Effect Of Long-term Annealing Research Articles

Effect of Long-Term Annealing on the Impact Toughness of 22K Steel

Effect of Long-Term Annealing on the Impact Toughness of 22K Steel

The Effect of Simultaneous Si and Ti/Mo Alloying on High-Temperature Strength of Fe3Al-Based Iron Aluminides.

The effect of phase composition and morphology on high-temperature strength in the compression of Fe-Al-Si-based iron aluminides manufactured by casting was investigated. The structure and high-temperature strength in the compression of three alloys—Fe28Al5Si, Fe28Al5Si2Mo, and Fe28Al5Si2Ti—were studied. Long-term (at 800 °C for 100 h) annealing was performed for the achievement of structural stability. The phase composition and grain size of alloys were primarily described by means of scanning electron microscopy equipped with energy dispersive analysis and Electron Backscatter Diffraction (EBSD). The phase composition was verified by X-ray diffraction (XRD) analysis. The effect of Mo and Ti addition as well as the effect of long-term annealing on high-temperature yield stress in compression were investigated. Both additives—Mo and Ti—affected the yield stress values positively. Long-term annealing of Fe28Al5Si-X iron aluminide alloyed with Mo and Ti deteriorates yield stress values slightly due to grain coarsening.

First- and second-order phase transitions in Fe-(17-19)at.%Ga alloys

The structure of the Fe-(17.5–19.5)at.%Ga alloys in as-cast and nearly equilibrium states is studied using XRD, ND, and EBSD. In disagreement with the existing phase diagrams, the long-term isothermally annealed at 450–500 °C Fe-17.5%Ga alloy has a two-phase structure with two co-existing ferromagnetic phases: bcc-originated A2(D03) as a matrix and a fcc-originated A1(L12) needle-shaped precipitates. The phase transitions during cooling of 17.5 and 19.5%Ga alloys from the A2 range of the phase diagram with different cooling rates were used to plot, at least partly, Time-Temperature-Transformation (TTT) diagrams. The critical cooling rates for starting first- and second-order transitions are determined for the Fe-19.5%Ga alloy. The effect of long-term annealing on magnetostriction is reported.

Thermal Stability of Ti-6Al-4V Alloy with Carbon Content

In the paper, the effect of long-term annealing (to 500 h) on the microstructure and hardness of two-phase titanium alloy which represent group of α+β (Ti-6Al-4V) with 0.7 wt. % carbon content was present. The stability of microstructure after long-term annealing was conducted to alloys in hardening state (after solution treatment and aging). Annealing was carried out at a temperature above the operating temperature of commercial titanium alloys without carbon content. The analysis of changes in the microstructure at research range of annealing time indicates its stability, which was confirmed by hardness test of investigated alloys. For comparison to Ti-6Al-4V-0.7C alloy, the microstructure stability research at 420oC was conducted for classical alloy contain no carbon. This alloy was previously subject solution and aging treatment under the same conditions as tested alloy.

The Effect of Long-Term Annealing at Elevated Temperature on Microstructure and Hardness of Heat-Resistant Steel

The stainless steel group AISI 310 is very often used for application in high-temperature conditions. This study investigated the effect of long-term annealing on microstructure and hardness of AISI 310S (24.3% Cr-19.3% Ni 1.8% Mn 0.21% Mo 0.67% Si, wt.%) heat-resistant steel. Microstructural changes and hardness distribution were analyzed after isothermal annealing at 800 °C in long-term exposure (from 1 to 1740 hours). Microstructure and fracture surface mode were analyzed using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). It was found that after annealing the sigma phase particles were precipitated at grain boundaries and within austenite grains. The chromium content in the sigma phase increased with the prolongation of annealing time. The morphology of sigma phase was changed from fine precipitates at lower annealing times to coarser particles at higher annealing times. Also, presence of sigma phase was confirmed by transmission electron microscopy (TEM). At annealing temperature of 800 °C the hardness began to increase after 16 hours. With longer times of annealing the fracture surfaces were changed. This change is associated with a change of content and the morphology of sigma phase.

The Effect of Long-Term Annealing on Microstructure of Aluminide Coatings Deposited on MAR M200 Superalloy by CVD Method

The paper presents the influence of long-term heat treatment on aluminide coating. The MAR M-200 nickel superalloy was use as base material. The aluminide coating was deposited in low-activity chemical vapour deposition process using Ion Bond BPX Pro 325s device with following parameters: temperature 1040°C, time 12 hours, pressure 150 mbar. The samples (14 mm diameter) were annealed at 1020°C in vacuum for 12, 16 and 20 hours respectively. The XRD phase analysis and SEM microstructural observation with EDS analysis were conducted. The phase composition analysis showed that after deposition the NiAl phase is a main component of the coating. After the 20-hour-long annealing presence of Ni3Al phase in the coating was observed. Changes in structure of coatings and Al content during heat treatment were detected as well. The maximum duration of heat treatment performed for Ni superalloy with aluminide coating without significant changes in coating phase composition and microstructure is 16 hours.

Retraction: Effect of Long-Term Annealing on the High-Temperature Strength of Ferritic Stainless Steels with Intermetallic Precipitates

Retraction: Effect of Long-Term Annealing on the High-Temperature Strength of Ferritic Stainless Steels with Intermetallic Precipitates

Effect of long term annealing on the microstructure and tensile properties of hpdc AZ91 Mg alloy

Abstract This work is aimed to obtain the effect of long term annealing (LTA) on the tensile properties and on the microstructure of a high pressure die cast (hpdc) AZ91 Mg alloy. Tensile tests were performed on as-cast and LTA for 1000 h at 150 and 200 °C hpdc castings and the effect of LTA on the tensile properties such as yield strength (YS), ultimate tensile strength (UTS), ductility and fracture strain (FS) are confirmed. Additionally, explanations on micro failure mode of the material are presented to explain the influence of different micro features on failure of the material. The average size, area fraction and clustering tendency of β m (massive) and β c+d (continuous + discontinuous) Mg 17 Al 12 particles are quantified and their effects on LTA are obtained. The results confirm that the UTS, YS, ductility and FS are mainly influenced by the area fraction, size distribution and spatial arrangement of β particles.

Effect of long-term annealing upon antiflake treatment on the structure and impact toughness of the 40KhGM steel

The long-term annealing used for the removal of hydrogen from forgings affects the structure, impact toughness, and the fracture mode of the steel. It stimulates the fragmentation and spheroidization of cementite plates and the polygonization of ferrite. The impact toughness increases by a factor of 2–10, depending on the sulfur content. The structure changes occurring upon annealing increase the resistance of the metal to flake growth.

Effect of long-term annealing on accumulation of impurities

The occurrence of changes in impurity accumulation after a long-term annealing preceding the in-diffusion of impurities is shown experimentally. Atoms of Au as acceptors affecting the resistivity and photoconductivity decay time were used as indicators in studies of these changes.

Growth and Properties of V-Doped HgSe Crystals

HgSe〈V〉 crystals with a vanadium concentration ranging from 1024to 1026m–3were grown, and their transport properties were investigated between 77 and 400 K in magnetic fields of up to 12.73 kA/m. The effect of long-term annealing in Se vapor on the electron concentration and mobility in the crystals was studied. The n(NV), μ(T), and RH(T) data obtained before and after annealing suggest that the V dopant produces a resonance donor level in the conduction band of HgSe at EV≃ 0.250–0.260 eV.

Structure, Homogeneity and Properties of Thermoelectric Materials Based on Ternary Solid Solutions of Bismuth and Antimony Chalcogenides

Ternary solid solutions BixSb1-xTe and especially Bi2Te1-ySey grown by vertical zone melting have the tendency for dendrite liquation. It causes considerable chemical inhomogeneity of the material and multicomponent structure. The effect of long-term annealing at 380–400°C on microstructure, phase composition and properties of structural components has been studied. It was shown that proper growth regime provides ingots with oriented column structure and good texture, which maximizes thermoelectric properties along the growth axis.

The Crystalline-Amorphous Transformation in Natural Zirconolite: Evidence for Long-Term Annealing

ABSTRACTDose-age relationships have been determined by analytical and transmission electron microscopy (AEM and TEM) for the onset dose and critical amorphization dose of a suite of natural zirconolites. Together with a preliminary investigation of the thermal histories of the zirconolite-bearing rocks, the results indicate that valid estimates of D0 (intercept dose at t = 0) and K (annealing rate constant) are obtained and that the host rocks experienced temperatures on the order of 100-200 °C averaged over time. The natural samples are therefore best suited as radiation damage analogues for waste forms stored under deep borehole conditions where temperatures of 100-450 °C are expected. Our results indicate that the critical amorphization (or saturation) dose of zirconolite will increase by a factor of approximately 2 or more as a result of storage at elevated temperature. The effect of long-term annealing on the critical amorphization dose is only important for times in excess of 107-108 years due to the low annealing rate constant of 10−9/yr.

The effects of long-term annealing on superconducting properties in the Bi-Sr-Ca-Cu-O system

The effect of long-term annealing on the relative proportions of the low- and high-Tc phases present in the Bi-Sr-Ca-Cu-O system was examined by resistivity and ac susceptibility measurements. The zero-resistivity offset was found to increase from 50 to 68 K and the susceptibility measurements showed the disappearance of the low-Tc , 63-K phase with the enrichment of the high-Tc , 110-K phase as a result of the annealing treatment. Also, the onset of diamagnetism of the high-Tc phase was enhanced by 3 K due to prolonged annealing. The high-Tc phase thus formed is poorly crystallized as determined by the x-ray diffraction patterns. Some impurities are observed in both x-ray diffraction patterns and scanning electron microscopy pictures and are assigned to the low-Tc , Sr, and Bi-doped Ca2CuO3 phases. This study shows that a complex ac susceptibility measurement technique can be a very powerful tool for studying the equilibrium superconducting phases present at a particular temperature in a multicomponent system such as Bi-Sr-Ca-Cu-O.

Damage effects and recovery in LiF:Mg, Ti thermoluminescent dosimeters after long-term annealing at 400°C

The effect of long-term annealing at 400°C was investigated on unirradiated and pre-exposed TLD 600 and TLD 700 in the dose range from 10 3 to 10 6 R and up to annealing periods of 1000 h. The lower response of high pre-exposed dosimeters may be restored partially depending on the annealing period and the amount of damage. In addition to the recovery of radiation-induced damage a thermally stimulated damage in unirradiated dosimeters was also observed resulting in a decrease of the dosimeter response for annealing periods above 100 h.