Temperature Heat Treatment Research Articles

The Effect of the Iso‐Thermal Heat Treatment on the Microstructure and Properties of Powder Bed Fusion–Laser Beam AlSi10Mg Alloy

The effect of iso‐thermal heat treatments on powder bed fusion–laser beam (PBF–LB) AlSi10Mg alloy has been studied; however, an extensive process–property relationship evaluation has not yet been undertaken. In addition, the coarsening of eutectic Si from low‐to‐high (200–500 °C) temperature heat treatment has not been investigated systematically. Therefore, AlSi10Mg alloy is heat‐treated at 200, 300, 400, and 500 °C for holding times ranging from 0.5 to 32 h. Uniaxial tensile and hardness tests are conducted, and the microstructure is characterized. A unique approach is adopted for estimating Si solubility where 200 °C heat‐treated microstructure data to estimate solute trapping due to the high cooling rate in the as‐fabricated state. It is observed that increasing the heat‐treatment temperature and time reduces the strength and strain‐hardening rate but increases the tensile elongation up to 400 °C heat treatment. At 500 °C, the yield strength increases, and the elongation reduces compared with the 400 °C heat treatment owing to the refined Fe containing dispersoid formation at 500 °C. The important outcome of this study is heat‐treatment process–property contour maps that are useful for fine‐tuning the mechanical properties of PBF–LB AlSi10Mg alloy for industrial prototyping application.

Effect of Heat Treatment under Different Atmospheres on the Bonding Properties and Mechanism of Ceramiziable Heat-Resistant Adhesive.

In this study, a heat-resistant adhesive was prepared using molybdenum-phenolic (Mo-PF) resin as the matrix and TiB2 particle as the ceramizable filler for bonding Al2O3 ceramic substrates. Firstly, Fourier transform infrared (FTIR) was used to characterize the chemical structure of the Mo-PF. Subsequently, thermo gravimetric analysis (TGA) and shear strength testing were employed to investigate the effects of heat treatment in different atmospheres on the thermal stability and residual bonding properties of the adhesive. To further explore the bonding mechanism of the adhesive after heat treatment in different atmospheres, scanning electron microscopy (SEM), compressive strength testing, and X-ray diffraction (XRD) were utilized to analyze the microstructure, mechanical strength, and composition evolution of the adhesive at different temperatures. The bonding strength of Al2O3 joints showed a trend of initially decreasing and then increasing after different temperature heat treatment in air, with the shear strength reaching a maximum value of 25.68 MPa after treatment at 1200 °C. And the bonding strength of Al2O3 joints decreased slowly with the increase of temperature in nitrogen. In air, the ceramicization reaction at a high temperature enabled the mechanical strength of the adhesive to rise despite the continuous pyrolysis of the resin. However, the TiB2 filler in nitrogen did not react, and the properties of the adhesive showed a decreasing tendency with the pyrolysis of the resin.

Investigation of the changes in gelation properties of hydroxypropyl distarch phosphate-surimi gel under different gelation-freezing treatments.

Frozen storage often leads to quality deterioration of surimi-based products. At present, most of the research focuses on improving the quality of surimi products by adding cryoprotectants, and there are few studies available on preparation technology. Therefore, the effects of different gelation-freezing treatments, high temperature heating-freezing treatment (HF), low temperature heating-high temperature heating-freezing treatment (LHF) and low temperature heating-freezing-high temperature heating treatment (LFH) on the quality changes of surimi gels containing hydroxypropyl distarch phosphate (HPDSP) during frozen storage were investigated. With the extension of frozen storage time, the quality of surimi gel in all groups decreased, but the quality of surimi gel with HPDSP was better than that of surimi gel without HPDSP. Compared with HF and LHF, the change range of breaking force, hardness, gumminess, whiteness and disulfide bond content of HPDSP-surimi gel treated with LFH was the least during the frozen storage. In the reheating process of LFH, HPDSP could absorb the water lost during freezing. Therefore, the change in the transverse relaxation time of HPDSP-surimi gels treated with LFH was smaller, with more immobile water and less free water and P22 of 96.81% and P23 of 0% at 16 weeks. In addition, the breaking deformation, cohesiveness, resilience, springiness and protein composition of surimi gels with and without HPDSP treated with HF, LHF and LFH did not change significantly during frozen storage. The combination of LFH and HPDSP could effectively reduce the quality change of surimi gel during frozen storage. © 2023 Society of Chemical Industry.

Effect of compaction pressure, sintering temperature and recovery heat treatment temperature of powder metallurgical Fe-20Mn-5Si-5Ni-8Cr shape memory alloy

Effect of compaction pressure, sintering temperature and recovery heat treatment temperature of powder metallurgical Fe-20Mn-5Si-5Ni-8Cr shape memory alloy

Short Duration Heat Treatments before Aging Increase Mechanical Hysteresis of Pseudoelastic NiTi Alloy

High temperature (550 °C) and short duration (10, 15, 20 s) heat treatments were performed on pseudoelastic NiTi alloy in addition to the conventional aging process in order to increase the mechanical hysteresis of the material. Pre-treated and aged samples were compared with plain aged ones through mechanical testing, powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The introduction of the pre-treatment, in combination with the aging process, was shown to increase the mechanical hysteresis of the aged samples up to ~30% after stabilization. XRD analysis showed how the introduction of the pre-treatment introduces a recovery of the residual stresses in the material microstructure, as well as the nucleation of different sets of metastable precipitates (such as TiNi3). We thus observe that the combination of pre-treatment and aging affects the alloys microstructure, causing a series of effects that synergise in increasing the material hysteresis.

C-CorA: A Cluster-Based Method for Correlation Analysis of RNA-Seq Data

Correlation analysis is a routine method of biological data analysis. In the process of RNA-Seq analysis, differentially expressed genes could be identified by calculating the correlation coefficients in the comparison of gene expression vs. phenotype or gene expression vs. gene expression. However, due to the complicated genetic backgrounds of perennial fruit, the correlation coefficients between phenotypes and genes are usually not high in fruit quality studies. In this study, a cluster-based correlation analysis method (C-CorA) is presented for fruit RNA-Seq analysis. C-CorA is composed of two main parts: the clustering analysis and the correlation analysis. The algorithm is described and then integrated into the MATLAB code and the C# WPF project. The C-CorA method was applied to RNA-Seq datasets of loquat (Eriobotrya japonica) fruit stored or ripened under different conditions. Low temperature conditioning or heat treatment of loquat fruit can alleviate the extent of lignification that occurs because of postharvest storage under low temperatures (0 °C). The C-CorA method generated correlation coefficients and identified many candidate genes correlated with lignification, including EjCAD3 and EjCAD4 and transcription factors such as MYB (UN00328). C-CorA is an effective new method for the correlation analysis of various types of data with different dimensions and can be applied to RNA-Seq data for candidate gene detection in fruit quality studies.

Influence of preheating temperature and post-weld heat treatment on microstructural and mechanical characteristics of the heat-affected zone in nodular cast irons with ferritic-pearlitic matrix

Influence of preheating temperature and post-weld heat treatment on microstructural and mechanical characteristics of the heat-affected zone in nodular cast irons with ferritic-pearlitic matrix

Effects of Heat Treatment on the Magnetic Properties of Nitinol Devices

The shape memory alloy Nitinol is considered safe for magnetic resonance imaging (MRI) after electropolishing. However, oxidized Nitinol has been implanted and utilized in non-implanted devices. The use of oxidized devices in MR fields motivates the need to understand the effects of heat treatment on magnetic susceptibility to develop standards. This work characterizes the impact of surface treatment and thermally-produced oxidation on the averaged magnetic susceptibility of Nitinol (including surface layers). It was found that thin oxide layers—not visible to the human eye—like those resulting from surface preparation techniques or low-to-moderate temperature heat treatment, can alter the averaged magnetic susceptibility of Nitinol devices by several percent. Importantly, higher temperature and longer duration heat treatments (900 °C for 300 min) can result in strong ferromagnetic characteristics, accompanied by an increase in magnetic susceptibility measurements of more than 100 fold. This result was attributed to a ferromagnetic nickel layer in a multi-layer surface oxide that formed during heat treatment. Heavy oxidation created a sufficiently large ferromagnetic Ni subsurface layer such that an ordinary neodymium magnet could levitate a Nitinol wire specimen. There are currently no standards to prevent companies from heavily oxidizing components, potentially creating MRI safety hazards.

Role of low substrate temperature deposition on Co–Fe thin films

This paper presents the role of the conventional and Soliton wave model deposition at low substrate temperature (300–100 K) on the structural, electric and magnetic properties of Co35Fe65 thin films deposited by thermal evaporation using bulk polycrystalline Co35Fe65 alloy. On account of obtaining superior quality magnetic thin films without any high temperature growth processes or heat treatment, the Soliton wave growth model at suitable low temperature range is used. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques are employed to investigate the various structural properties. Morphological and structural analyses of entire 30 nm Co35Fe65 thin films deposited on Si (100) substrate reveal that the stoichiometry is preserved over the whole temperature deposition and BCC crystalline formed with (110) texture. To attain the electrical and magnetic properties, resistivity and vibrating-sample magnetometer (VSM) measurements are evaluated. Soliton wave model deposition significantly increased magnetic anisotropy constant K1 = 0.105 Merg/cm3, MR/MS = 0.83 and coercivity HC = 272 Oe at 300 K when the compared to conventional deposition range in this work (K1 = 0.014 Merg/cm3, MR/MS = 0.6 and HC = 50 Oe). Growth with novel approach of Co35Fe65 thin films highlights the reasonable low coercivity, the high saturation magnetization, the high magnetic anisotropy and the low electrical resistivity values, with tailored grain size, make them feasible to use in magnetic sensor technology in the near future.

Effect of thermal treatment on microbiological, physicochemical and structural properties of high pressure homogenised hazelnut beverage

The aim of this study was to investigate the effect of low (65, 72 and 85 °C) and high (105, 110 and 115 °C) temperature heat treatment on the microbiological, physical and chemical properties of high pressure homogenised hazelnut beverage. The total number of aerobic bacteria decreased with heat treatment and was not detected after 72 °C and higher heat treatments. The pH value of hazelnut beverage did not change significantly as a function of temperature (P>0.05). The total soluble content and soluble protein values of the low or high heat treated hazelnut beverage were significantly decreased after the heat treatments considered non-thermal treated ones, and also serum separation was adversely affected (P<0.05). Changes in colour components showed an increase in browning of hazelnut beverage by thermal treatment. The viscosity values of the samples significantly increased depending on the temperature except for the 65 °C treatment (P<0.05), and Herschel Bulkley’s model was sufficient to describe the flow behaviour. Heat treatment at 85 °C for 5 min and higher temperatures led to an increase in particle size due to protein denaturation. Our results showed that the ideal temperature-time parameters were determined as 20 min at 72 °C and 1 min at 105 °C, based on microbiological results and better physicochemical properties.

Chemical Characterization of the Crystalline Phases in Agglomerated Fluxes and Slags for Shielded Metal Arc Welding (SMAW)

The aim of this work is to study the difference between the crystalline phases of used fluxes and obtained slags after Shielded Metal Arc Welding (SMAW). It is well known that The weld pool solidifies into the weld metal while the lighter molten flux floats on the top surface and solidifies as a slag layer that can be easily removed .The effects of individual flux ingredients as well as their interaction effects on weld metal composition have been investigated in this paper. The mass concentrations between fluxes (FA, FB and FC) and slags (SA, SB and SC) summarize the physico-chemical behavior of elements transfer between base metal, filler metal, flux and slag forming during welding of pipelines by SMAW process. The analysis of different fluxes phases and slags by X-ray diffraction allowed to detect the presence of different crystalline phases, which were formed at low temperature (T &lt;1000°C) heat treatments, and during fluxes confection. As for the slags, the presence of new crystalline phases which have been formed at high temperatures.

STUDY OF PARTIALLY STABILIZED CE DOPED ZRO2 CRYSTALS BY ELECTRON PARAMAGNETIC RESONANCE

The study of crystals of ZrO2 solid solutions (PSZ) stabilized with yttrium and cerium oxides was carried out by electron paramagnetic resonance (EPR) in the X and Q range. The presence of Zr3+ centers in annealed ZrO2 crystals stabilized only by yttrium oxide (2.8 mol.% Y2O3) is established. Another kind of paramagnetic O−centers appear when CeO2 is added to ZrO2 crystals in addition to yttrium oxide. To estimate the concentration of Ce3+ ions in PZS crystals, EPR spectra were recorded in the presence of a reference specimen at 7 K. Paramagnetic Ce3+ ions have been identified and their relative amounts in PSZ crystals before and after high−temperature heat treatment has been measured. The annealing in air leads to a decrease in the concentration of Ce3+ ions for all compositions and changes the color of the crystals from red to white. After annealing in the 2.0Y0.8Ce3Zr sample, the amount of paramagnetic Ce3+ ions decreased approximately twice. Paramagnetic centers from Ce3+ are not detected in a the sample with a low cerium content of 0.1 mol.% after annealing which indicates the complete transition of Ce3+ to the Ce4+ state. It is shown that the formed paramagnetic centers of cerium are bound by strong exchange interactions. No angular dependence of the EPR lines for the paramagnetic Ce3+ cations on the applied external magnetic field was observed. The probable reason for the absence of such angular dependence is that impurity rare−earth ions are located next to each other, forming impurity clusters with effective spin Seff = 1/2.

Mechanical performance of Cr-alloyed PM steel after different sintering and heat treatment operations

Main benefits of the PM technology versus conventional steel making processes in the manufacture of structural steel parts are high material utilization, low energy consumption and short production time. These benefits are fully exploited by choosing the right combination of material and processing route to get the required mechanical properties at a low production cost. Powder grades pre-alloyed with Cr are robust and cost effective materials which are suitable for high performance PM steel components. This paper presents mechanical properties of Cr-alloyed PM steel obtained after different processing routes, including high temperature sintering, sinter-hardening and heat treatment by low pressure carburizing. Static mechanical data are presented as well as results from plane bending fatigue tests. Microstructures are also shown and correlated with the mechanical properties obtained for the respective processing routes.

3D Hierarchical nano-flake/micro-flower iron fluoride with hydration water induced tunnels for secondary lithium battery cathodes

As a potential multi-electron electrode material for next generation lithium ion batteries, iron fluoride (FeF3) and its analogues are attracting much more attentions. Their microstructures are the key to achieve good electrochemical performances. In this work, FeF3·3H2O nano-flakes precursor with high crystallinity and flower-like morphology is synthesized successfully, by a liquid precipitation method using Fe(NO3)3·9H2O and NH4HF2 as raw materials. The formation and the crystal growth mechanisms of the FeF3·3H2O precursors are investigated and discussed. After different temperature heat-treatment and followed by ball-milling with Super P, the as-prepared FeF3.0·33H2O/C and FeF3/C nanocomposites are used as cathode materials for lithium ion batteries. The FeF3.0·33H2O/C nanocomposite exhibits a noticeable initial specific capacity of 187.1 mAh g−1 and reversible specific capacity of 172.3mAhg−1 at .1C within a potential range of 2.0–4.5V. The capacity retention is as high as 97.33% after 50 cycles. Combined with HRTEM test, it confirms that the hydration water is not harmful but useful, namely, the tunnel phase formed with the hydration water is crucial to unobstructed Li+ diffusion, and therefore leading to excellent electrochemical performances.

Mechanism of generation of large (Ti,Nb,V)(C,N)-type precipitates in H13 + Nb tool steel

The characteristics and generation mechanism of (Ti,Nb,V)(C,N) precipitates larger than 2 μm in Nb-containing H13 bar steel were studied. The results show that two types of (Ti,Nb,V)(C,N) phases exist—a Ti-V-rich one and an Nb-rich one—in the form of single or complex precipitates. The sizes of the single Ti-V-rich (Ti,Nb,V)(C,N) precipitates are mostly within 5 to 10 μm, whereas the sizes of the single Nb-rich precipitates are mostly 2–5 μm. The complex precipitates are larger and contain an inner Ti-V-rich layer and an outer Nb-rich layer. The compositional distribution of (Ti,Nb,V)(C,N) is concentrated. The average composition of the single Ti-V-rich phase is (Ti0.511V0.356Nb0.133)(C x N y ), whereas that for the single Nb-rich phase is (Ti0.061V0.263Nb0.676)(C x N y ). The calculation results based on the Scheil–Gulliver model in the Thermo-Calc software combining with the thermal stability experiments show that the large phases precipitate during the solidification process. With the development of solidification, the Ti-V-rich phase precipitates first and becomes homogeneous during the subsequent temperature reduction and heat treatment processes. The Nb-rich phase appears later.

Growth of 3C-SiC on Si(100) by LPCVD using a modified process after the clean step

A modified method is applied to grow a void-free 3C-SiC thin film of better crystal quality on the Si(100) substrate in a mixed gas of C3H8, SiH4 and H2 using low pressure chemical vapor deposition. The modified method adds a low temperature and low pressure heat treatment step after the clean step and subsequent a high flow carbon-based precursor gas-on step. The X-ray intensity of the 3C-SiC(200) peak is enhanced intensively using this modified method. The better crystal quality of 3C-SiC is confirmed by both X-ray diffraction and Raman spectra data. The modified method leads to a better crystal quality and surface morphology of the 3C-SiC film grown on Si(100) due to the better carbonized surface morphology. Moreover, the modified method can completely remove the void formation during the whole process. Morphological and structure analysis using scanning electron microscopy and transmission electron microscopy reveal no void defects at the 3C-SiC/Si(100) interface.

Effect of the FCAW Welding Process and Post Weld Heat Treatment on the Properties and Microstructure of the Weld Joints of Heat Treated 4330V Steel

4330V is a high strength, high toughness, heat treatable low alloy steel for application in the oil, gas and aerospace industries. It is typically used for large diameter drilling parts where high toughness and strength are required. The research describes the effect of preheat temperature, interpass temperature, heat input, and post weld heat treatment on strength, hardness, toughness, and changes to microstructure in the weld joint. Welding with the lower heat input and no post weld heat treatment resulted in optimal mechanical properties in the weld metal. Austempering at 400 °C resulted in optimal mechanical properties in the HAZ. Increasing preheat and interpass temperature from 340 °C to 420 °C did not improve Charpy V-notch values or ultimate tensile strength in the weld metal or heat affected zones. The higher temperature increased the width of the heat affected zone. Austempering at 400 °C reduced HAZ hardness to a level comparable to the base metal. Both tempering and austempering at 400 °C for 10 hours reduced toughness in the weld metal.

The Determination of Solution Temperature for NCu30-4-2-1 Alloy

NCu30-4-2-1 alloy was treated by the two methods of in situ observation experiment at high temperature and common heat treatment to determine solution temperature. High temperature metallurgical microscope was used to in situ observation of microstructure evolution of NCu30-4-2-1 alloy during heating process. The microstructures of the samples were observed by optical microscope. The results show that the as-cast microstructure of NCu30-4-2-1 alloy is composed by dendritic α-Ni-based solid solution and net-like (α+β) eutectics. The morphology of strengthening phase β-Ni3Si is graininess distributing on the grain boundary. The optimum solution temperature is both determined as 950°C by the two methods. The two methods of in situ observation experiment at high temperature and common heat treatment have comparability.

Investigating the Effects of Process Variables on the Residual Stresses of Weld and Laser Cladding

Weld cladding was investigated using a nickel alloy clad on a high strength low alloy carbon steel substrate. The effects of pre-heat temperature, clad material and post-weld heat-treatment are examined, along with the potential for thinner clad layers using laser cladding. Experimental residual stress measurements show good correlation with the simulation model. Metallurgical studies illustrate good fusion between clad and substrate materials. The potential for a fatigue-resistant cladding was demonstrated in a stainless steel clad with the possible use of post-cladding operations to enhance the outcomes for the nickel alloy clad.

Recrystallization, texture evolution, and magnetostriction behavior of rolled (Fe81Ga19)98B2 sheets during low-to-high temperature heat treatments

In order to study the texture evolution and magnetostriction behavior in the rolled Fe–Ga–B sheets during the heat treatments from low to high temperatures, (Fe81Ga19)98B2 sheets were prepared and investigated. The phase structure, recrystallization, grain size, texture evolution, and magnetostriction behavior during the annealing from 525 to 1200 °C for 1–5 h were investigated using X-ray diffraction, electron backscattering diffraction, and standard strain-gauge measurements. Results indicated that the primary recrystallization temperature for 1-h annealing was found as 525–575 °C in (Fe81Ga19)98B2 sheets. Annealing the sample below 575 °C for 1 h, the release of rolling stress and increase of 〈100〉 η-fiber texture during the primary recrystallization jointly resulted in a rapid improvement in magnetostriction. After annealed between 575 and 1100 °C for 1 h, the grains of the sheets underwent a normal growth, and the three (α-, γ- and η-fiber) types of textures kept an approximate balance, leading to a plateau of magnetostriction around 75 ppm. When the abnormal grain growth proceeded above 1100 °C for 1 h, the proportion of η-fiber texture markedly increased, and the magnetostriction was subsequently increased to 97 ppm. For longer annealing durations, the strong ideal cube texture (η-fiber) was firstly formed and then changed to undesired texture (γ-fiber), producing a corresponding magnetostriction peak of 136 ppm at 2 h for the annealing at 1200 °C. The clear correlation among heat treatments, recrystallization, texture, and magnetostriction provides an essential understanding for Fe–Ga–B alloy sheets.