Pre-heat Treatment Temperature Research Articles

Influence of Pre-Weld Heat Treatment and Aging Post-Weld Heat Treatment on Tensile Test and Microstructure of Aluminium 6061 Weld Joint

Aluminium 6061 is an aluminium composition with Al-Mg-Si alloy which is often used for offshore structure material due to its high strength, good ductility and good corrosion resistance as well as its mechanical properties that can be enhanced by heat treatment. The purpose of this paper is to show the effect of heat treatment variations, in the form of preheating and aging PWHT, on tensile strength and microstructure of aluminium 6061 welding connection with GTAW process using electrode ER 5356. The pre-heat temperature variations used were 80°C, 100°C, and 120°C and the aging PWHT temperature variations used were 180°C and 260°c. The result shows that specimen with preheat treatment temperature of 120°C and aging pwht temperature of 260°C had the largest ultimate strength of 246.74 MPa and yield strength of 125.21 MPa. The highest percentage of Mg2Si formed was also found on the same specimen with a percentage of 48.84% in weld metal, 58.75% in HAZ, and 43.54% in base metal.

Preparation of High-Purity Aluminum Oxide via Mechanochemical Oxidation of Aluminum in a 0.1 M KOH Solution, Followed by Chemical and Heat Treatments

We have examined the feasibility of preparing high-purity aluminum oxide by oxidizing granulated aluminum in a 0.1 M potassium hydroxide solution, followed by heat and acid treatments of the oxidation products. The aluminum oxidation product, consisting of two phases of Al(OH)3 (bayerite and gibbsite), was first heat-treated at temperatures of 300, 600, 900, and 1200°C; then treated with hydrochloric acid; and calcined at a temperature of 1450°C. It has been shown that raising the preheat treatment temperature increases the total concentration of impurities, including Fe impurities, but reduces the concentration of alkali metals (K, Na, and Li). Using 99.7%-pure aluminum, we have prepared aluminum oxide with a purity at a level of 99.886%. Using 99.98%-pure aluminum, we have obtained aluminum oxide with a purity at a level of 99.993%.

Investigation of the Lithium-Containing Aluminum Copper Alloy (AA2099) for the Laser Powder Bed Fusion Process [L-PBF]: Effects of Process Parameters on Cracks, Porosity, and Microhardness

In order to widen the alloy spectrum for the laser powder bed fusion process, apart from the popular Al-Si-based alloys, AlSi10Mg and AlSi12, the precipitation-hardenable AA2099 wrought alloy has been considered in this work. The effect of varied laser power, scanning speed, a preheated base plate (in situ heat treatment) and post-heat treatments on porosity, cracks and microhardness was observed. The results indicate a successfully printed crack-free part with very minimal porosity at 90 W laser power and 550 mm/s scanning speed with microhardness of 72 HV0,1 at a 520°C preheat treatment temperature. The influence of added titanium aluminide powder in crack removal and grain refinement is also reported in this work.

Preparation and performance of a cold gas dynamic sprayed high-aluminum bronze coating

By mixing preheated high-aluminum bronze powders with different amounts of Al2O3 powder, a low-pressure cold-sprayed coating was prepared and sprayed onto a Cr12MoV steel substrate. The hardness of the coating and the bonding strength between the coating and the substrate were tested with a HV-1000 microhardness tester and a mechanical universal testing machine. The surface microstructure, cross-section and tensile fracture surface of the coating were observed with a scanning electron microscope (SEM). Correspondingly, the influences of the preheat treatment temperature of the bronze powder and the Al2O3 content on the coating performance were investigated. The results indicate that the hardness of bronze powders decreased and the coating deposition rate increased after the preheating treatment of the bronze powder. The Al2O3 content in the mixed powders contributed to the deformation of bronze powders during the spraying process. This trend resulted in varied performance of the coating.

Optimising emulsion stability during processing of model infant formulae using factorial statistical design

This study examined the effects of total solids (TS), preheat treatment temperature, and first‐ and second‐stage homogenisation pressures on the stability of model infant formula emulsions, using factorial statistical design. Oil droplet size decreased with increasing first‐ and second‐stage homogenisation pressures. The viscosity of emulsions after homogenisation was mainly affected by TS. Spray drying altered the protein profile of the interfacial layer around oil droplets compared to that posthomogenisation, but did not alter oil droplet size. This work made it possible to select optimum conditions to produce a stable infant formula emulsion, with the use of lower homogenisation pressures.

Network Carbide Inheritance during Heat Treatment Process of Large Shield Machine Bearing Steel GCr15SiMn

Network carbide inheritance during heat treatment process of large shield machine bearing steel GCr15SiMn was investigated by heat treatment experiments and quantitative metallographic. Samples with the proeutectoid cementite network thickness in the range of 0.19~0.54 μm were obtained by changing austenitizing temperature and soaking time of pearlite transformation. The results show that the network in hot rolled bar can be improved when the pre-heat treatment temperature is 950 °C. When the network thickness is above 0.40 μm, the undissolved cementite networks present in microstructures after quenching and tempering. In a Chinese standard, the network grades are 1.5 and 3.0 degree when the networks thickness are 0.40 μm and 0.54 μm, respectively. The critical network thickness that can be eliminated by heat treatment is 0.29 μm.

The study of aluminum loss and consequent phase transformation in heat-treated acid-leached kaolin

This study investigates the effect of Al leaching during Fe removal from kaolin to mullite. Heat-treated kaolin was obtained by heating natural kaolin at 400, 500, 600, 700, 800 and 900 deg. C. The heat-treated kaolin was then leached at 100 deg. C with 4 M, 3 M, 2 M, 1 M, 0.2 M solution of H{sub 2}SO{sub 4} and 0.2 M solution of oxalic acid. The dried samples were sintered to 1300 deg. C for 4 h at a heating rate of 10 deg. C min{sup -1}. X-ray diffractometry and differential thermal analysis were used to study the phase transformation of kaolin to mullite. It was found that 700 deg. C is the optimum preheat-treatment temperature to leach out Fe and also Al for both types of the acids used. The majority of the 4 M sulfuric acid-treated kaolins formed the cristobalite phase when sintered. On the other hand, 1 M, 0.2 M sulfuric acid and 0.2 M oxalic acid leached heat-treated kaolin formed mullite and quartz phase after sintering. - Research Highlights: {yields} Preheat-treatment of kaolin improves the leachability of unwanted iron. {yields} The optimum preheat-treatment temperature is 700 deg. C. {yields} Sintered 4 M sulfuric acid-treated kaolinmore » majorly formed the cristobalite phase. {yields} Sintered 0.2 M oxalic acid-treated kaolin formed lesser amorphous silicate phase.« less

STRUCTURAL AND OPTICAL PROPERTIES OF ZNO THIN FILMS PREPARED BY DIFFERENT SOL-GEL PROCESSES

ZnO thin films were prepared on quartz glass substrates by different sol-gel methods using a spin-coating technique. The structural and optical properties of ZnO thin films were studied by X-ray diffraction (XRD) and transmission spectra analysis. The results show that different factors such as Zn2+ concentration, solvent, sol stabilizer, pre-heat treatment temperature, and annealing temperature have a great impact on the structural and optical properties of ZnO thin films.

Feasibility of Using Heat Treated Wood in Wood/Thermoplastic Composites

Using wood and other natural fibers with thermoplastic materials is always associated with a problem: poor compatibility between wood fibers and thermoplastic matrix. This paper deals with the mentioned problem and tries to solve, or at least ease, it through pre-heat treatment of wood prior to blending of wood fibers with other components of composites. In this study, wood pre-heat treated at different temperatures (175, 190 and 205°C) was used at various loadings (25 and 50%) with high density polyethylene (HDPE) and polypropylene-maleic anhydride copolymer (MAPP) to produce composites. The composite properties, including mechanical performance and morphological character, were investigated. The results of this study show that pre-heat treatment temperature and coupling agent content did not impact the composite properties at 25% wood content. Adding treated wood at 50% level to the composites enhanced the mechanical properties in comparison with untreated wood. The degree of the enhancement depended on pre-heat treatment temperature. Using wood treated at 190°C resulted in composites with the highest modulus of rupture (MOR) and tensile strength. In terms of modulus of elasticity (MOE), composites having wood treated at 205°C showed the highest MOE in both tensile and flexural tests. Adding 2% coupling agent caused an improvement in modulus of rupture (MOR) and tensile strength. An increase in wood content from 25 to 50% deceased strain at maximum load drastically. Morphological study showed that the mode of fracture is a function of wood and coupling agent content, and pre-heat treatment temperature.

Effect of pre-heat treatment on the static and dynamic thermo-mechanical properties of ultra-high molecular weight polyethylene

In the present work, a dynamic thermo-mechanical analysis technique has been used to investigate the effect of pre-heat treatments on the visco-elastic properties of Ultra-High Molecular Weight Polyethylene (UHMWPE) as a function of frequency and temperature. These properties include storage modulus ( E′) and loss modulus ( E″). The UHMWPE specimens were pre-heated at 50, 80 and 100 °C for periods of 2 and 4 h, respectively. The effect of these pre-heat treatments on the quasi-static mechanical properties (Young's modulus, yield strength, fracture strength, ductility and micro-hardness) has also been investigated. Finally, the degree of crystallinity of the UHMWPE has been measured as a function of pre-heat treatment time and temperature. The results show a strong dependence of most of these properties on the degree of crystallinity which is a function of pre-heat treatment temperature and duration.

Preparation of Porous Alumina and Its Bending Strength

Dried boehmite gel was preheated at various temperatures below 800°C and they were pressed and formed into bars. Then they were sintered in the temperature range of 1500-1650°C. The porosity and the bending strength of these sintered bodies were affected by the preheat-treatment temperature of the boehmite gel. There was no change in the structure of the sintered bodies which were preheated at temperatures below 200°C. A sintered body at 1650°C gave a porosity of 40% and a high bending strength of 80MPa. The relation, σ=aρn was established between the bending strength (σ) and the density (ρ) of the sintered bodies. The exponent n in the above relation is the same and the factor a is different between these two starting samples, boehmite and intermediate alumina. The factor a is affected by the fractal structure of sintering body.

Influence of Preheat-treatment Temperature on Ground Raw Coke Powder for Fabrication of Carbon Solids

The influence of preheat-treatment temperature in the range of 475-900°C on properties of ground powder of a green petroleum coke was studied.From these ground coke powders with different preheat-treatment temperature, carbon solids were also prepared by compression under 2000kg/cm2 at room temperature and calcination at 1000°C for 1h.Properties of ground coke powder, such as particle shape, X-ray parameters and graphitizability, showed drastic changes at the preheat-treatment temperature about 550°C.Below 550°C, the ground cokes showed spherical appearance of particles, broadened (002) diffraction profile of X-rays, and also non-graphitizing character after heat-treatment at 2800°C.They were easily compacted and sintered at high temperatures without any binder.The calcined bodies thus prepared showed relatively high compressive strength of about 1500kg/cm2.