Heat Treatment Behavior Research Articles

Influence of Cobalt Content on Heat Treatment Behavior and Abrasive Wear Characteristics of Multi-Component White Cast Iron

Influence of Cobalt Content on Heat Treatment Behavior and Abrasive Wear Characteristics of Multi-Component White Cast Iron

Preparation, Heat Treatment and Corrosion Behavior of Amorphous Ni-W/ZrO<sub>2</sub> Composite Coating

A Ni-W/ZrO2 composite coating was prepared by electrodeposition from a Ni-W bath containing zirconia solid particles suspended in an electrolyte solution by stirring. Results showed that the presence of zirconia particles influenced the electrodeposition, surface morphology, crystallographic structure, thermal treatment and corrosion resistance of the obtained composite coating. By comparison to Ni-W alloy electrodeposition both W content in the Ni-W matrix and deposition current efficiency for the composite coating decreased. After heat treatment at 400 °C for 1 h some embedded zirconia particles were removed from the Ni-W matrix and W was enriched at the top surface of the deposit. Scanning electron microscopy (SEM) results revealed that the composite coating had a granular morphology and was crack-free. A differential scanning calorimetry (DSC) experiment combined with X-ray diffractometry (XRD) indicated that the Ni-W/ZrO2 composite coating was amorphous. The microhardness of the composite coating was higher than that of the nanocrystalline Ni-W alloy. After heat treatment of the composite coating its microhardness and corrosion resistance in 3% NaCl solution were greatly enhanced.

Effects of electromagnetic field on structure and heat treatment behavior of Mg-Li-Al alloys

The effects of external fields such as electromagnetic field on the structure and heat treatment behavior of Mg-Li-Al alloys were studied. Mg-8Li-3Al alloys cast with and without electromagnetic stirring were used for solution treatment and aging treatment. Experimental results show that the dendritic arms are broken and a large quantity of equiaxed grains appear in the microstructure of specimens with electromagnetic stirring (EMS). With the increase of the quenching temperature(150–350 °C), the solution of Mg and Al in solid β phase increases, and the Brinell hardness of the alloy increases as well. Aging peak and over aging happen because θ (MgLi 2Al) which precipitates in the β matrix and strengthens the alloy is unstable and transforms to stable AlLi phase. Aging curves of EMS specimens change in a smaller amplitude.

Influence of Advances in Technologies for the Management of Aircraft Structural Integrity within RAAF

The basic concept of an Aircraft Stuctural Integrity Program is to ensure that airframes are adequately managed to ensure safe operation without catastrophic failure, to maximise fleet availibilty and to minimise cost of ownership. In managing these three aspects, a number of conventional and advanced technologies are being adopted and applied within the RAAF. Composites and bonding technology has been developed and transitioned onto various RAAF aircraft over many years in the form of Bonded Patch Repairs to airframe structures (wing and fuselage). Based upon conventional heat treatment behaviour of aluminium alloys, Retrogressive Re-Ageing technology is being transitioned to minimise stress corrosion cracking. From structural mechanics and FEA technologies, Geometric Shape Optimisation methods have been applied to minimise peak stress thresholds within aged airframe structures. To manage structural degredation (fatigue and corrosion) a number sensor-based monitors are being developed and applied on RAAF aircraft. Finally, using the reliability methodology, a proactive management program to assess the extent of corrosion degradation within a whole aircraft is being instituted. This methodology is being articulated through a new paradigm known as “Environmental Degradation Management System – Tool Box” (EDMS-TB). Within RAAF it can be demonstrated that candidate technologies which are adopted have direct and in-direct positive influences within ASIPs to address the key structural integrity parameters of Safety, Availability and Cost of Ownership.

Ｔｉ‐Ｃｒ系合金の相構成と等温時効挙動

By virtue of their high strength and excellent cold workability, β titanium alloys have been used for various applications, e.g. parts of airplanes and eyeglass frames. Generally, β titanium alloys contain vanadium and molybdenum as alloying elements. However, the official quotations of vanadium and molybdenum are unstable. Therefore, use of those alloying elements is limited. We adopted chromium and iron, whose official quotations are more stable than those of vanadium and molybdenum, and reported some parts of the research of Ti-13Cr-1Fe-3Al alloy. Cr is one of the attractive elements to develop the cost affordable titanium alloys. Thus, it is very important to investigate the Ti-Cr binary alloys as basic study. It is also important to study the heat treatment behavior of the Ti-Cr alloys. In this study, phase constitution and isothermal aging behavior of Ti-Cr alloys was investigated by measurements of electrical resistivity and Vickers hardness, X-ray diffraction, optical and scanning electron microscope observations and tensile tests. The obtained results are as follows. In solution treated and quenched stated (STQed) state, hcp martensite, α’ was only identified at 3Cr alloy. β phase and α’ were identified at 5Cr alloys. Above 5Cr, β phase was identified. In 7Cr and 10Cr, athermal ω was also identified. Maximum of HV appeared at 7Cr and then HV decreased with increase of Cr content up to 15Cr. Above 15Cr, HV slightly increased due to solution hardening by Cr addition. On isothermal aging, precipitation of the α phase was delayed by Cr addition. In STQed state, tensile strength is 961 MPa in 10Cr, 988 MPa in 13Cr and 967 MPa in 15Cr, respectively. Elongation is 27.1 % in 10Cr, 26.8 % in 13Cr and 23.9 % in 15Cr, respectively. In 15Cr alloy, nominal stress-nominal strain curve showed work-softening phenomenon after yield stress, whereas S-S curve of 10Cr alloy did not show that phenomenon. In 773 K-12 ks aged state, tensile test specimens of 10Cr and 13Cr were broken with no elongation, while the specimen of 15Cr alloy was broken after about 5 % in elongation. It is considered that difference of tensile properties between the 15Cr and others is due to differences of shape and volume fraction of precipitated α.

Relationship between heat treatment and corrosion behaviour of Mg-3.0%Nd-0.4%Zr magnesium alloy

The corrosion behaviour of Mg-3.0Nd-0.4Zr (NK30) magnesium alloy was investigated in as-cast (F), solution treated (T4) and peak-aged (T6) conditions in 5% NaCl solution by immersion tests and electrochemical measurements. The results of immersion test show that NK30 alloy exhibits better corrosion resistance in F condition than it does in the other two conditions due to the more compact corrosion film formed on alloy in F condition. The potentiodynamic polarization curves show that the overpotential of cathodic hydrogen evolution reaction on NK30-F is much higher than that on NK30-T4 and NK30-T6. The corrosion potentials of NK30 increase in the following order: F<T4<T6. The results of electrochemical impedance spectroscopy (EIS) also confirm that the corrosion film of NK30-F plays a more protective role than that of NK30-T4 and NK30-T6.

Generation of voids in the alkyl layers of an alkyl derivative of boehmite by heat treatment and adsorption behavior of the voids

The solvothermal reaction of aluminum isopropoxide in 1-decanol yielded the decyl derivative of boehmite [AlO(OH) (1− X )(OC 10H 21) X ]. This product belongs to a class of intercalation compounds where the guest moieties are covalently bonded to the host inorganic (boehmite) layers. In this work, the alkyl chains in the boehmite layers were partially removed by heat treatment in an He flow. X-ray diffraction (XRD), thermogravimeter (TG), and N 2 adsorption measurement showed that the voids surrounded by the alkyl chains were generated by the heat treatment. When the decyl derivative of boehmite was heated at 310 °C for 3 h in the He flow, the voids had the largest volume, but prolonged heat treatment resulted in partial collapse of the boehmite layers causing a smaller void volume.

Phase Constitution and Heat Treatment Behavior of Zr-Nb Alloys

Phase constitution in the solution-treated and quenched state and the heat treatment behavior were investigated by electrical resistivity, hardness, and elastic modulus measurements, X-ray diffraction, and optical microscopy. Hexagonal martensite and the β phase were identified in the Zr-5mass%Nb alloy. β and ω phases were identified in the Zr-10 and 15mass%Nb alloys, and only the β phase was identified in the Ti-20Nb alloy. Resistivity at RT, Vickers hardness and elastic modulus increased up to 10Nb and then decreased dramatically at 15Nb. Above 15Nb, these values slightly decreased. The elastic moduli for 15Nb and 20Nb were 59.5 and 55.5 GPa, respectively. On isochronal heat treatment, the isothermal ω phase precipitated between 473 and 623 K and then the α phase precipitated in the 10Nb, 15Nb and 20Nb alloys.

The Effect of Oxygen on Heat Treatment Behavior of Titanium-50mass%Tantalum-5mass%Zirconium Alloy

To develop new shape memory and super-elastic alloys for medical applications, titanium alloys using non-toxic metallic elements, such as Ta and Nb, are being actively investigated. In this study, aimed at developing new shape memory Ti alloys, we investigate the effect of oxygen, a powerful alpha stabilizing interstitial element, on the heat treatment behavior of Ti-50mass%Ta-5mass%Zr through electrical resistivity and Vickers hardness measurements and shape-recovery tests. Ti-50Ta-5Zr-0.14Ox and 0.33Ox alloys, and the β and α” bi-phase was confirmed by XRD. Only the β phase was identified in the Ti-50Ta-5Zr-0.62Ox alloy. Upon isochronal heat treatment, the resistivity at LN and resistivity ratio of Zr-0.33 and 0.62Ox alloys decreased up to around 523 K. In the 5Zr-0.62Ox alloy, orthorhombic martensite and the α” and β phases were identified in the specimens heat-treated at 473 and 523 K. The decreases in resistivity at liquid nitrogen temperature and resistivity ratio are due to the formation of α” during isochronal heat treatment. The formation of α” was confirmed by X-ray diffraction in the 5Zr-0.62Ox alloy. The shape memory effect was observed in 5Zr-0.14 and 0.33Ox alloys and the shape recovery ratio of both alloys was about 40% at 673 K.

Ag-25mass%Pd-Cu合金の熱処理挙動に及ぼすCu添加量の影響

Ag-25mass%Pd-Cu合金の熱処理挙動に及ぼすCu添加量の影響

Computational modelling of heat and mass transfer during the high-temperature heat treatment of wood

During the heat treatment process, the heat and mass transfer takes place between the solid and the drying medium, and the moisture evaporation occurs within the solid due to the capillarity action and diffusion. In the current work, the three-dimensional Navier–Stokes equations along with the energy and concentration equations for the fluid coupled with the energy and mass conservation equations for the solid (wood) are solved to study the conjugate heat treatment behaviour. Whitaker’s continuum approach has been used to obtain the equations for the liquid and vapour migration within the solid. Three moisture phases are accounted for: free water, bound water, and water vapour. The model equations are solved numerically by the commercial package FEMLAB for the temperature and moisture content histories under different treatment conditions. The model validation is carried out via a comparison between the predicted values with those obtained experimentally. The comparison of the numerical and experimental results shows good agreement, implying that the proposed numerical algorithm can be used as a useful tool in designing high-temperature wood treatment processes.

Heat Treatment Behavior of Tungsten Heavy Alloy

This paper focuses on the variations of static and dynamic properties of tungsten heavy alloy with heat treatment. The matrix phase of 93W-4.9Ni-2.1Fe (weight percent) has been penetrated into W/W grain boundaries during a cyclic heat treatment which consists of repeated isothermal holdings at 1150 °C and water quenching between them. By applying the cyclic heat treatment, the impact energy of tungsten heavy alloy is increased about three times from 57 to 170 J. When the tungsten heavy alloy is cyclically heat treated at 1150 °C and then re-sintered at 1485 °C, W/matrix interface is changed from round to undulated shape. The irregularity of the interface is increased with increasing the number of heat treatment cycles. From the measurement of the residual stress of W grains by X-ray diffraction, it is found that the irregularity of the interface is closely related with strain energy stemmed from the difference of thermal expansion coefficient between W particles and matrix phase. From dynamic ballistic test, it is found that the tungsten heavy alloy with undulated W grains forms many narrow fracture bands which are preferential for the self sharpening effect, thus, for the improvement of the penetration performance.

Numerical simulation of the forging process

The principal objective of this paper is to provide a short overview of recent research in the numerical simulation of forging, with an emphasis on applications rather than the mathematical formulations which are well documented elsewhere. The paper addresses a number of specific topics, including Process Modelling, Tool and Die Design, Interface Phenomena, Material Phenomena and Computational Aspects. The paper also looks at recent developments in re-meshing and its importance in realistic forging modelling. While many features of the forging process have been covered there are still a number, such as inter-stage heat treatment and post-process thermal behaviour, that have received little attention. A holistic approach to forging modelling is still awaited in which all features of the process together with the influence of aspects such as press behaviour are considered.

Ti-13Cr-1.2Fe-Al合金の等時熱処理挙動に及ぼすAl添加量の影響

In this study, the effect of Al content on isochronal heat treatment behavior in Ti-13Cr-1.2Fe-Al alloys was investigated by measurements of electrical resistivity and Vickers hardness, X-ray diffraction and transmission electron microscope observation. The results obtained are as follows. In the solution treated and quenched state (STQ), resistivity (ρ) at liquid nitrogen (LN) and room temperatures (RT) increased monotonously with Al content. 0%Al and 3.0%Al alloys consisted of retained β phase and athermal ω. In the isochronal heat treatment, two minima of resistivity were observed at 623 K and 823 K. The former is due to the precipitation of isothermal ω phase and the latter is α precipitation. The temperature of resistivity minimum attributing to ω phase precipitation gradually increases with increasing of Al content. In 4.5%Al and more, the minimum of resistivity by ω precipitation disappears and the minimum caused by α precipitation remained. It is considered that Al content above 4.5% was suppressed ω precipitation and enhanced α precipitation.

Effect of Alloying Elements on Heat Treatment Behavior of Hypoeutectic High Chromium Cast Iron

The relationship between hardness and volume fraction of retained austenite (Vy) was investigated in heat-treated 16mass% and 26 mass%Cr hypoeutectic cast irons with and without addition of a third alloying element of Ni, Cu, Mo and V. In as-hardened state, hardness changed remarkably depending on the Vy. Overall, Ni and Cu decreased hardness but Mo increased it. Hardness increased in 16 mass%Cr cast iron but decreased in 26 mass%Cr cast iron by V addition. The Vy increased with Ni, Cu and Mo addition but diminished with V addition in 16 mass%Cr cast iron. In 26 mass%Cr cast iron, Ni and Mo increased the Vy but Cu and V reduced it. Higher austenitization caused more Vy. Curves of tempered hardness showed an evident secondary hardening due to precipitation of special carbides and transformation of destabilized austenite into martensite. High tempered hardness was obtained in the specimens with high Vy in as-hardened state. Maximum tempered hardness (H Tmax ) was obtained when Vy was less than 20% and it increased with an increase in Mo content. The H Tmax slightly increased with V content in 16 mass%Cr cast iron and decreased in 26 mass%Cr cast iron. Ni and Cu did not show significant effects on H Tmax . The highest value of H Tmax was obtained in both series of cast irons containing Mo.

The effect of aluminum content on phase constitution and heat treatment behavior of Ti–Cr–Al alloys for healthcare application

As life expectancy steadily increases, developing reliable functional materials for healthcare applications gains importance. Titanium and its alloys, while attractive for such applications, are expensive. The present investigation suggests that it may be possible to reduce costs by using new, low-cost beta Ti alloys. To assess their reliability, the heat treatment behavior of beta Ti alloys, Ti–7 mass% Cr with varying Al content (0%, 1.5%, 3.0% and 4.5%), was investigated through electrical resistivity and Vickers hardness measurements. In the Ti–7Cr–0Al alloy quenched from 1173 K, only the beta phase was identified by X-ray diffraction (XRD). In Ti–7Cr–1.5 to 4.5 Al alloys, XRD detected both beta and orthorhombic martensite. On isochronal heat treatment behavior of Ti–7Cr–3.0, 4.5 Al alloys, resistivity at liquid nitrogen temperature and resistivity ratio increased between 423 and 523 K.These increases are due to reverse transformation of orthorhombic martensite to the metastable beta phase.

Effect of Zr Addition on Phase Constitution and Heat Treatment Behavior of Ti-25mass%Nb Alloys

In an attempt to optimize the shape recovery temperature, the effect of Zr addition on phase constitution and heat treatment behavior is investigated by electrical resistivity and Vickers hardness (HV) measurements, X-ray diffractometry (XRD) and shape recovery tests. Ti-25mass%Nb-0, 2, 7 and 12mass%Zr alloys (abbreviated as 0Zr, 2Zr, 7Zr and 12Zr, respectively) were prepared using an arc-furnace. Specimens were solution-treated at 1273 K for 3.6 ks and then quenched by iced water (STQ). STQed specimens were isochronally heat-treated. In 0Zr and 2Zr, only the orthorhombic martensite phase a” was identified by XRD, while the two-phase alloys a” and b were identified in 7Zr and 12Zr. In 7Zr, resistivity at liquid nitrogen and room temperature (rLN and rRT, respectively) and resistivity ratio (rLN/rRT) drastically increased at 523 K because of the reverse-transformation of a” into b phase. Thereafter, resistivity and resistivity ratio decreased with increasing heat treatment temperature due to isothermal w precipitation. Starting temperature of shape recovery is 623 K in 7Zr and 523 K in 12Zr. In 7Zr, shape recovery ratio is about 80% at 723 K, which is the maximum obtained in this study.

Effect of Tin Addition on Phase Constitution and Heat Treatment Behavior in Ti-40Ta-Sn Alloys

Using Ti-40mass%Ta-0, -4, -8 and -12mass%Sn alloys, the effect of Sn addition on phase constitution in the solution treated and quenched state and isochronal heat treatment behavior is studied by electrical resistivity and Vickers hardness measurements and X-ray diffactometry. To confirm shape memory effect of some of these alloys, shape-recovery test was also performed. Orthorhombic martensite, ” was identified in Ti-40Sn-0 to 8Sn alloy quenched from 1173K, while phase was identified in STQed Ti-40Ta-12Sn alloy. On isochronal heat treatment, increases of resistivity at LN and resistivity ratio were observed in only 8Sn alloy, because these increases are due to reverse-transformation of ” to phase. From result of shape recovery test, shape memory effect was observed in Ti-40Ta-4 and 8Sn alloys

Experimental Investigations and Computer Simulation of the Liquid Fraction Evolution during the Solidification of Alloys Suitable for Semi-Solid Processing

One important parameter for the processing of materials by semi-solid forming is the actual distribution of the solid and liquid phases in the semi-solid range. This parameter defines the process stability for the forming step. Therefore it is necessary to obtain information about the materials behaviour in the semi-solid state for different materials grades. This kind of information can be obtained by experimental studies in the interesting temperature range or by calculations with simulation programs using thermodynamic data validated by experiments. This work shows the results of experimental studies and thermodynamic calculations of the solidification and heat treatment behaviour of the aluminium alloy A319 and the steel X210CrW12. The experimental studies of solidification and heat treatment of these alloys were carried out using a differential thermal analysis system (DTA). The theoretical fraction of liquid content was calculated from the DTA signal by using a software module called Corrdsc. The experimental data obtained were used to validate the thermodynamic simulations of the solidification of semi-solid alloys. The simulations of the solidification process were carried out for equilibrium conditions, with the Scheil-Gulliver model as well as with diffusion calculations. The equilibrium and Scheil-Gulliver calculations were performed by the program Thermo-Calc, and the diffusion by the program DICTRA. The required thermodynamic and mobility data for multicomponent systems were taken from the data bases COST 507 light alloys, TCFE2000 Steel/Alloys and MOB2 mobility and from newly added data. The comparison of calculated phase transformations and fractions of liquid content with experimental data revealed a good agreement.

&amp;beta;単相領域温度から焼入れたTi-50Ta-Zr合金の相構成と熱処理挙動に及ぼすZr添加量の影響

&amp;beta;単相領域温度から焼入れたTi-50Ta-Zr合金の相構成と熱処理挙動に及ぼすZr添加量の影響