Effect Of Peak Temperature Research Articles

Study on Microstructure and Low‐Temperature Impact Toughness in Coarse Grain Heat‐Affected Zone of EH460 Steel

Herein, the effects of peak temperature on the microstructure and low‐temperature impact toughness of coarse grain heat‐affected zone (CGHAZ) of EH460 steel are investigated by Gleeble simulation welding. The low‐temperature impact toughness of CGHAZ decreases with the increase of peak temperature. With the increase of peak temperature, the microstructure of CGHAZ gradually changes from bainite to a mixed structure composed of bainite, intragranular ferrite, side lath ferrite, and a small amount of grain boundary ferrite. The inclusions size decreases as the peak temperature increases. The existence of large‐sized inclusions is conducive to the initiation and propagation of cracks, reducing the low‐temperature impact toughness of the material.

Effect of peak temperature on microstructure and mechanical performances of ART-Flash processed medium Mn steel

The combination of ART and Flash annealing has been utilized to enhance the mechanical properties of medium Mn AHSS, demonstrating significant effectiveness. However, the industrial application was constrained by the absence of research on the impact of critical processing variables. In this work, the peak temperature of the flash heating was varied in the intercritical field to manipulate the microstructure and mechanical response of a 5 wt% Mn steel. The mechanisms of microstructural evolution during heat treatment and deformation were thoroughly discussed through interrupted tensile testing. A collection of ultrafine multiphase structures, consisting of retained austenite (RA), ferrite, and martensite with flexible phase constituents, were constructed, resulting in an ultrahigh YS increment (∼450 MPa) and exceptional strength-ductility combination (YS: 1125 MPa, UTS: 1544 MPa, TE: ∼21 %). The significant strengthening is primarily attributed to the increase in α′-martensite, while the sustained TRIP effect induced by stable retained austenite is responsible for the appropriate ductility. The interaction between austenite and adjacent phases and grain size exhibit a crucial influence on the mechanical stability of austenite. Benefiting from the “shielding” effect provided by the surrounding martensite, the Flash-810 sample achieved great ductility, despite possessing only a 5 % volume fraction of retained austenite. The YS of the experimental steels is sensitive to peak temperature, while the UTS and ductility remains relatively stable. Our work suggests the substantial potential of intercritical flash heating in enhancing the mechanical response of medium Mn steels and the profound significance of controlling the peak temperature.

Effect of peak temperature on nanoscale Cu-rich re-precipitation behavior and strength-toughness of welding heat affected zones for Cu-bearing high strength steel

Effect of peak temperature on nanoscale Cu-rich re-precipitation behavior and strength-toughness of welding heat affected zones for Cu-bearing high strength steel

Modeling of welding residual stress in a dissimilar metal butt-welded joint between P92 ferritic steel and SUS304 austenitic stainless steel

In this study, a butt-welded joint between P92 ferritic steel and SUS304 austenitic stainless steel was fabricated with a nickel-based filler material. Based on Sysweld software, three-dimensional thermal-metallurgical-mechanical coupled finite element analyses were performed to investigate the hardness and welding residual stress in the welded joint. In the material behavior model, various factors influencing the formation and distribution of hardness and welding residual stress were carefully considered, including the austenitic transformation, martensitic transformation, and the tempering of martensite in P92 steel; the isotropic strain hardening, annealing effect, and melting effect of all materials; and the differential thermal expansion between dissimilar metals. The neutron diffraction method and hole-drilling strain gauge method were applied to measure the profiles of residual stress of the welded joint, respectively. Hardness mapping was performed on a weld cross-section specimen. The predicted results of welding residual stress and hardness are in good agreement with the measurements, respectively. The peak residual stresses in longitudinal and transverse directions are above 600 MPa in P92 steel. There are high tensile residual stress and significant cold work near the weld root in SUS304 stainless steel. The solid-state phase transformation induces compressive longitudinal residual stress in the heat-affected zone, high tensile transverse residual stress near the weld toe in P92 steel, and a significant stress gradient. The tempering effect can reduce the hardness and tensile residual stress in the heat-affected zone of P92 steel. The formation mechanism of welding-induced residual stress was illustrated based on the Satoh test. The effects of peak temperature, internal restraint, and differential thermal expansion are found to be decisive for the formation of residual stress. Large tensile residual stress can be generated with internal restraints, which promote the stress increase and lead to material yielding. A restraint factor was proposed for the quantitative assessment of stress evolution.

Effect of Peak Temperatures on Microstructure and Properties of Welding Coarse Grain Heat-Affected Zone of SA508 Gr.4N Steel

The effect of peak temperatures on the grain growth, microstructure transformation and Vickers hardness of the weld coarse grain heat-affected zone (CGHAZ) of SA508 Gr.4N steel for nuclear reactor pressure vessel was studied. The results show that different t8/5 time has no obvious effect on grain growth at the same peak temperature, but different peak temperatures have a great influence. The higher the peak temperature, the more obvious the effect on grain growth. The grain size distribution at different peak temperatures and t8/5 time conforms to the Gaussian normal distribution curve, and a grain growth model suitable for CGHAZ of SA508 Gr.4N steel has been established. The room temperature martensite structure can be obtained by treatment at different peak temperatures and t8/5 time. At the same peak temperature, there is no significant difference in martensite structure at different t8/5 time, and the size of martensite lath only increases with the increasing peak temperatures. At different peak temperatures and t8/5 time, grain size has less effect on the Vickers hardness, which is closely related to the room temperature microstructure of the material.

Energy-saving COVID–19 biomedical plastic waste treatment using the thermal - Catalytic pyrolysis

The rate of Biomedical waste generation increases exponentially during infectious diseases, such as the SARS-CoV-2 virus, which burst in December 2019 and spread worldwide in a very short time, causing over 6 M casualties worldwide till May 2022. As per the WHO guidelines, the facemask has been used by every person to prevent the infection of the SARS-CoV-2 virus and discarded as biomedical waste. In the present work, a 3-ply facemask was chosen to be treated using the solvent, which was extracted from the different types of waste plastics through the thermal–catalytic pyrolysis process using a novel catalyst. The facemask was dispersed in the solvent in a heating process, followed by dissolution and precipitation of the facemask in the solvent and by filtration of the solid facemask residue out of the solvent. The effect of peak temperature, heating rate, and type of solvent is observed experimentally, and it found that the facemask was dissolved completely with a clear supernate in the solvent extracted from the (polypropylene + poly-ethylene) plastic also saved energy, while the solvent from ABS plastic was not capable to dissolute the facemask. The potential of the presented approach on the global level is also examined.

The Growth Behavior for Intermetallic Compounds at the Interface of Aluminum-Steel Weld Joint.

In this work, the microstructure and growth behavior of Al-Fe intermetallic compounds (IMCs), which formed at interface of weld steel-aluminum joint, are successfully analyzed via the combination of experiment and physical model. A layer IMCs consists of Fe2Al5 and Fe4Al13, in which the Fe2Al5 is the main compound in the layer. The IMCs layer thickness increases with the increase of the heat input and the maximum thickness of IMCs layer is 22 ± 2 μm. The high vacancy concentration of Fe2Al5 IMCs provides the diffusion path for Al atoms to migrate through the IMCs layer for growing towards to steel substrate. By using the calculated temperature profiles as inputs, the combined 2D cellular automata (CA)-Monte Carlo (MC) model is applied to simulate the grain distribution and interfacial morphology evolution at the Al-steel interface. This 2D model simulates the IMCs nucleation, growth, and solute redistribution. The numerical results are in good agreement with the experimental results, suggesting that the growth process can be divided four stages, and the thickness of the Fe2Al5 layer increases nonlinearly with the increase of the growth time. The whole nucleation and growth process experienced 1.7~2 s, and the fastest growth rate is 8 μm/s. The addition of Si element will influence diffusion path of Al atom to form different interface morphology. The effects of peak temperature, cooling time, and the thermal gradient on the IMCs thickness are discussed. It shows that the peak temperature has the major influence on the IMCs thickness.

Effect of Welding Peak Temperature on Microstructure and Impact Toughness of Heat-Affected Zone of Q690 High Strength Bridge Steel.

The effect of peak temperature (TP) on the microstructure and impact toughness of the welding heat-affected zone (HAZ) of Q690 high-strength bridge steel was studied using a Gleeble-3500 thermal simulation testing machine. The results show that the microstructure of the inter critical heat-affected zone (ICHAZ) was ferrite and bainite. The microstructure of fine grain heat-affected zone (FGHAZ) and coarse grain heat-affected zone (CGHAZ) was lath bainite (LB), lath martensite (LM), and granular bainite (GB), but the microstructure of FGHAZ was finer. With the increase in peak temperature, the content of LB and GB decreased, the content of LM increased, and the lath bundles of LM and LB gradually became coarser. With the increase in peak temperature, the grain size of the original austenite increased significantly, and the impact toughness decreased significantly. When the peak temperature was 800 °C, the toughness was the best. For CGHAZ, the peak temperature should be less than 1200 °C to avoid excessive growth of grain and reduction of mechanical property.

Effect of Peak Temperature on Microstructure and Mechanical Properties of Thermally Simulated Welding Heat-Affected Zones for 09MnNiDR Steel

The microstructures and mechanical properties of various heat-affected zones (HAZs) for 09MnNiDR pressure vessel steel are systematically analyzed. The results show that at − 70 °C, the thermally simulated subcritical heat-affected zone (SCHAZ) reaches the impact toughness of 270 J, which is the highest among various HAZs. Owing to the appearance of martensite–austenite (M–A) constituents distributed along the grain boundary in the thermally simulated critical heat-affected zone and fine-grained heat-affected zone, the impact toughness sharply decreases compared with that of the SCHAZ. The impact toughness of the coarse-grained heat-affected zone (CGHAZ) reaches 20 J, which makes the CGHAZ the weakest zone. The microstructure of the CGHAZ is composed of relatively coarse bainite and ferrite. Moreover, the proportion of high-angle grain boundaries (HAGBs) in CGHAZ is the lowest, at only 22%. Coarse grain size, microstructural transformation, and different proportions of HAGBs significantly affect the impact toughness in each zone of HAZs.

Effect of Peak Temperature on SAC Nano-Reinforced Fillet Height

Recently, the addition of new materials into the conventional solder pastes provides a viable solution to optimize the material characteristics and properties of the nano-particle filled solder paste. Addition of titanium oxide (TiO2) nanoparticles shown that it can enable better performance of the solder. However, actual industry experiment in terms of its optimum thermal profile for improved strength through good spread of nano-particles in the solder is very costly and lengthy to set up. Hence, this paper presents a preliminary study of the interaction between two models of numerical simulation namely volume of fluid (VOF) and discrete phase model (DPM) then compare with previous experimental data. This paper aims to analyse the effect of peak temperature towards the fillet height of ultra-fine Sn-Ag-Cu (SAC) solder joints doped with TiO2 nanoparticles in an electronic assembly. For the purpose of this research, the weight percentage of the nanoparticles TiO2 with the SAC305 lead-free reinforced solder is varied at different peak temperature and investigated in terms of particles distribution, fillet height and thermal strain. This paper presents a 3D numerical simulation of nano-reinforced lead (Pb)-free solder at the ultra-fine joint component for 01005 capacitor with dimension of 0.2 x 0.2 x 0.4 mm³. The results obtained are confirmed by conducting an experiment using a field emission scanning electron microscope (SEM) joined with an EDS and X-ray diffraction machine. This study concludes that the best fillet height would be obtained at 250°C. The distributions of nanoparticles with 0.01 wt%, 0.05 wt%, and 0.15 wt% of weighted percentage are effectively observed by using the HRTEM analysis. Based on the study, higher temperature of the wetting region that range between 240°C and 255°C results in better particle distributions, and fillet height of the solder by using temperature in that range meets the requirement of IPC standards.

Effect of temperature and substrate surface roughness on wetting behavior and interfacial structure between Sn–35Bi–1Ag solder and Cu substrate

The effects of peak temperature (483 K and 533 K) and substrate surface roughness on wetting characteristics and interfacial structure between Sn–35Bi–1Ag solder and Cu substrates were studied. Results revealed that the wettability of Sn–35Bi–1Ag solder was enhanced with increasing surface roughness of Cu substrates and temperature. However, the surface topography characteristics (i.e., anisotropic or isotropic) had little effect on wettability of Sn–35Bi–1Ag solder. The liquid solder had a preferential spreading direction, which caused an elliptical triple-line pattern when Sn–35Bi–1Ag solder spread over an anisotropic surface, while the solder spread as almost a perfect circle when the surface of Cu substrate was isotropic. Besides, the surface roughness had little effect on the interfacial structure, while the interfacial IMCs increased with increasing the temperature. Moreover, the spreading process of Sn–35Bi–1Ag solder spreading on Cu substrates with different surface roughness was similar at 483 K and 553 K. The whole spreading process was featured with four distinguishable stages: (i) initial stage, (ii) rapid spreading stage, (iii) limited spreading stage and (iv) steady stage. Wetting kinetics of the rapid spreading stage and limited spreading stage were described by the Rn ~ t model and the values of n of the rapid spreading stage and limited spreading stage decreased with increasing surface roughness of Cu substrates, which indicated increasing surface roughness of Cu substrates increased slightly the spreading rate. However, the temperature and surface topography characteristics had little effect on the spreading rate. Meanwhile, the dynamic contact angle and time t could be characterized by an equation, i.e., cosθF – cosθ = (cosθF – cosθ0) e−kt. The value of k decreased with increasing surface roughness of Cu substrates, while the surface topography characteristics and the temperature had little effect on the value of k.

Microstructure and mechanical properties of thermal simulation CGHAZ of DP780 high strength steel

In order to reduce the weight of the vehicle, DP780 high-strength steel is a favorite choice of material in the automobile industry, because of its high strength. However, its coarse-grained heat affected zone (CGHAZ) acts as a deterrent for wider applications, making it necessary to find suitable welding parameters to ensure the reliability of the CGHAZ during operation. The present work focuses on the effects of peak temperature and heating rate on the microstructure and the mechanical properties of DP780 CGHAZ, during thermal simulation of welding. The results show that the microstructure of the CGHAZ is mainly composed of martensite (M), tempered martensite (TM), upper bainite (UB), primary austenite grain boundary (AGB) and ferrite (F). In terms of mechanical properties, the results of the welding simulation showed that, the toughness of the CGHAZ is significantly decreased, the elongation and impact energy are notably degraded; while, at the same time, the Rockwell hardness is improved. It is proven that reducing the heat input to the weld, using a lower peak temperature (1130 °C) and heating rate (65 °C min−1) for welding, has a positive influence on improving the performance of the CGHAZ.

Effect of Pyrolysis Temperature and Time on Properties of Palm Kernel Shell-Based Biochar

Pyrolysis is a thermal decomposition of biomass occurring in the absence of oxygen. Biochar (solid), bio-oil (liquid) and biogas (gas) are the typical products from pyrolysis of biomass. This endothermic process produced biochar with high carbon content. During pyrolysis, the material is heated up from ambient to a peak temperature and remains for a defined residence time. Therefore, the pyrolysis peak temperature and the residence time are the key parameters for pyrolysis. Studies on the effect of these parameters on the biochar characteristics and the pyrolysis products composition are numerous. However, there are limited findings of these parameters with palm kernel shell (PKS) as the biomass. This study focusses on the effect of the pyrolysis temperature and residence time of PKS on the yield of biochar produced and the biochar physio-chemical properties. The results showed that biochar yield decreased as the peak temperature and residence time increased. This finding is consistent with the findings by other researchers. However, those factors do not have distinct influence on biochar’s carbon content as found in other study which the peak temperature has the bigger impact instead of residence time. The effect of peak temperature or residence time on grindability; i.e. particle size of biochar after wet ball milled is insignificant. Smaller size of biochar may improve its function as reinforcing filler. As a conclusion, the optimum setup of pyrolysis is needed for a balance production in yield and biochar’s properties. It is recommended to produce biochar at higher peak temperature and shorter residence time to increase the total production. Additional analysis e.g. physical testing on the final polymer product can be used to investigate the effect of pyrolysis peak temperature and residence time.

The Effect of Peak Temperature on HAZ Microstructure and Toughness of V- and Nb-Bearing Microalloyed Steels

Welding heat cycle processes of V- and Nb-bearing microalloyed steels at different peak temperatures (1350, 1100, 950, 800 and 650 °C) were simulated by Gleeble 3500. The microstructure and toughness of two steels were investigated by optical microscopy (OM), scanning electron microscopy (SEM) and low-temperature impact toughness test (− 40 °C). The results indicated that the microstructure of both V and Nb steels consisted of the lath bainite (LB), granular bainite (GB), polygonal ferrite (PF) and a small amount of martensite austenite (MA) islands at 1350 °C, and acicular ferrite (AF) was also observed in V steel. Ferrite (F) phase became uniform, and hard phase LB decreased with the decrease in peak temperature. Impact tests indicated that both the two steels exhibited the best impact toughness (32.23 and 30.90 J) at the peak temperature of 950 °C. The impact toughness of V steel was better than of Nb steel all the time, which was consistent with the analysis of microfracture.

Effect of Peak Temperatures on Corrosion Behavior of Thermal Simulated Narrow-gap Weld Q690 High Strength Steel

Effect of Peak Temperatures on Corrosion Behavior of Thermal Simulated Narrow-gap Weld Q690 High Strength Steel

Microstructural Evolution and Softening Behavior of Simulated Heat-Affected Zone in 2219 Aluminum Alloy

The effect of peak temperature (T p) at 200, 300, 400, 500 and 550 °C on the microstructural evolution and softening behavior of the simulated heat-affected zone (HAZ) was studied in the 2219-T87 alloy by electron-backscatter diffraction, transmission electron microscopy, X-ray diffraction, micro-hardness and micro-tensile tests. The results showed that the grain size in the HAZs at 200–500 °C was comparable, but the number density of the strengthening precipitates (GP zones/θ′) decreased with increasing T p. At a T p of 550 °C, the grain size significantly decreased and the distribution of the misorientation angles corresponded to the MacKenzie distribution. The GP zones/θ′ phase coarsened and translated into θ phases at T p values in the range of 200–400 °C. Increasing the T p to 500 °C and above, some θ′ phases translated into θ phases and others dissolved into the α-Al matrix which led to an increase in the solid solution strengthening. The reduction of the number density of the GP zones/θ′ was responsible for the softening behavior.

Effect of Peak Temperature on the Grain Growth in Simulated HAZ of Cr-Mo-V Steel(T24)

Effect of Peak Temperature on the Grain Growth in Simulated HAZ of Cr-Mo-V Steel(T24)

Effect of Temperature and Sheet Temper on Isothermal Solidification Kinetics in Clad Aluminum Brazing Sheet

Isothermal solidification (IS) is a phenomenon observed in clad aluminum brazing sheets, wherein the amount of liquid clad metal is reduced by penetration of the liquid clad into the core. The objective of the current investigation is to quantify the rate of IS through the use of a previously derived parameter, the Interface Rate Constant (IRC). The effect of peak temperature and initial sheet temper on IS kinetics were investigated. The results demonstrated that IS is due to the diffusion of silicon (Si) from the liquid clad layer into the solid core. Reduced amounts of liquid clad at long liquid duration times, a roughened sheet surface, and differences in resolidified clad layer morphology between sheet tempers were observed. Increased IS kinetics were predicted at higher temperatures by an IRC model as well as by experimentally determined IRC values; however, the magnitudes of these values are not in good agreement due to deficiencies in the model when applied to alloys. IS kinetics were found to be higher for sheets in the fully annealed condition when compared with work-hardened sheets, due to the influence of core grain boundaries providing high diffusivity pathways for Si diffusion, resulting in more rapid liquid clad penetration.

Thermal Simulation Study of CGHAZ Austenite Grain Growth Behavior of X80 Pipeline Steel

The effect of peak temperature on austenite grain size was investigated by using thermal simulation and OM, TEM analysis. Grains grow slowly below 1250°C, and dramatically grow up as the temperature exceeds 1350°C. The primary precipitates in X80 pipeline steel are TiN and NbC, TiN particles cannot absolutely dissolve in steel during holding for 2s at 1300°C.Although TiN particles exist in steel, they cannot hinder grain growth of CGHAZ during welding process. The phenomenon can be explained by Ostwald Ripening mechanism.

Predicting Solid-State Phase Transformations during Welding of Ferritic Steels

The current work presents the numerical analysis of solid-state transformation kinetics relating to conventional welding of ferritic steels, with the aim of predicting the constituent phases in both the fusion zone and the heat affected zone (HAZ) of the weldment. The analysis begins with predictions of isothermal transformation kinetics using thermodynamic principles, such that the chemical composition of the parent metal is the sole user-defined input. The data is then converted to anisothermal transformation kinetics using the Scheil-Avrami additive rule, including the effects of peak temperature and austenite grain growth. Subroutines developed for the Abaqus finite element package use the semi-empirical approach described to predict phase transformations in SA508 Gr.3 Cl.1 steel. To study the effect of the cooling rates and the ability of the current model to predict the final microstructure, two weld samples were subjected to autogenous beam TIG welds under a fast (TG5-F, 5.00 mm/s) and slow (TG5-S, 1.25 mm/s) torch speed. Model validation is carried out by direct comparison with microstructural observations and hardness measurements (via nanoindentation) of the fusion and heat affected zones in both welds. Excellent agreement between the measured and predicted hardness has been found for both weld samples. Additionally, it is shown that the correct identification of the partial austenisation region is a crucial input parameter.