Effect Of Aging Temperature Research Articles

Effect of aging temperature on the structure, microhardness, and sputtering of the Kh12N23 precipitation hardening steel bombarded with argon ions

Effect of aging temperature on the structure, microhardness, and sputtering of the Kh12N23 precipitation hardening steel bombarded with argon ions

Age hardening of orthodontic beta titanium alloys

AbstractMetastable beta titanium alloys have been shown to be effective in orthodontic therapy because of their low modulus of elasticity and good springback, forming, and welding characteristics. Although used in the as‐drawn condition, these alloys are also age hardenable through precipitation of the alpha phase in the beta matrix. The effect of aging temperature, aging time, and prior cold work on the mechanical properties of fine wires of Ti‐13V‐11Cr‐3Al and Ti‐11.5Mo‐6Zr‐4.5Sn were determined. The latter alloy was more responsive to aging. Aging at 900°F for 14 h produced increases of approximately 40% in the modulus of elasticity, the yield and ultimate strengths. There was a corresponding decrease in ductility. The resulting wires could be useful in clinical situations requiring a high‐yield strength and a stiffness intermediate between as‐drawn beta titanium and stainless steel, the elastic moduli of which are 10 and 28 × 106 psi, respectively.

The Voltage Breakdown Characteristics of Miniature XLPE Cables Containing Water Trees

This paper presents the results of 60 Hz, dc, and impulse voltage breakdown tests on miniature XLPE cables containing water trees. To produce the water trees, the cables were immersed in water and subjected to high voltage at a frequency of 1 kHz for periods up to 1000 h. The dc and impulse breakdown voltages of virgin cable were similar and about twice the peak value of the ac breakdown voltage. The breakdown voltages decreased by up to 90% of their original values with time of ageing and also with ageing voltage. For well-developed water trees in the insulation, the ac and dc breakdown strengths were similar. The number and lengths of the water trees also increased with time of ageing and voltage. The breakdown voltages were almost independent of the tree density but decreased significantly with increasing tree length. The effects of ageing temperature and drying out of the cable prior to breakdown testing are also reported.

Effects of Aging Temperature on the Formation of Secondary Defects in Quenched α-Brass

Alpha-brass containing 30 wt.% Zn was quenched from a temperature near the melting point into an oil bath at various temperature ranging from 20° to 260°C and was aged in the bath. The type of secondary defects in the aged specimens was examined by transmission electron microscopy. It is found that the density of dislocation loops decreases while that of tetrahedra increases with increasing aging temperature. The result is explained in terms of the difference in the growth ability between dislocation loops and tetrahedra at the early stage of clustering of quenched-in vacancies.

Precipitation magnetic hardening in NiFe<inf>2</inf>O<inf>4</inf>-Mn<inf>3</inf>O<inf>4</inf>system

A marked magnetic hardening is observed at room temperature on compositions 35NiFe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> .65Mn <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> and 30NiFe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> .70Mn <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> in the binary system NiFe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> -Mn <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> . From the effects of aging temperature and time upon the magnetic hardening, the measurements of the change of Curie temperature by aging, the results of X-ray and chemical analyses, and microscopic and electron microscopic observations of microstructure, the new findings have been concluded to come from the precipitation of γ-Mn <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> .

Phenomenology of precipitation in copper-20 pct nickel-20 pct manganese

The precipitation phenomena in the alloy copper-20 pct nickel-20 pct manganese have been investigated. Utilizing transmission electron microscopy as the principal tool; the effects of aging temperature and time as well as prior cold work were studied. For all aging temperatures the reaction products are the solute depleted fcc solid solution and an ordered structure with fct symmetry. Three aging temperatures characterized by different precipitate morphologies were studied. At 350°C discontinuous precipitation is the predominant mode of decomposition. Precipitate colonies nucleate at grain and twin boundaries and eventually grow through the entire structure. Microtwinning of the colony matrix accompanies the precipitation reaction. At 450°C both grain boundary nucleated discontinuous precipitates and fine periodic homogeneous arrays are observed in the absence of cold work. The fine periodic arrays coarsen and eventually form nuclei for the ordered fct phase. The coarsening of the periodic arrays prohibits the growth of the discontinuous precipitate early in the process, so only a small volume fraction of discontinuous precipitate is formed at the grain boundaries. Aging subsequent to cold work results in ordered, fct precipitates heterogeneously nucleated on dislocations. At 500°C no precipitate is observed in the absence of cold work. When aging is preceded by cold work, the ordered fct phase appears as heterogeneously nucleated Widmanstatten laths. No grain boundary nucleated colonies are observed at this temperature.

1087. Dislocation structures in dehydrogenated niobium: M Amano and Y Sasaki,Phys Stat Sol (a), 19 (2), 1973, 405–414

The aging response of various Al–Zn–Mg–Cu alloys was compared with the reinforced counterpart. The effects of aging temperature and time on the mechanical properties of these alloys, was also determined. Moreover, the effects of quenching rate from solution temperature, time between quench and aging, and heating rate to precipitation temperature were investigated. The study was executed by selecting two different heat treatments for each of three different aging temperatures: one without prior straining, and the other with 2% straining prior to aging to relieve stress. Room temperature tensile testing was conducted to determine these variations of aging on the strength of the spray formed Al–Zn–Mg–Cu alloys. The presence of SiC particles accelerated the aging kinetics of the alloys compared to the unreinforced counterparts. This difference in time to peak aging decreased with decreasing aging temperature. At uniform temperatures, differences for time to peak aging between unreinforced and composite alloys also existed in both the prestrained and unstrained condition. The difference was not as great in the prestrained state. The tensile strengths increased slightly with prestraining, but not significantly. Alloys containing silver maintained high strengths over silver-free counterparts when rapidly heated to precipitation temperatures above 120 °C. At slow heating rates, however, the silver-free alloys matched or were slightly higher than the strength of silver alloys, with increasing heating rate.

1085. Measurements of dislocation pinning and dislocation damping in cold-worked copper at 1 Hz: G Sokolowski et al,Phys Stat Sol (a), 19 (2), 1973, 493–504

The aging response of various Al–Zn–Mg–Cu alloys was compared with the reinforced counterpart. The effects of aging temperature and time on the mechanical properties of these alloys, was also determined. Moreover, the effects of quenching rate from solution temperature, time between quench and aging, and heating rate to precipitation temperature were investigated. The study was executed by selecting two different heat treatments for each of three different aging temperatures: one without prior straining, and the other with 2% straining prior to aging to relieve stress. Room temperature tensile testing was conducted to determine these variations of aging on the strength of the spray formed Al–Zn–Mg–Cu alloys. The presence of SiC particles accelerated the aging kinetics of the alloys compared to the unreinforced counterparts. This difference in time to peak aging decreased with decreasing aging temperature. At uniform temperatures, differences for time to peak aging between unreinforced and composite alloys also existed in both the prestrained and unstrained condition. The difference was not as great in the prestrained state. The tensile strengths increased slightly with prestraining, but not significantly. Alloys containing silver maintained high strengths over silver-free counterparts when rapidly heated to precipitation temperatures above 120 °C. At slow heating rates, however, the silver-free alloys matched or were slightly higher than the strength of silver alloys, with increasing heating rate.

Precipitation process of Al-Mg-Si alloys by ageing

Precipitation process of Al-Mg-Si alloys during ageing was investigated by measurements of specific heat and by electron microscopy.Specific heat-temperature curves were obtained during reheating after various age-hardening treatments in four kinds of approximate pseudo-binary Al-Mg2Si system alloys; Al-0.60wt%Mg2Si-0.14wt%Mg, Al-0.99wt%Mg2Si-0.06wt%Mg, Al-1.31wt%Mg2Si-0.06wt%Mg, and Al-1.08wt%Mg2Si-0.02wt%Mg.The results were discussed in comparison with those obtained by electron microscopy. Three portions for heat evolution and other three portions for heat absorption were detected on the specific heat-temperature curves of as-quenched alloys. The former portions were represented by the formation of acicular G. P. zones, rod-form β' precipitates, and tabular β precipitates. The latter portions were represented by the re-dissolution of the G. P. zones, β' and β precipitates. The effects of ageing temperature and time on the above heat evolution and absorption were examined to investigate the precipitation process of these alloys during ageing. The difference between β' and β precipitations was distinctly observed by the specific heat-temperature curves in comparison with the results obtained by electron microscopy. Clustering of the solute atoms or formation of the G. P. zones were found to occur during the process of quenching or just after quenching before specific heat measurements.

On the influence of aging temperature and pre-strain on the stress corrosion cracking of Al-Zn-Mg alloy

Studies were made on the effects of aging temperature and pre-strain on the stress corrosion cracking of ternary Al-Zn-Mg alloys containing 4.5wt.%Zn-3wt.%Mg, 4.5wt.%Zn-2wt.%Mg, and 4.5wt.%Zn-1wt.%Mg.The results obtained were summarized as follows:(1) The alloys aged at low temperature were sensitive to the stress corrosion cracking. The fact would be due to small proof stress and high corrosion rate. The alloys aged at temperatures higher than G. P. solvus were insensitive to the stress corrosion cracking.(2) When the aging temperature was higher, the alloy having lower content of additional elements promptly turned to be more insensitive to the stress corrosion cracking as compared with that of higher content.(3) The specimen as pre-strained was more sensitive to the stress corrosion cracking than that as no prestrained. The sensitivity was greater with the increase of pre-strain.

マルエージング鋼線の機械的性質におよぼす断面減少率と時効処理条件の影響について

マルエージング鋼線の機械的性質におよぼす断面減少率と時効処理条件の影響について