of analyzing the deformation dependence of the stored energy, used during twisting tests, is based on a thermocouple measurement of the heat evolved [8, 9]. 3. A new method has been proposed, in which the stored energy (ws) at a point on the surface of the smallest (or largest, for compression) cross section of the sample is calculated as the difference between the external work (wex) and the heat (wT) evolved during the deformation [Eq. (1)]; i.e., the plastic deformation and destruction can be studied on an energetic basis. The method has been used to study the deformation dependence of the energy stored in high-purity nickel. 4. As the degree of deformation increases, the external work increases monotonically, while the heat evolution is characterized by four discrete regions.

Thermal stability of hardening of steel Kh18N10T resulting from mechanicothermal treatment

1. High-temperature mechanicothermal treatment at 900–1100\dgC with 12–15 and 25–28% reduction notably increases the strength characteristics of steel Kh18N10T but reduces the plasticity only slightly. The strength increases as the rolling temperature decreases and the degree of deformation increases. 2. The thermal stability of the hardening resulting from HTMTT under conditions completely preventing recrystallization depends very little on the rolling temperature but mainly on the degree of reduction. The thermal stability is highest after 12–15% reduction at 900–1000°C. 3. The partial development of recrystallization during high-temperature deformation sharply reduces the thermal stability of the cold hardening resulting from HTMTT.