Initial Stage Of Aging Research Articles

Влияние старения на микроструктуру, фазовый состав и микротвердость высокоазотистой аустенитной стали

The authors studied the effect of duration of age hardening at the temperature of 700 °C on the microstructure, phase composition and microhardness of high-nitrogen Fe-23Cr-17Mn-0.1C-0.6N (wt. %) steel. The study showed that age hardening at the temperature of 700 °C for half an hour causes the complex of phase transformations: the decomposition of δ-ferrite (with the formation of σ-phase and austenite) and the formation of cells of discontinuous decomposition on the austenitic grains boundaries (the formation of particles based on the chromium nitride Cr 2 N and the depletion of austenite by interstitials). After age hardening for more than 10 hours, besides the discontinuous decomposition of austenitic grains, a homogeneous (continuous) precipitation of chromium nitride occurs in those austenitic grains, which have not undergone discontinuous decomposition in the initial stages of aging. With an increase in the aging duration up to 50 hours, the authors observed the growth of decomposition cells in austenitic grains and the formation of mixed structure. Such structure consisted of austenite grains, which underwent discontinuous decomposition with the formation of lamellar precipitations of chromium nitride in austenite; austenitic grains with the dispersed particles formed by the mechanism of continuous decomposition; and the grains with σ-phase, chromium nitrides, and austenite formed as a result of the high-temperature ferrite decomposition during aging. The aging caused the increase in the microhardness, which value depends on the mechanism of precipitation hardening - continuous or discontinuous decomposition in austenite or the precipitation of intermetallic σ-phase and chromium nitrides plates in the grains of high-temperature ferrite.

Synthesis of nickel hydroxide in the presence of acetate ion as a «soft» ligand for application in chemical power sources

Nickel hydroxide is widely used as the active material in chemical power sources. The formation mechanism of nickel hydroxide includes two fast phases of the formation of an initial amorphous particle and slow aging (crystallization) stage. Characteristics of nickel hydroxide can be improved by slowing down the first stage through the reaction of nickel cation with «soft» ligand and formation of a weak complex. It is proposed to use acetate ion as a «soft» ligand, which forms a complex with Ni2+ without the outer sphere. The influence of acetate ion on the crystal structure, particle morphology and electrochemical properties of nickel hydroxide chemically precipitated at high supersaturation using nickel sulfate in the presence and absence of sodium acetate is studied. The crystal structure of the samples is studied by means of X-ray diffraction analysis and sample morphology – by means of scanning electron microscopy, electrochemical properties – cyclic voltammetry. A comparative analysis of the characteristics of the samples prepared in the presence and absence of sodium acetate is carried out. The results of XRD analysis revealed that synthesis in the presence of acetate ion leads to the formation of a bi-phase system that contains low crystallinity β-Ni(OH)2 and α-Ni(OH)2. This also leads to a higher content of smaller particles with a larger surface area. The comparative analysis of electrochemical characteristics revealed the formation of a more active samples in the presence of acetate ions, which predominantly behaves like the α-form. The sample activity increased during cycling. Synthesis in the presence of acetate ion results in the increase of specific discharge peak current (equivalent to electrochemical activity) by 1.93 times, in comparison to the sample synthesized under the same condition but in the absence of acetate ions

Effect of Cu Contents on Nanocluster Formation and Two-Step Aging Behavior in Al–Mg–Si Alloys

The effect of Cu contents on nanocluster formation and the two-step aging behavior of Al–Mg–Si alloys was studied based on hardness, DSC and TEM results. The activation energies for the formation of Cluster (1) were 61.6, 70.3 and 92.9 kJ/mol for Cu-free, 1Cu (0.1 mass% Cu-added) and 3Cu (0.3 mass% Cu-added), respectively. It was confirmed that hardness increased slowly with increasing Cu content during natural aging for 3.6 ks. These results suggest that the formation kinetics of Cluster (1) decrease due to the vacancy trapping phenomenon, because of the strong interactions of the Cu-vacancies. Meanwhile, the effect of the formation of nanoclusters by Cu addition on the two-step aging behavior at 170 °C during natural aging was analyzed. Hardness at the initial stage of the two-step aging increased with increasing Cu contents. This was caused by the suppression of Cluster (1) formation during natural aging by the Cu additions. Based on TEM results, at the peak hardness of the two-step aging, the number density of precipitates was increased by increasing Cu contents, due to the suppression of nanocluster formation during natural aging. Nanocluster formation behavior by DSC, two-step aging behavior based on hardness results and precipitation observation at the peak hardness using TEM. Two types of nanoclusters were analyzed using DSC based on Gaussian function method in Al–Mg–Si alloys. The formation of nanoclusters is suppressed during natural aging by Cu additions. Also, the hardness is clearly increased by Cu addition at the initial stage of two-step aging at 170 °C after natural aging for 3.6 ks. Based on TEM results, the number density of precipitates was increased by increasing Cu contents at the peak hardness of the two-step aging due to the suppression of nanocluster formation during natural aging.

Quality Index of Tensile Property on Porosity Variation in A356 Casting Alloys upon T6 Treatment

The contribution of porosity variation affecting the tensile properties of A356 aluminium alloys was investigated in terms of the variations in the quality index of tensile properties as well as the strength coefficient and strain-hardening exponent associated with the T6-treatment. The test specimens were prepared using a low-pressure die-casting and subsequent T6-treatment, and the contribution of microporosity, microstructural features and strain-relating factors to quality index was quantitatively evaluated using a modified constitutive model. The quality index of A356 alloys increases gradually with the lapse of ageing time upon T6-treatment, which increases significantly at the initial ageing stage with rise in the ageing temperature. Additionally, the quality index of A356 alloy primarily depends on the porosity variation with power law relationship, irrespective of its state, i.e. solutionised or artificially aged. Theoretically, the strength coefficient directly determines the nominal level of quality index. The overall dependence of quality index on porosity variation is weakened with increasing tensile strain, but it significantly depends upon the porosity variation for lower values of the strain-hardening exponent. The age hardening arises an explicit transition on fracture path by the damage evolution of eutectic Si particles, which can influence the overall level of quality index through a change in the effective void area fraction, with the microporosity variation by pre-existing micro-voids in casting alloys. A wide deviation on quality index of A356 casting alloy depends practically upon the microporosity variation. Additionally, the nominal level of quality index is influenced by the damage evolution of eutectic Si particles as well as the variation of strength coefficient and strain-hardening exponent by age hardening on T6-treatment. The theoretical approach by constitutive model can quantitatively describe the individual contributions of the strength coefficient and strain-hardening exponent to the overall level of quality index, including the microstructural features such as the area fraction and distribution aspect of micro-voids and eutectic Si particles.

Multiple Influences of Molybdenum on the Precipitation Process in a Martensitic PH Stainless Steel

Molybdenum has been found to influence the complex precipitation process in a martensitic precipitation hardening stainless steel during aging at 475 °C in several different ways. Three steels with different Mo content (0, 1.2 and 2.3 at.%) were investigated. Studies of the microstructure were performed with atom probe tomography and energy filtered transmission electron microscopy. It is shown that, at the initial stage of aging, a faster nucleation of Cu-rich clusters takes place with increasing Mo content. The Cu-clusters act as precipitation sites for other solute elements and promote the nucleation of Ni-rich phases. During further aging, a higher Mo content in the material instead slows down the growth and coarsening of the Ni-rich phases, because Mo segregates to the interface between precipitate and matrix. Additionally, Mo promotes decomposition of the matrix into α and α′ regions. After longer aging times (>40 h) quasicrystalline Mo-rich R′ phase forms (to a greater extent in the material having the highest Mo content). The observations serve to understand the hardness evolution during aging.

Precipitation response and hardening behaviors of Fe-modified Ti5553 alloy

Abstract Ti5553−xFe (x=0.4, 1.2, 2.0, wt.%) alloys have been designed and fabricated through BE (blended element) sintering to investigate the effect of Fe-addition on athermal ω-phase transformation, α-phase evolution and age hardening behavior. The results show that the formation of athermal ω-phase is fully suppressed in water-quenched specimens when Fe-addition is up to 2 wt.%. The relevant timescales of α formation during initial stages of aging indicate that incubation time increases with Fe-addition. Further aging results in continuous nucleation and growth of α-phase but finer intragranular α lamellae exhibit in Ti5553−2Fe alloy. In addition, the width and extent of grain boundary α-film increase slightly with incremental Fe-addition, especially in furnace cooling condition. Result of Vickers hardness manifests that Fe-addition leads to a strong hardening effect in both solution and aging treatment. The solid solution strengthening is quantitatively estimated by ab initio calculation based on the Labusch−Nabarro model. The evolution of α-precipitate is rationalized by Gibbs free energy. The prominent hardening effect of Ti5553−2Fe alloy is attributed to both large lattice misfit of β-matrix and fine α-precipitate distribution.

Sensitivity of a Number of Physical Properties to Fixation of the Initial Stages of Aging of Fe–14.5% Mo Alloy

Regularities of the change in physical properties (coercive force, electrical resistance, and internal friction) of the Fe–14.5% Mo alloy depending on temperature and time of aging after tempering from the single-phase area were studied. It was shown that the internal friction possesses the highest sensitivity to fixation of the initial stages of aging as compared with other studied physical properties. Data on physical properties are comparable with the peculiarities of the phase-structural transformations observed during aging. The aging modes providing the highest values of the coercive force, which limits the practical value of the studied alloy as a high-coercivity material with the average magnetic energy value, were established.

A Simple Analytical Model of Capacity Fading for Lithium–Sulfur Cells

A simple ageing model is proposed for the fading of lithium–sulfur (Li–S) cell capacity with the number of cycles. The model could be applied for the ageing description of cells with an unknown internal structure in a wide range of engineering applications. Cycle profile that patterns with the real-life operation of cells is proposed. Thus, the degradation of the cell is simultaneously influenced by the 100% depth-of-discharge cycling and the cell staying at a charged state. The proposed model is described by the differential equation considering that the decrease of cell capacity per cycle is proportional to the product of cycle number and the charge available to be discharged within the appropriate cycle. The model covers the degradation processes dominant in the initial stage of ageing, where the cell capacity decreases from 100% to about 25% of its initial value. The solution of the proposed differential equation is an analytical function that requires only three fitted parameters. The dependence of model parameters on the charge/discharge current rate is shown for studied Li–S cells. Possible sources of degradation, such as the decrease of electrode effective area and the decrease of potential barrier on the electrode/electrolyte interface, are determined from the evaluation of the coulombic efficiency of the charge/discharge process.

Evaluation of intergranular corrosion susceptibility of Super304H steel after being aged at 600°C

The susceptibility to intergranular corrosion of as-received and 600°C aging-treated new austenite heat-resistance Super304H steel was investigated by double loop electrochemical potentiodynamic (EPR) test. Experimental results indicated that the as-received Super304H steel possesses lower tendency of intergranaular corrosion. With the increase of aging time, intergranular corrosion susceptibility of Super304H steel increases. Intergranular corrosion of Super304H steel occurs due to the precipitation of Cr23C6 along grain boundaries. At the initial stage of aging, the rapid precipitating behavior of Cr23C6 leads to the rapid increase of intergranlar corrosion susceptibility. The amount of Cr23C6 precipitates increases with the extension of aging time, and the intergranular corrosion susceptibility of Super304H steel increases accordingly. The extent of intergranular corrosion change is related to the precipitating rate of Cr23C6. ()

Chemical and rheological evaluation of aging properties of high content SBS polymer modified asphalt

High content SBS polymer modified asphalt (HCPMA) is now widely employed in Open-Graded Friction Course (OGFC), but its aging behavior has not yet been well understood due to its high polymer content and consequently high construction temperature. In this study, HCPMA were aged at various temperatures and durations in the laboratory and the chemical and rheological evolutions during aging were tracked using Gel Permeation Chromatography (GPC), Fourier Transform Infrared (FTIR), dynamic shear oscillatory test, master curve and multiple stress creep and recovery test. GPC and FTIR results show that generally the polymer degradation happens at the initial stage of aging. Rheology tests highlight an interesting finding that aging will push the HCPMA to a less elastic end, which is due to the softening effects of polymer degradation. It is found that among all aging conditions, HCPMA yields the least elastic response after the standard Pressure Aging Vessel aging. Moreover, Principal Component Analysis shows that the 9 popular parameters employed in this study (such as modulus, phase angle, Jnr3.2 and etc.) have a lot in common and can be explained by two variables: asphalt oxidation level and SBS content. By using these two variables, the evolution of HCPMA modulus and phase angle after aging can be well predicted with an exponential regression and a linear regression, respectively. The research findings provide insights to better understand the aging properties of HCPMA.

Aging behavior of nano SiC particles reinforced AZ91D composite fabricated via friction stir processing

AZ91D magnesium alloy matrix composites reinforced with nano SiC particles (n-SiCp) was fabricated by Friction Stir Processing, and the effects of n-SiCp on the β-Mg17Al12 phase precipitation at 180 °C as well as the age hardening response of AZ91D were investigated by X-ray diffraction, optical microscopy, scanning electron microscopy, transmission electron microscopy, and micro Vickers hardness measurements. The results show that, with the addition of n-SiCp, the microstructure of AZ91D after FSP was greatly refined, the texture strength was decreased, and the age hardening efficiency became inferior. As n-SiCp can efficiently block the migration of grain boundaries and grain growth, the composite exhibited a higher microstructure stability at elevated temperatures, and the discontinuous precipitation of β-Mg17Al12 phase that dominated the age process of AZ91D at 180 °C was remarkably restricted in the composite. Besides, n-SiCp promoted the continuous precipitation of β-Mg17Al12 phase and the precipitation rate in the composite was faster at the initial aging stage, but on further aging the precipitation rate became gradually slower than that in the AZ91D. The underlying mechanisms for the different age precipitation behavior and age hardening response were also discussed.

Influence of Natural Aging Time and Mg/Si Ratio (Mg + Si = 1.3 mass%) on the Two-Step Aging Behavior in Al–Mg–Si Alloys

Two-step aging with the different natural aging times and chemical compositions was carried out in Al–Mg–Si alloys to investigate the clustering and two-step aging behavior. The activation energies of cluster formation through the Kissinger method were analyzed as 69.4, 67.3 and 73.8 kJ/mol for the 9M4S, 6M6S and 3M10S, respectively. A similar hardness was identified for short-term natural aging for 3.6 ks regardless of the Mg/Si ratio. On the other hand, a lower hardness was identified in the 3M10S (Mg/Si = 0.3) than in 9M4S (Mg/Si = 2.5) and 6M6S (Mg/Si = 1) for long-term natural aging for 4838.4 ks. The hardness increase during the two-step aging was due to the formation of a β″ phase during artificial aging based on structure analysis of high resolution transmission electron microscope images. There was a hardness decrease at the initial stage of the two-step aging at 170 °C in the case of long-term naturally-aged specimens. The hardness decrease was caused by the partial dissolution of the Mg–Si co-cluster, which was influenced by the Mg/Si ratio. Meanwhile, the hardness increase during two-step aging was promoted for 6M6S and the higher number density of the β″ phase was confirmed.

Mn Promotes the Rate of Nucleation and Growth of Precipitates by Increasing Frenkel Pairs in Fe-Cu Based Alloy

The Fe-1.0Cu (at. %) and Fe-1.2Cu-2.2Mn alloys aged at 450 °C for 0.25 h, 1 h, 2 h, and 16 h after solution treatment at 900 °C for 2 h are investigated to reveal the role of the addition of Mn on the Cu precipitates in Fe-Cu based alloys. Density functional theory (DFT) total energy calculations on point defects and their influence on Cu precipitates are also performed to understand the nucleation and growth of Cu precipitates. Experiments show that addition of Mn can slightly increase the aging peak hardness by 10 HV; by using atom probe tomography (APT) and optical microscopy, we identify that the increase in hardness derives from both grain refinement and the increase of number density of precipitates. DFT calculations show that Mn increases the formation possibility of Frenkel pairs, i.e., atomic vacancy and self-interstitial atoms, and these two types of defects both serve as nucleation sites of Cu precipitates, resulting in the increase of the nucleation centers number density, which is well consistent with our APT experiments on the very initial stage of aging. Moreover, calculated results show that Mn increases the density of atomic vacancy and promotes evolution rate of Cu precipitates, which accounts for our APT experiments that precipitates in Fe-Cu-Mn grow more quickly than that in Fe-Cu does. Finally, we also discuss the relationship between Mn content in reactor pressure vessel steels and its irradiation damage effects.

The Influence of Long-term Ageing on the Microstructure of Sanicro 25 Steel

Sanicro 25 (22Cr25NiWCoCu) is a newly developed austenitic stainless steel used in the boiler pressure superheaters and reheaters with ultra-supercritical high-efficient parameters. The paper presents the results of microstructure testing and secondary phase separation processes after 20,000 h ageing at 700 and 750 °C. In the initial stage of ageing, the precipitation of numerous very small M23C6 chromium carbides and Laves phase were observed. The long-term ageing related to temperature revealed the existence of secondary phases: M23C6, MX, NbCrN, Laves phase and σ phase. The test results presented in the paper are part of the developed material characteristics to be used for predicting the service life of the material of components operated under creep conditions.

Fabrication of Stable Carbon Nanotube Cold Cathode Electron Emitters with Post-Growth Electrical Aging.

We fabricated carbon nanotube (CNT) cold cathode emitters with enhanced and stable electron emission properties and long-time stability with electrical aging as a post-treatment. Our CNT field emitters showed improved electrical properties by electrical aging. We set the applied bias for effective electrical aging, with the bias voltage defined at the voltage where Joule heating appeared. At the initial stage of aging, the electron emission current started to increase and then was saturated within 3 h. We understood that 5 h aging time was enough at proper aging bias. If the aging bias is higher, excessive heating damages CNT emitters. With the electrical aging, we obtained improved electron emission current from 3 mA to 6 mA. The current of 6 mA was steadily driven for 9 h.

Evolution of the Crystal and Electronic Structures of the RBa2Cu3O6 + δ Cuprates in Annealing

The crystal structure and the magnetic properties of the HTSC cuprates YBa2Cu3O6 + δ, Y1 ‒ xCaxBa2Cu3O6 + δ, and Nd1 +xBa2 –xCu3O6 + δ (x = 0.2) with the structure of a layered perovskite are studied. The well-known aging effect detected in these HTSC materials during storage under standard conditions, namely, an increase in their critical temperature Tc and a decrease in lattice parameter c in time, is investigated. Using YBa2Cu3O6 + δ as an example, we show that the dependence of c on the oxygen content undergoes the following changes in time: (1) the negative slope of the dependence with respect to axis δ increases and (2) nonlinearity appears and grows in time according to a quadratic law. The first type of changes is explained by an increase in the valence of copper ions, which is accompanied by a decrease in their radius. The second type is explained by the electrostatic interaction of structural CuO2 planes due to the accumulation of electron holes, which come from CuOδ planes, in them. The calculation of the second type of changes in parameter c in the YBa2Cu3O6 + δ cuprate exhibits good quantitative agreement with the experimental data. The second-type changes in the Y1 –xCaxBa2Cu3O6 + δ compound (hole doping of CuO2 planes) turn out to be identical to those in YBa2Cu3O6 + δ. However, the differently directed (in time) changes in lattice parameter c in Nd1 +xBa2 –xCu3O6 + δ indicate that the CuO2 planes in the neodymium cuprate are doped by electrons at the initial stage of aging. However, when these planes are saturated with holes in time, the type of doping changes from n to p without a noticeable change in the crystal structure, which has been considered to be impossible for layered cuprates to date.

Microstructure and mechanical properties of the (Fe,Ni)Al-based alloy produced by SLM and HIP of spherical composite powder

The microstructure and properties of spherical composite powders produced from the β-(Fe, Ni)Al-based alloy by plasma rotating electrode process (PREP) using a steel-shelled electrode were studied. Parameters of the selective laser melting (SLM) mode (laser power density, laser intensity, scan speed and regime) were optimized to ensure the minimal porosity of < 0.08% as well as the absence of cracks or structural defects. Pore distribution and pore volume fraction in the fabricated samples were determined by 3D microCT visualization. The evolution of structural transformations in the matrix of the as-SLM (Fe, Ni)Al alloy was observed as the alloy was heated to the aging temperatures of 850 and 1250 °C. At 1250 °C, the secondary α-Fe precipitates are transformed to coherent cuboids with a cube-on-cube orientation relationship limited by the {100} plane. The in situ transmission electron microscopy (TEM) studies of structural phase transformations occurring upon heating in the temperature range of 20–850 °C demonstrated that coherent α-precipitates with a cubic morphology are homogenously nucleated via the mechanism of spinodal decomposition of an oversaturated solid solution of the B2 phase. Segregation of the pre-precipitation zones < 3 nm in size was observed at 450–650 °C. At the initial stage of ageing, α-Fe precipitates have a near-spherical shape. The positive effect of ageing at 850 and 1250 °C on properties of the alloy produced by SLM of spherical composite powders was demonstrated. Ageing at 1250 °C enhances the ultimate compressive strength (σb) and ductility (ε) from σb = 1490 ± 34 MPa at ε = 1.2% to σb = 1650 ± 41 MPa at ε = 8.0%. The maximum mechanical properties were observed in the samples produced by HIP: conditional ultimate compressive strength: 2120 ± 60 MPa (which corresponds to the true ultimate compressive stress σb = 1765 ± 50 MPa) and plastic yield ε = 16.25% (e = 0.1774) at an offset yield point (true yield stress) σ0.2 = 872 ± 21 MPa. Thermomechanical properties of the (Fe,Ni)Al- based alloy at 873–1373 K was studied. The temperature-force dependence of the steady-state creep rate has been analyzed. The true yield stress equal to 566 MPa was measured at 873 K, logarithmic strain rate 0.001 s−1, and degree of induced plastic strain 0.2%. It was shown that high-temperature mechanical properties of (Fe,Ni)Al- based alloy has intermediate values in between intermetallic alloy Ni41Al41Cr12Co6 and Fe-Ni-Gr-Al alloy (EP747).

Spectral properties of AlCrNO-based multi-layer solar selective absorbing coating during the initial stage of thermal aging upon exposure to air

A spectrally selective Cr/AlCrN/AlCrNO/AlCrO multi-layer absorber coating has been designed and deposited on stainless steel substrates by the cathodic arc ion plating technique. The spectral properties of the multi-layer coating during the initial stage of thermal aging in air were investigated with the aim of achieving a basic understanding of its relation to microstructure. The composition, structure and surface morphology of the coatings were characterized using XRD, SEM, XPS, TEM and AFM, while the optical properties of the coatings were measured by spectrophotometers. The experimental results indicate that the multi-layer coating with a high solar absorptance of 0.90 and a relatively low emittance of 0.15 are obtained through parameter optimization. The structure analysis suggests that the as-deposited AlCrN and AlCrNO layers, acting as the main absorbers, are consisted of the AlN, Cr2N and AlN, CrN, Cr2N nanocrystallites embedding in amorphous matrix, respectively. While the AlCrO layer, acting as the anti-reflection layer, is consisted of mainly amorphous. After annealing at 500 °C for 2 h in air, a solar selectivity of 0.94/0.12 was achieved while the thermal emittance attained 0.25 at 500 °C. Based on the microstructural analysis, the enhancement in absorptance of the multi-layer AlCrNO-based coating during the initial stage of thermal aging could be attributed to the decomposition of Cr2N nanocrystallites and the recrystallization of the AlCrN and AlCrNO layers. While the enhanced emittance after annealing can be ascribed to the decomposition of the macro-droplets and the decrease of surface roughness. These results could provide new insights into rational use of the muti-layer coatings and spectral properties tuning of solar-selective functional multi-layer coatings and thus promote the development of coatings for photo-thermal conversion at high temperatures.

Noise test system of rotating machinery in nuclear power station based on microphone array

Rotating machinery plays an important role in all walks of life. Once the equipment fails, equipment maintenance and shutdown will cause great social harm and economic losses. Equipment safety operations at nuclear power stations have always been of top priority. It is prone to noise when the equipment is out of order or aging. Failure to find or develop equipment at the initial stage of equipment failure or ageing will pose a serious threat to the safety of the plant’s equipment. In this paper, sound imaging diagnosis technology is applied as a supplementary method to the condition monitoring and diagnosis system of rotating machinery in nuclear power stations. It provides a powerful guarantee for the condition monitoring and fault diagnosis of rotating machinery in nuclear power stations.

EFFECT OF DISPERSED PHASE COMPOSITION AND DISTRIBUTION AFTER AGING ON FORMABILITY OF D16 ALUMINIUM ALLOY SHEETS

The relevance of this paper is connected with rising accuracy requirements to stamped parts made of aged aluminium alloys applied also for layered composite making. These requirements can be met by controlling the sheet blank structure, and particularly its phase composition. The paper provides experimental results obtained when studying the effect of aging modes on the composition, dispersed phase distribution pattern and formability of sheet samples made of D16 (AA2024) aluminium alloy. Heat treatment consisted in quenching from a temperature of 500 °С into room temperature water and further aging: natural aging during 7 days, artificial aging at temperatures of 50, 100, 150 and 200 °С and holding at each temperature during 15, 30, 60, 120 and 240 minutes. The quantitative method is proposed to evaluate the dispersed phase distribution pattern by microstructure pictures. Formability was evaluated using the stamping number, i.e. a proof/ultimate factor. It was found that the stamping number rises as the aging temperature and holding time are increased, which shows the lower alloy applicability for sheet stamping operations. No dispersed phase was formed when aged at t = 50 °С in both optical metallography and scan electron microscopy cases. The non-uniformity of dispersed phase distribution inside a grain rises at initial aging stages with a holding time less than 1 hour at 100, 150 and 200 °С and decreases with a further increase in the holding time up to 4 hours. No correlation was observed between the uniformity of phase distribution and the stamping number. The chemical composition of phases has a greater effect on the formability and changes depending on a heat treatment mode: annealing and natural aging primarily lead to the θ and S phase precipitation; aging at temperatures below 150 °С with a holding time less than 1 hour lead to the θ, S and T phase precipitation; θ phase appears after aging at temperatures over 150 °C with long holding times.