Effect Of Cooling Rate Research Articles

Effect of Cooling Rate on Phase Transformation and Strain Response of SA508-3 Steel by Numerical and Experimental Study

Abstract The key to accurately predict welding residual stress is to explore the solid-phase transition law of SA508-3 steel and establish the phase transition model under continuous cooling conditions. The effects of cooling rate on phase transformation and strain response of SA508-3 steel were investigated in this paper. The established programs accurately predict the evolution of microstructure at different cooling rates, the relationship between the bainite volume fraction and temperature is fitted by a modified bainite transformation model and is validated by optical microscopy and dilatometric test. The strain evolution of SA508-3 steel is predicted at different cooling rates and is verified by the dilatometric test. In addition, the effects of bainite transformation and martensite transformation on the strain response of SA508-3 steel are intensively discussed. This work casts light on the simulation of metallurgical effects at different cooling region during welding.

Effects of Grain Size, Cooling Rate, and Sample Preparation on the Phase Transition from Protoenstatite to Clinoenstatite

ABSTRACT X-ray diffraction experiments were carried out with protoenstatite, chemical composition Mg2Si2O6, in order to clarify the conditions under which protoenstatite can be retained at room temperature. Our results show that grain size, cooling rate, and shear stress during sample preparation clearly affect the transition from protoenstatite to clinoenstatite. Smaller protoenstatite grains were more likely to be retained, and the relationship between the retained volume ratio of the protoenstatite and grain size was statistically consistent with martensitic nucleation. The most protoenstatite was retained in the experiment using a cooling rate of 3 °C/min; the retained volume ratio decreased in experiments with both faster and slower cooling rates. The martensitic transformation of protoenstatite to clinoenstatite is promoted by shear stress caused by a fast cooling rate. Shear stress caused by grinding and polishing also promotes the transformation, but ion milling, used to prepare samples for transmission electron microscope observation, leaves the protoenstatite unchanged. Therefore, samples including protoenstatite should be prepared without producing shear stress so that the protoenstatite can be observed.

Melt Cooling Rate Effect on the Microstrucutre of Al–Si Alloy Doped with Mg, Mn, Fe, Ni, and Cu

Melt Cooling Rate Effect on the Microstrucutre of Al–Si Alloy Doped with Mg, Mn, Fe, Ni, and Cu

Effect of Grain Size and Cooling Rate on the Martensite Start Temperature of Stainless Steel

Herein, the transformation process of the martensitic stainless steel under different austenite temperatures, holding times, and cooling rates were in situ observed using the confocal laser scanning microscope. The grain boundary migration energy of the austenite grain was 241.51 kJ mol−1. The grain size at different temperatures and holding times was predicted, agreeing well with measured values. The relationship between the martensite start temperature and the grain size is proposed. The martensitic start temperature was significantly influenced by the cooling rate. With the increase of the cooling rate, the martensitic start temperature first decreased then rose up due to the quenching vacancy and internal stress, respectively.

Cooling rate effects on luminescence and structure properties of the 5CB liquid crystal, doped by different nanoparticle dispersions

The effect of the 5CB liquid crystal cooling rate on its luminescence spectra at the low temperature (T = 4.2 K) has been found and studied for two types of nanocomposites: 5CB liquid crystal, doped by carbon nanotubes (NT) or so-called hybrid nanoparticles (NT + OMMT). Hybrid nanoparticles were prepared from organomodified layered montmorillonite minerals (OMMT) with the addition of carbon nanotubes. Experiments have been carried out at two cooling rates, 2 and 10 K/min. Structure of the luminescence spectral bands is associated with 5CB crystallization peculiarities and formation of its glass-like state under different cooling regimes of the isotropic phase. The reasons for the short-wavelength shifts of the luminescence peaks for the 5CB–(NT + OMMT) sample compared to the 5CB–NT one are discussed.

Effect of Cooling Rate on Microstructure, Microporosity, and Segregation Behavior of Co-Al-W Alloys Prepared by Vacuum Induction Melting

Effect of Cooling Rate on Microstructure, Microporosity, and Segregation Behavior of Co-Al-W Alloys Prepared by Vacuum Induction Melting

Investigating the effect of cooling rate on strength of Fused Filament Fabrication parts using differential scanning calorimetry technique

Desired mechanical properties are major area of interest within the field of Additive Manufacturing (AM) technologies. Fused Filament Fabrication (FFF) is an extrusion-based AM technique. In FFF process, the primary concern of strength is bonding between strands,and it is greatly influenced by the heat transfer during the manufacturing process. The extent of bonding not only influences the strength, but also the structural integrity of the part. To study the bonding between the extruded polymer strands of FFF process, investigation must be done to understand the influence of rate of cooling during FFF process. The present study focuses on investigation of cooling rate effects on FFF-ABS (Acrylonitrile Butadiene Styrene) parts over their tensile strength. Since glass transition temperature plays a key role in understanding the history of the thermal behavior, it is hence important to estimate its value for various extrusion temperatures. To understand this, glass transition temperature is estimated through Differential Scanning Calorimetry (DSC) experimentation technique as it records the thermal history of the polymer and hence this test is applied at different cooling rate. Additionally, to support the DSC graphs, tensile testing of FFF made parts is done on the parts manufactured at two extreme extruder temperatures namely 230° C and 250° C. Better bond formation between the strands contributes to higher strength and hence neck growth is estimated by capturing the scanning electron microscope graphs. The higher strength (as obtained for higher neck growth)is due to higher or proper cooling process. The results also show that the parts cooled at higher cooling rate have better bonding in terms of neck growth which proves a good agreement among the cooling rate, strength, and neck growth. The novelty of this work lies in polymer characterization to provide more insights in FFF layer deposition process (effect of different cooling rate on FFF process) using DSC and mechanical testing/analysis.

Effect of Cooling Rate on Carbide Characteristics of the High Vanadium High-speed Steel

Effect of Cooling Rate on Carbide Characteristics of the High Vanadium High-speed Steel

Effect of Cooling Rates and rapidly quenched on Al-Si alloy

Due to its unique properties, the material could be applicable in the automotive industry for the manufacture of exhaust valves, for wear parts, and probably as a material for selected aggressive chemical environments. The solidification behavior of the Al-80.5 % Si-19.5 (A), Al-79% Si21% (B) and Al-77.5 % Si-22.5 % (C) alloys at slowly cooling and Rapidly quenched are reported and discussed. The samples were characterized by X-ray diffraction to calculated lattice constant, optical microscopy and mechanically by (Tensile test, and Hardness) in order to evaluate the response of the heat treatment on the different starting microstructures and mechanical properties.It was found that the lattice parameters for all Si contents decreases with increasing Si content in the solid solution. All mineral compounds formed during hardening were examined by optical microscopy. The highest maximum tensile strength was 120 MPa in the sample Al-22.5Si (Slowly cooled) and 126MPa in the sample Al-22.5Si (rapidly quenched) in the same weight, and highest hardness was 77 HB in the sample Al-22.5Si (Slowly cooled), and 81 HB in the sample Al-22.5Si (rapidly quenched).

Effect of Cooling Rate and Nb on the Microstructure and Hardness Variation in Microalloying Medium-Carbon Non-Quenched and Tempered Steel Simulated in a Die Forging Process

Effect of Cooling Rate and Nb on the Microstructure and Hardness Variation in Microalloying Medium-Carbon Non-Quenched and Tempered Steel Simulated in a Die Forging Process

The Effect of Cooling Rate on the Microstructure Evolution and Mechanical Properties of Ti-Microalloyed Steel Plates.

Ti-bearing microalloyed steel plates with a thickness of 40 mm were subjected to ultra-fast cooling (UFC) and traditional accelerate cooling after hot-rolling, aiming to investigate the effect of cooling rate on the microstructure and mechanical properties homogeneity, and thus obtain thick plates with superior and homogeneous mechanical properties. Yield strength, tensile strength, and elongation were 642 MPa, 740 MPa, 19.2% and 592 MPa, 720 MPa and 16.7%, respectively, in the surface and mid-thickness of the steel with ultra-fast cooling, while in the steel with traditional accelerate cooling, 535 MPa, 645 MPa, 23.4% and 485 MPa, 608 MPa, 16.2% were obtained in the surface and mid-thickness of the plate. The yield strength has been greatly improved after UFC, for the refinement of grain and precipitates produced by UFC. In addition, the equivalent grain size and precipitates size in the thick plate with UFC are homogeneous in the thickness direction, leading to uniform mechanical properties. The crystallographic characteristics of different precipitates have been studied. The precipitates formed in the austenite deformation stage obey Kurdjumov–Sachs orientation relationship with the ferrite matrix, while the fine precipitates formed in the ferrite obey [112]MC//[110]α and // orientation relationship with the ferrite matrix.

The Effect of Cooling Rate on Structure, Basic Mechanical and Special Properties of Complex Alloyed Manganese Cast Iron

The results of the study of the cooling rate effect on the structure and properties of castings for parts of equipment made of complex alloyed manganese cast iron, which operate under conditions of abrasive and impact-abrasive wear, are presented. The properties and characteristics of microstructures of samples from the investigated cast iron composition for different cooling rates are given: relative and impact-abrasive wear resistance, hardness, volume fraction of the carbide phase, and the average size of carbides. It is shown that the cooling rate (as well as the chemical composition of cast iron) is a determining factor in the primary microstructure formation that affects the properties of castings.

A methodology for predicting processing induced thermal residual stress in thermoplastic composite at the microscale

A computational finite element (FE) model of thermal residual stress was developed for carbon fiber/thermoplastic composites at the microscale and implemented via user material subroutine (UMAT) in ABAQUS. This model accounts for cooling-rate effects on crystallinity and stress-free temperature, temperature-dependent elastic modulus, temperature-dependent coefficient of thermal expansion (CTE) of the matrix, and the temperature-independent transversely isotropic properties of the carbon fiber. Results are generated for a model composite, consisting of a single carbon fiber embedded in a polypropylene thin film. Single filaments are pre-tensioned in the polymer melt to induce different levels of residual axial strain as well as maintain straight fibers during cool-down. Three different preload conditions (1g, 4g, and 8g) were experimentally fabricated and modeled. The residual strain along the length of the fiber is quantified and validated including the shear lag region that develops at the free edge of the sample. Experimentally measured residual strain shows a good correlation with the FE predictions for the applied fiber preloading conditions.

Effect of Solution Treatment and Cooling Rate on the Microstructure and Hardness of Ti-6Al-4V Alloy Manufactured by Selective Laser Melting Before and After Hot Isostatic Pressing Treatment

This paper extends our previous work to investigate the effect of heat treatment on the microstructure of Ti-6Al-4V fabricated by selective laser melting. A post-heat treatment at 930 °C for 15 min followed by three cooling rates before and after hot isostatic pressing (HIP) treatment was applied. The findings illustrated that the microstructure of the quenched samples before the HIP treatment was characterized by a mixture of α + α′ phase with a microhardness value of 336 ± 6 HV0.3. Air cooling produced a structure dominated by the α phase, with ~ 7.5% of the β phase and a microhardness value of about 330 ± 4 HV0.3. Furnace cooling led to a mixture of α phase and ~ 17% of the β phase and hardness of 327 ± 6 HV0.3. After HIP followed by post-heat treatment, acicular α′ martensite with microhardness value 377 ± 2 HV0.3 dominated the quenched specimen microstructure. Following air cooling, the microstructure consisted of a mixture of α-lamella and β with some needles of the α with a microhardness value of 336 ± 3 HV0.3. In the case of the furnace cooling, a complete transformation of β to a mixture of α + β phase was observed. The β volume fraction formed in the microstructure was estimated at ~ 8.5%, having microhardness 322 ± 4 HV0.3. Reasons for such behaviors are discussed.

Effect of Cooling Rate on Phase Transformation Behavior during Isothermal Annealing of SCr420 Steel

Herein, the effect of cooling rate on microstructure formation and phase transformation behaviors during isothermal annealing of the SCr420 steel is investigated. During isothermal annealing, tempering is performed after normalizing, and the effect of cooling conditions from normalizing to tempering is analyzed. As the cooling rate increases, the nonuniform microstructure with the band structure formed after hot forging tends to be homogenized. When the temperature reached during cooling is lowered, the phase transformation is rapidly completed during the cooling process, and the microstructure becomes more homogeneous. Phase transformation behavior during cooling from the normalizing temperature is analyzed through differential scanning calorimetry. Two exothermic reaction peaks are detected, and those peaks are related with the γ → γ + α → α + θ phase transformation. The higher the cooling rate, the lower the phase transformation starting temperature and the higher the phase transformation rate. In addition, from the thermal analysis data, the phase transformation kinetics and activation energy during cooling are analyzed by the Friedman method and the additivity rule. Through this analysis, the Avrami exponent and the activation energy for the phase transformation are derived.

The Effect of Cooling Rate on the Microstructure and Hardness of As-Cast Co-28Cr-6Mo Alloy Used as Biomedical Knee Implant

The Effect of Cooling Rate on the Microstructure and Hardness of As-Cast Co-28Cr-6Mo Alloy Used as Biomedical Knee Implant

Effect of Cooling Rate during Thermal Processes on the Electrical Properties of Cast Multi-Crystalline Silicon

Photoluminescence (PL) imaging techniques and the minority carrier lifetime test system were employed to investigate the variation of the interstitial iron (Fei) concentration, the recombination activity of structural defects and the minority carrier lifetime of cast multicrystalline silicon (mc-Si) in response to the cooling rate after heating. The results showed that when the mc-Si wafers are heated to high-temperature (1000 °C) and then cooled to ambient temperature with different cooling rate, the Fei concentration, the number of recombination active dislocations and grain boundaries increased as the cooling rate rises while the minority carrier lifetime decreased. If cast mc-Si is heated followed by faster cooling at 30 °C/s, the Fei concentration increase by 223% and the electrical activity of grain boundaries, dislocations and intragrain increase significantly, that is to say, the whole wafer is heavily contaminated with metal impurities, and present extremely low minority carrier lifetime.

Effect of Cooling Rate on the Microstructure Evolution and Mechanical Properties of Iron-Rich Al-Si Alloy.

The mechanical properties of iron-rich Al–Si alloy is limited by the existence of plenty of the iron-rich phase (β-Al5FeSi), whose unfavorable morphology not only splits the matrix but also causes both stress concentration and interface mismatch with the Al matrix. The effect of the cooling rate on the tensile properties of Fe-rich Al–Si alloy was studied by the melt spinning method at different rotating speeds. At the traditional casting cooling rate of ~10 K/s, the size of the needle-like β-Al5FeSi phase is about 80 μm. In contrast, the size of the β-Al5FeSi phase is reduced to 500 nm and the morphology changes to a granular morphology with the high cooling rate of ~104 K/s. With the increase of the cooling rate, the morphology of the β-Al5FeSi phase is optimized, meanwhile the tensile properties of Fe-rich Al–Si alloy are greatly improved. The improved tensile properties of the Fe-rich Al-Si alloy is attributed to the combination of Fe-rich reinforced particles and the granular silicon phase provided by the high cooling rate of the melt spinning method.

Effect of Cooling Rate on Growth Mechanism of Primary Α and Precipitation of Secondary Α of a Near Α Titanium

Effect of Cooling Rate on Growth Mechanism of Primary Α and Precipitation of Secondary Α of a Near Α Titanium

Effects of Cooling Rate and Holding Temperature on the Modification and Purification of Iron-Rich Compounds in AlSi10MnMg(Fe) Alloy

Effects of Cooling Rate and Holding Temperature on the Modification and Purification of Iron-Rich Compounds in AlSi10MnMg(Fe) Alloy