Effects Of Heating Parameters Research Articles

An equivalent heat source model for inducted heating forming with single-circuit inductor

ABSTRACT Induction line heating is a suitable method for plate bending in shipbuilding, and the rapid prediction of this forming process is required. However, the existing coupled magnetic-thermal prediction method is time-consuming and requires complicated modelling operation, which makes it difficult to rapidly estimate the thermal conduction of large-size ship hull plate bending. This paper proposes an equivalent heat source (EHS) model for a single-circuit inductor and establishes its quantitative relationship with heating parameters. First, based on a local yet accurate magnetic-thermal coupling model, an EHS model was constructed with three governing parameters. Second, the results with the EHS model were consistent with the experiments, while the thermal analysis was accelerated eight times over current magnetic-thermal coupling analysis. Finally, the effects of heating parameters - current, frequency, air gap and plate thickness on the three governing parameters were investigated, and the relationship between the heating parameters and the EHS model was identified with dimensional analysis.

Effects of rapid heating on non-equilibrium microstructure evolution and strengthening mechanisms of titanium alloy

In this paper, the effects of heating parameters, including temperature ranging from 900 °C to 1000 °C, heating rates ranging from 2 °C∙s−1 to 100 °C∙s−1, and 120 s soaking on the non-equilibrium microstructure evolution of Ti-6Al-4V alloy were studied. Microstructures after heating were characterized to reveal the mechanism of non-equilibrium phase transformation. Uniaxial tensile tests at room temperature were carried out to evaluate the effects of non-equilibrium microstructure on the mechanical properties. Results show that higher heating rate and lower temperature lead to lower β phase volume fraction and finer β grains. A transition region with element gradient forms in the αp grain near the αp/β phase boundary and transfers into β phase gradually during the heating. Rapid heating could confine the movement of the transition region, and therefore reduce the α→β transition and growth of the β phase. When the Ti-6Al-4V alloy was heated to 1000 °C at a rate of 50 °C/s and then quenched immediately, the tensile strength was improved by 19.5% and reached up to 1263.0 MPa with the elongation only decreasing from 13.6% to 9.6% compared with the initial material. The main strengthening mechanism is that the rapid heating in the single-phase region avoids the rapid growth of the β phase, which leads to fully fine martensite formation after water quenching.

Enhanced formability and forming efficiency for two-phase titanium alloys by Fast light Alloys Stamping Technology (FAST)

During hot stamping of titanium alloys, insufficient forming temperatures result in limited material formability, whereas temperatures approaching the β phase transus also result in reduced formability due to phase transformation, grain coarsening and oxidation during the long-time heating. To solve this problem, Fast light Alloys Stamping Technology (FAST) is proposed in this paper, where fast heating is employed. Effects of heating parameters on the formability and post-form strength were studied by tensile tests. Forming of a wing stiffener was performed to validate this new process. Results show that microstructure of TC4 alloy after fast heating was in nonequilibrium state, which could enhance ductility significantly compared with the equilibrium state. When TC4 alloy was first heated to 950 °C with heating rate of 100 °C/s and then cooled to 700 °C, the elongation at 700 °C was more than 3 times that of a slow heating rate with soaking. Nano-scaled martensite with high dislocation density transformed from β phase was observed under fast heating condition. A complex shaped wing stiffener was successfully formed from TC4 titanium alloy in less than 70 s including heating, transfer and forming, and the post-form strength was almost the same with the initial blank.

Theoretical Analysis of Parameter Optimization for Lower-Ionosphere Excitation ELF/VLF Waves Based on Chirp-BOK Modulated Heating

To improve the anti-interference for ELF/VLF communication based on modulated heating lower-ionosphere, chirp spread spectrum technology with strong anti-interference is combined with square wave amplitude modulation, a novel method of chirp-BOK modulated heating lower-ionosphere is proposed in this paper. On this basis, to improve the radiation efficiency of ELF/VLF, the effects of heating parameters (effective radiation power, pump frequency, polarization mode, modulation frequency, duty cycle, and bandwidth) on the radiation efficiency of ELF/VLF were analyzed. The results show that the radiation amplitude of ELF/VLF increases with the increase of effective radiation power, while the radiation efficiency increases first and then decreases; the X-mode is better than the O-mode; the radiation intensity of ELF/VLF decreases with the increase of pump wave frequency from 4MHz to 10MHz; the ELF/VLF equivalent dipole moments increase with the rise of modulation frequency from 500Hz to 5kHz; with the change of duty cycle from 10% to 90%, the dipole moments first increase and then decrease, and the optimal range of duty cycle is 40% to 70%; with the increase of bandwidth, the dipole moments are unchanged. Furthermore, the ELF/VLF dipole moments of square wave amplitude modulated heating ionosphere is unchanged before and after the chirp spread spectrum.

Characterization of pork bone soup odor active compounds from traditional clay and commercial electrical stewpots by sensory evaluation, gas chromatography–mass spectrometry/olfactometry and partial least squares regression

AbstractThe effect of heating parameters on pork bone soup flavor generation in electrical stewpot was investigated. Four sensory attributes including meaty, fatty, kokumi and off‐flavor were used to evaluate the sensory characteristics of different pork bone soups. Twenty‐nine odor active compounds were identified by direct‐time intensity method of gas chromatography–mass spectrometry/olfactometry (GC–MS/O). Only eleven of them were detected in both traditional clay and commercial electrical stewpots. One of the electrical stewpot samples showed good sensory characteristics compared with other samples and its corresponding heating parameters were as follows: heating rate of 2.419°C/min, constant temperature time of 20 min, low temperature of 80°C and its holding time of 50 min. Correlation analysis between sensory attributes and odor active compounds through Partial Least Squares Regression (PLSR) revealed that hexanal, octanal, 6‐methyl‐5‐hepten‐2‐one, 2‐nonanone, decanal, benzaldehyde, (E)‐2‐nonenal had significant correlation with the sensory attributes.

Numerical analysis and experimental research of triangle induction heating of the rolled plate

In shipyard, triangle heating technology with irregular multi-heating paths and highly concentrated heat input is used to form a curved plate, especially a concave type plate. Compared with line heating process with simple line segment path, its main purpose is to get a bigger contraction deformation at the plate edge. Hence, triangle heating technology is important for most shipyards to increase hull-forming productivity and study the automation. This paper focuses on the moveable triangle induction heating technology. An electromagnetic coupling finite element model is built to simulate the moveable triangle induction heating process and reveal the temperature characteristics and deformation behavior. The results of the simulation are compared with those obtained from experiments and show good agreement. It demonstrates that the numerical model used in this study is effective for simulating triangle heating for the steel plate forming process in shipbuilding. With the numerical model, the paper further investigates the effect of heating parameters on temperature and shrinkage deformation. These are traced here with a modified mechanical model whose results are in accord with the numerical results. This modified model can be applied to predict the edge shrinkage and explain the effect of heating parameters on transverse shrinkage.

Effect of heating parameters on laser welded tailored blanks of hot press forming steel

Al–Si coating on the hot press forming steel sheet is diluted and diffused into the weld metal during laser welding and successive hot press forming process. Even after the hot press forming process, Al was still not homogeneously distributed within the weld metal and partially ferritic structures in the weld metal were observed in the Al-rich zone. In this study, the effect of heating duration and temperature on microstructure was investigated utilizing two different laser beam diameters. When using the larger diameter laser beam during welding, a wider weld bead resulted in enhanced weld flow and mixing of Al within the welds and thereby increases the martensitic fraction in the weld metal. As the heating duration and temperature increase, the volumetric fraction of ferrite decreases and nearly full martensitic morphology could be achieved. The effect of Al and Si composition on phase transformation was also confirmed by the thermodynamic calculation.

Influence of thermal treatment media on characteristics of Al–Zn–Mg alloys

The effects of heating parameters on the hardness, electrical conductivity and the associated microstructure of Al − Zn − Mg casting alloys were investigated using optimum heat treatment conditions. The qualitative analysis and microstructure characterisation of Al–Zn–Mg casting alloys were applied using differential scanning calorimetric measurements and scanning electron microscopy. It was observed that the hardness of tb6 aged sample after water quenching is the highest. The results show that the electrical conductivity of the alloy increased continuously with increasing aging temperature and aging time. At temperatures of 135°C and 180°C of aging treatment, the hardness of the alloy increased and then reached the peak value at aging times of 16 and 4 h respectively. The differential scanning calorimetric curves of tb6 aged samples reflect the differences on the microstructures formed by different quenching media and aging temperatures.

Graphite “Filter Furnace” Atomizer with Pd–Mg Chemical Modifier for Direct Analysis of Foods Using Electrothermal Atomic Absorption Spectrometry

This paper presents the results of optimization of operation parameters, investigation of analytical characteristics, and the capabilities of a graphite “filter furnaceˮ (FF) atomizer with a Pd–Mg chemical modifier (CM) for the direct determination of trace amounts of Pb, As, and Cd in foods by electrothermal atomic absorption spectrometry (ET AAS). The effects of heating parameters of the furnace on atomic absorbance values of Pb, As, and Cd were investigated during the pyrolysis and atomization steps including the carrying out of the investigation in the presence of mineral and organic macrocomponents of the analyzed materials. It is shown that the use of the graphite FF atomizer and Pd–Mg CM provides a ~2-fold increase in sensitivity of ET AAS determination of the listed elements in comparison with a conventional heated graphite furnace with a platform as well as completely or significantly eliminate matrix effects including background absorbance. The obtained limits of quantification for Pb, As, and Cd in foods were 0.0015, 0.002, and 0.0001 mg kg−1, respectively. The reliability of the proposed method was checked using standard methods.

Effect of Heating Parameters on the Part’s Properties in Hot Stamping Process

In the automotive industry, the hot forming of high strength steels offers the possibility to obtain significant reduction of weight without affecting the structural performances of final products. Compared with conventional sheet metal forming, the proper design of hot stamping process chain requires the deep knowledge of both interface phenomena and material behavior at high temperatures in order to obtain the desired properties of final products in terms of microstructure and strength characteristics. The work presented in this paper aims at accurately evaluate the effect of heating parameters on the properties of final sheet components produced in hot forming operations. Different from that in the lab, all the samples and parts used for the experimental test were produced in the production line, which can objectively show the manufacturing properties and microstructure character of products in mass. Microstructure evaluation, hardness measurement and dimensional accuracy test after hot stamping were performed and considered. The best heating parameters for the researched hot stamping B-Pillar’s production were obtained through the above research.