Effect Of Cooling Process Research Articles

Effect of Cooling Process on Microstructure and Properties of Low Carbon Bainite Steel

This article used Mn-Mo-Cr-B low-carbon bainitic steel as the experimental material. The continuous cooling transformation curve of the steel during continuous cooling was determined using a Gleeble-1500D thermal simulation test machine, and a corresponding phase transformation model for bainitic steel during continuous cooling was established. The influence of different cooling rates and final cooling temperatures on the microstructure and mechanical properties of the steel was investigated. Employing metallography, SEM, and EBSD techniques, the microstructure, crystallographic orientation, and grain boundary angle distribution of the low-carbon bainitic steel were explored, and their relationship with the steel's strength and toughness was studied. The research findings reveal that varying cooling rates and final cooling temperatures impact the phase transformation process and microstructure of the steel, consequently affecting its mechanical properties indirectly. With increasing cooling rate, the diffusion and fineness of martensite increase, and the quantity of lath bainite grows while the laths become finer. Elevated final cooling temperatures lead to larger martensitic-austenitic (MA) islands and reduced lath bainite quantity, causing the laths to become wider. Through analysis of the substructure of bainitic steel, it was determined that the bainite organization in the tested steel comprises primary austenite grains, lath packet, and lath block in succession. Lath packets are composed of lath blocks with different orientations, where lath size predominantly controls strength. Finer lath size corresponds to higher strength, and the influence of substructure on toughness is comparatively minor.

Effects of Cooling Process on GaN Crystal Growth by Na Flux Method

The effects of cooling on the yield (percentage of Ga in the original melt that is incorporated into the GaN crystal) and morphology of GaN crystals grown by the Na flux method have been investigated. Yields of pyramidal GaN crystals of up to 94.9% were obtained by spontaneous crystallization using the slow cooling method. A lower cooling rate contributed to higher yield of GaN crystals. Scanning electron microscopy observations indicated that the crystalline perfection increased as the cooling rate was decreased. Instabilities such as macrosteps, cellular structures, and hopper crystals (a form of crystal defined by its “hoppered” shape) were observed after crystal growth at higher cooling rates. These results suggest ways to improve the yield and control the growth of perfect GaN crystals.

Effect of Cooling Process on Microstructure and Mechanical Properties of X100 Pipeline Steel

Effect of Cooling Process on Microstructure and Mechanical Properties of X100 Pipeline Steel

Effect of Cooling Process on Porosity in the Aluminum Alloy Automotive Wheel During Low-Pressure Die Casting

Experiments were conducted to verify the feasibility of cooling process for one aluminum alloy wheel during low-pressure die casting, and the results showed there were some macroporosity defects in the junctions of small spokes. Numerical simulation was implemented, and the rational cooling and insulation process was determined by analyzing the solidification times of different stages at some locations of casting. The simulation and experimental results both demonstrated the insulation spots had a good effect on prolonging solidification time at the location with thin wall thickness, preventing the feeding paths cutoff prematurely and decreasing the size of porosity defects distinctly.

Effects of Cooling Processes on Microstructure Evolution of X80 Pipeline Steel

With the development of pipeline industry, the pipeline steels with higher strength and plasticity, better low-temperature toughness and weldability are the main development trend. For bainitic pipeline steels, M/A constituent is the main hard phase. Although the M/A constituent can enhance the strength, the larger block-form M/A constituent can deteriorate low-temperature toughness. Therefore, it is essential to further investigate how to refine the M/A constituent. In the present paper, X80 pipeline steel was cooled to room temperature with various cooling paths after hot compression deformation at the temperature of 800oC. The evolution of microstructure of X80 pipeline steel has been analyzed by optical microscope (OM) and scanning electron microscope (SEM). The experimental results show that increasing the cooling rate can significantly refine M/A constituent and promote the formation of granular bainite, and the bainitic ferrite can be also greatly refined. In addition, the effects of five final temperatures of fast cooling were also investigated.

Effects of Cooling Processes on Structural Changes for an Au24Cu19 Alloy Cluster

Effects of Cooling Processes on Structural Changes for an Au24Cu19 Alloy Cluster

The Effect of Cooling Process on the Microstructure and Electrical Transport Properties of AgSbTe<sub>2</sub> Compound

AgSbTe2 compounds have been synthesized via melting and subsequent cooling processes. The effect of cooling process, from air-cooling, water quenching to liquid nitrogen-quenching, on the microstructure and the electrical transport properties of AgSbTe2 has been investigated by means of powder X-ray diffraction, electron microscope, electrical resistivity, and Hall coefficient measurements. It has been found that the cooling process has apparent influence on the microstructure and corresponding electrical properties. The phase components and morphology changed as the cooling process altered. The electrical resistivity and the Seebeck coefficient of the as-prepared samples increased from air-cooled to liquid nitrogen-quenched sample.

Effect of Cooling Process on Critical Current Density of Bi-2223/Ag Superconductive Tapes Prepared by Dip-Coating

Effect of Cooling Process on Critical Current Density of Bi-2223/Ag Superconductive Tapes Prepared by Dip-Coating

Effect of Cooling Process on Critical Current Density of Bi-2223/Ag Superconductive Tapes Prepared by Dip-Coating

In this paper, effect of the cooling process is examined for the superconductive properties of high T c Bi-2223/Ag tapes prepared by dip-coating. The short tapes are cooled after the isothermal heat treatment at a controlled temperature profile, which can refine the microstructure. The cooling rate and the slow cooling range are varied, showing that the optimum condition is found where the enhanced J c is obtained compared to that of normal furnace cooling. Contrarily, T c did not show an optimum under this condition but increased monotonously with a decrease in the cooling rate and an increase in the slow cooling range. From phase identification, microscopic observation, and quantitative analysis, the microstructure formation in the polycrystalline oxide layer during this process and its relation to these properties are discussed.