Effect Of Aging Heat Treatment Research Articles

시효처리에 따른 Ti-6Al-4Fe-0.25Si 합금의 미세조직 변화

The effect of aging heat treatment on microstructure evolution of the Ti-6Al-4Fe-0.25Si alloy with an initial microstructure of an elongated alpha was investigated. Aging treatments of the samples were carried out at 550°C for up to 100 hours. The microstructure of the 5 hours heat-treated sample consisted of alpha grains, beta matrix and some TiFe intermetallic compounds that were precipitated from the beta matrix. Increasing the aging time to 10 hours, most of the beta matrix was decomposed to very fine alpha grains (~ 0.5 μm) and TiFe, and thus the volume fraction of the beta matrix was significantly decreased. EBSD analysis revealed that newly formed tertiary-alpha-grains in the vicinity of TiFe had high angle boundaries with respect to the primary and secondary alpha grains. As a result of these phase transformations during aging, the fraction of the alpha/alpha grain boundary was increased while that of the alpha/beta phase boundary was decreased. (Received March 30, 2012)

Artificial Neural Network (ANN) Approach to Hardness Prediction of Aged Aluminium 2024 and 6063 Alloys

Abstract In this study, the effect of aging heat treatment on the hardness of AA 2024 and AA 6063 aluminum alloys was investigated by experimental and an Artificial Neural Network (ANN). AA 2024 and AA 6063 aluminum alloys were solution treated at two different temperatures of 490° C and 520° C. Then both samples were cooled to room temperature. After this process, the samples were aged at three different temperatures (140° C, 180° C, 220° C) for ten different periods of time (2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 h.). The experimental results were trained in an ANNs program, and the results were compared with experimental values. It is observed that the experimental results coincided with the ANNs results.

Effects of Aging Heat Treatment on the Microstructure of Ti-Nb and Ti-Nb-Sn Alloys Employed as Biomaterials

The mechanical behavior of β titanium alloys applied as orthopedic biomaterials depends directly on their microstructural features, and can be improved by tailoring the microstructure through the control of their phase transformations. The aim of this investigation is to discuss phase transformations during the aging heat treatment of β Ti-30Nb and β Ti-30Nb-2Sn alloys and to correlate microstructure and mechanical behavior. The results of high temperature XRD experiments showed decomposition of orthorhombic α” phase, followed by the precipitation of ω and α phases. The mechanical behavior of Ti-Nb and Ti-Nb-Sn alloys was found to be highly sensitive to the microstructural changes caused by the addition of Sn and by heat treatments.

Effects of double aging heat treatment on the microstructure, Vickers hardness and elastic modulus of Ti–Nb alloys

Abstract Aging heat treatment can be a good way to optimize mechanical properties, changing the microstructure, and hence, the mechanical behavior of Ti alloys. The effects of aging heat treatments on β-type Ti–30Nb alloy were investigated to evaluate the kinetics of α″ → α + β transformation. The results obtained from differential scanning calorimetry and high-temperature X-ray diffraction experiments indicated the complete decomposition of orthorhombic α″ phase at close to 300 °C, followed by α phase precipitation at 470 °C. The aging heat treatments also enabled us to observe a transformation sequence α″ → β + ω → β + ω + α, indicating martensite decomposition and ω phase precipitation at 260 °C after 2 h, followed by α phase nucleation after heating at 400 °C for 1 h. The elastic modulus and Vickers hardness of Ti–30Nb alloy were found to be very sensitive to the microstructural changes caused by heat treatment.

The Effect of Aging Heat Treatment on the Sliding Wear Behavior of Cu-Al-Fe-(x) Alloys

Wear behaviour of aged casting Cu-Al-Fe-Be and Cu-Al-Fe-Ni aluminum bronzes was studied in this paper. The microstructures, mechanical properties of hardness and tensile strength, were evaluated experimentally. The friction and wear resistance, and the electrical resistivity of the materials were assessed. The results show that mechanical properties of the Cu-Al-Fe-Be alloy have been improved by solution treatment at 950°C for 120 min followed by aging at 350°C for 120 min, whilst the most suitable heat treatment for the Cu-Al-Fe-Ni alloy was solution treatment at 950°C for 120 min followed by aging at 450°C for 120 min. In the wear testing, the as-cast alloys was dominated by abrasive wear, and the increase in load and sliding velocity, the adhesive wear and oxidation wear dominated. The experimental results also showed that the Cu-Al-Fe-Be alloy possessed higher hardness and tensile strength, lower friction coefficient and lower wear rate compared to the Cu-Al-Fe-Ni alloy.

The Effect of Aging Heat Treatment on the Mechanical Properties of Cu-Al-Fe-(x) Alloys

Alloys were produced by casting of Cu-Al-Fe-Be and Cu-Al-Fe-Ni aluminum bronzes and aged. The microstructures and mechanical properties were evaluated. The results indicated that solution and aging treatment can significantly improve the plasticity of Cu-Al-Fe-Be and Cu-Al-Fe-Ni, while the strength and hardness remained in the quenched level. Extending the aging time can effectively enhance the mechanical properties of alloys, and the longer the aging time, the higher the electric resistance of alloys. According to the results, the mechanical properties of the Cu-Al-Fe-Be alloy can be improved remarkably by solution treatment for 120 min at 950°C, followed by aging treatment for 120 min at 350°C, and quenched. While the most suitable heat treatment for the Cu-Al-Fe-Ni alloy was solution treatment 120 min at 950°C, followed by aging for 120 min at 450°C, and quenched. The experimental result also suggested that the Cu-Al-Fe-Be alloy possessed higher hardness and tensile strength compared to the Cu-Al-Fe-Ni alloy.

Effect of Aging on the Toughness of Austenitic and Duplex Stainless Steel Weldments

In the present study, the effect of aging heat treatment at 650, 750, and 850°C on the impact toughness of 316L austenitic stainless steel, 2205 duplex stainless steel and their weldments has been investigated. Welding process was conducted using the TIG (tungsten inert gas) welding technique. Instrumented impact testing, at room temperature, was employed to determine the effect of aging treatment on the impact properties of investigated materials. Aging treatment resulted in degradation in the impact toughness as demonstrated by the reduction in the impact fracture energy and deformation parameters (strain hardening capacity, fracture deflection, and crack initiation and propagation energy). The degree of embrittlement was more noticeable in duplex stainless steel parent and weld-metal than in 316L stainless steel and became greater with the increase of aging temperature. The degradation in impact toughness was discussed in relation to the observed precipitation of the intermetallic sigma phase in the microstructure of the stainless steel weldments and the corresponding fracture surface morphology.

YAŞLANDIRMA ISIL İŞLEMİNİN 7075 ALÜMİNYUM ALAŞIM MALZEMELİ DİKDÖRTGEN PLAĞIN BURKULMA YÜKÜ ÜZERİNE ETKİLERİ

Bu calismada, yaslandirma isil isleminin 7075 aluminyum alasimindan yapilan dikdortgen plaklarin burkulma yuku ve mekanik ozellikleri uzerine etkileri incelenmistir. Plaklar icin sinir sarti iki kenari basit mesnetli ve diger iki kenari serbest olarak alinmistir. Yaslandirma isil islemi sirasiyla, 480oC'de 1 saat solusyona alma, suda hizli sogutma ve 130oC sabit sicaklikta farkli zaman araliklari kullanilarak gerceklestirilmistir. Yapilan calismada temel degisken olarak yapay yaslandirma sureleri gozonune alinmis ve sonuc olarak maksimum kritik burkulma yuku 48 saat yapay yaslandirma suresinde elde edilmistir. Ayrica, yaslandirma isil isleminin mikroyapi uzerindeki etkileri, SEM, EDS ve XRD kullanilarak tespit edilmistir.

Effects of aging heat treatment on machinability of alumina short fiber reinforced LM 13 aluminum alloy

In this paper, the surface integrity (Ra and Rmax) has been investigated with various aging heat treatment and machinability parameters in an aluminum-silicon based (LM–13) MMCs, produced by infiltration method. The composites have been subjected to heat treatment at different temperatures and times which was discussed in detail in an earlier publication (Altunpak and Akbulut, Teknoloji 8(4):331–339, 2005). In the milling of alumina short fiber reinforced LM–13 aluminum alloys, the surface integrity decreased when feed rate increased. It was found that increasing amount of fiber reinforcement and solutionizing temperature has a significant effect on the surface integrity and sub-surface damage of the materials. Increasing the solutionizing temperature and fiber reinforcement produced higher Ra and Rmax values. Microhardness measurement indicated that the sub-surface damage and the hardness increased by increasing the feed rate and fiber content.

The effect of aging heat treatment on the sliding wear behaviour of Cu–Al–Fe alloys

Aluminium bronze is one of the versatile wear resisting engineering materials that work under a corrosive environment with high stress. Alloys were produced by casting of C95200 and C95300 aluminium bronzes and aged. Wear behaviors, friction coefficient, and microstructure were investigated. The results indicated that a suitable aging treatment resulted in the formation of smaller alpha grains than their cast condition. These small alpha grains could improve the hardness and wear resistance of Cu–Al–Fe alloys. But with increasing aging temperature, the wear rate of the aged Cu–Al–Fe alloys initially decreased and then began to increase.

Mechanical Properties and Microstructure of Strip Casted Ag-27%Cu-25%Zn-3%Sn Brazing Alloy

This work sought to examine the suitability of twin roll strip casting for Ag-27%Cu- 25%Zn-3%Sn brazing alloy (BAg-7A) and to investigate the mechanical properties and microstructure of the strip. The effect of aging heat treatment on the properties was also studied. This new manufacturing process has applications in the production of the brazing alloy. XRD and microstructural analysis of the Ag-27%Cu-25%Zn-3%Sn strip represented eutectic microstructure of a Cu-rich phase and a Ag-rich matrix regardless of heat treatment. The results of mechanical tests showed tensile strength of 470MPa, a significant enhancement; and an 18% elongation of the twin roll casted strip, due mainly to the solid solution strengthening of Zn atoms (~20%) in the Cu-rich phases. Tensile results showed gradually decreasing strengths and increasing elongation with aging heat treatment. Microstructural evolution and fractography were also investigated and related to the mechanical properties.

Continuous Strip Casting, Microstructure and Performance of Ag-Cu Brazing Alloy

This study sought to examine the suitability of the continuous strip casting process as a new fabrication method for the Ag-Cu brazing alloy. Several continuous strip casting processes such as planar flow casting, melt dragging, and twin roll strip casting were applied to the manufacture of the Ag-32%Cu strip. In particular, twin roll strip casting was found to realize the best strip shaping ability and microstructural homogeneity. The effect of aging heat treatment on the microstructure and mechanical properties of a Ag-Cu strip was also investigated through tensile test, hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations, and electron probe microanalysis (EPMA). Tensile results showed gradually decreasing strengths and simultaneously increasing elongation with longer aging time. An appropriate TS strength of 283 MPa and a significantly enhanced plasticity of 41% were realized with aging condition of 670oC/2hrs. Finally, twin-rolled strips 1 mm thick could be cold-rolled to a very thin strip (80~100 μm thickness). The microstructural evolution and crystalline morphologies of Ag-Cu metastable strips were also investigated and related to the mechanical properties.

Surface Oxidation of Fe-48 mol%Al Single Crystal under a High Vacuum

In order to investigate the effect of aging heat treatment and surface orientation on oxidation during the nanopore formation of B2-type FeAl, the surface of Fe-48 mol%Al single crystal was analyzed by Auger Electron Spectroscopy (AES). Electropolished and plasma-cleaned surfaces were aged for 18 ks at 723 K, in vacuum (about 5 x 10 - 4 Pa). A thin oxide layer was already formed on the non-aged surface. A thicker oxide layer was grown on the aged surface, but the difference in thickness of the oxide layers was slight. Further, the orientation dependence of the thickness of the oxide layers was even smaller. The thickness of the oxide layer on the FeAl single crystal is comparable to that of the passive film on the aluminum foil. Therefore, it is concluded that the influence of the aging heat treatment on oxidation during the nanopore formation of B2-type FeAl is negligible.

Ｔｉ基ろうによるＴｉ−２１Ｖ−４Ａｌβ型チタン合金の液相拡散接合

Diffusion brazeability of β-type Ti alloy (Ti-21V-4Al) using newly developed Ti-20Zr-2OCu-2ONi amorphous filler has been investigatedd by electron microscopy, EDX microanalyses, and tensile tests of the joints. The brazeability was compared with solid state diffusion bondability of the same material, and the effect of aging heat treatments of the joint generally carried out for the alloy was also examined.Results of metallurgical examination of the joints indicated that the liquid layer at the joint interface became to disappear during holding at the joining temperature, and that the joint structure and composition finally became similar to those of the base metal.As for mechanical properties of the joint, even the joint made at 850C for 15 min under the joining pressure of 0.6 MPa, which is fairly lower than that required in solid state diffusion bonding of the same material, was fractured in the base metal with tensile strength of 680 MPa. Furthermore, the joint strength could be increased up to 1400MPa by aging heat treatment after joining.These results demonstrate that the use of developed Ti-base filler metal improves the diffusion weldability, and make it possible to produce the joint equivalent to the base metal even under a fairly low joining pressure.

Effect of aging heat treatment on the magnetic behavior of a gold-iron alloy

Susceptibility and magnetization measurements at temperatures below 200 K indicate the absence of long-range ferromagnetic spin order in ${\mathrm{Au}}_{82}$${\mathrm{Fe}}_{18}$, aged at 200\ifmmode^\circ\else\textdegree\fi{}C, in spite of a considerable increase of the internal susceptibility as a result of the aging treatment.

7075アルミニウム合金の腐食疲労き裂進展に及ぼす時効処理の影響

7075アルミニウム合金の腐食疲労き裂進展に及ぼす時効処理の影響