Transmission of Sound in Molten Metals

Webber, G.M.B.; Stephens, R.W.B.

doi:10.1016/b978-0-12-395664-4.50014-6

Cited by 23 publications

(5 citation statements)

References 66 publications

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“…It is noted that for pure Al and tin the huge velocity drop from the solid to liquid state has been reported in[9] and[10], respectively. Because the ultrasonic attenuation in metals at 10 MHz is not high either in the solid or liquid state[11], during the heating (not cooling) cycle the attenuation jump does not appear to be very high near the solid-liquid transition stage[10]. At present, for metals, it appears that there is no report of ultrasonic attenuation measurement during the cooling (liquid to solid) cycle.…”

mentioning

confidence: 93%

Ultrasonic evaluation of semi-solid metals during processing

Jen

Liaw

Chen

et al. 2000

Meas. Sci. Technol.

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Ultrasonic velocity and attenuation measurements for three different semi-solid (SS) aluminum (Al) alloy billets (A356, A357 and 86S) and one dendritic sample (A356) were performed in the temperature range between room temperature and ~575 °C using a non-contact laser-ultrasonic technique. It was found that there are measurable differences in ultrasonic velocity and attenuation between SS and dendritic samples and these differences are larger as the temperature becomes closer to the complete melt state. In a laboratory setup simulating the barrel section of a thixomoulding or a rheomoulding machine, a clad buffer rod (high temperature probe) was used to perform real time ultrasonic monitoring. We have observed 10 MHz ultrasonic signals of 30 dB signal-to-noise ratio reflected from a rotating screw with a distance of 5.5 mm between the probe end and the root of the screw in a viscous liquid Al alloy (A356) at 610 °C. This information should enable us to determine whether the processed part has the desired thixotropic structure or not, and then to properly adjust heating and other process parameters.

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confidence: 93%

Ultrasonic evaluation of semi-solid metals during processing

Jen

Liaw

Chen

et al. 2000

Meas. Sci. Technol.

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“…For liquid metals the contribution of heat conductivity to sound absorption is comparable to that of the viscosity and needs to be taken into account [5]. Calculations have been performed for liquid mild steel at 1900K with the following values: η = 0.004P a − s; κ = 28.4W/m/K; C P = 848.25J/kg/K, ρ = 6500kg/m 3 , c = 3600m/s (longitudinal).…”

Section: Estimation Of Frequency Attenuation In the Weldmentioning

confidence: 99%

Enhancing real-time ultrasound signatures of molten nugget growth for quality evaluation of resistance spot welds

Karloff

Chertov

Maev

2009

2009 IEEE International Ultrasonics Symposium

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This paper presents an effective means of enhancing weak acoustic reflections in real-time ultrasound signatures of a spot weld, by analyzing the propagation of acoustic waves through the electrodes and heated weld region. A new method of processing the ultrasound data is presented that removes undesired acoustical reflections in the electrode cap and enhances weak reflections at the solid-liquid interface. To facilitate this, frequency and amplitude attenuation resulting from the weld medium and acoustical interfaces of the layered weld structure are examined. Sources of echoes that destructively interfere with the desired reflections are also identified and removed by optimal filter design. Finally, basic image processing techniques are applied to a B-scan representation of the weld to improve visualization of the liquid nugget during cooling. This additionally permits the accurate measurement of the final weld thickness; an important quality control parameter.

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“…To get a preliminary estimate of the relative importance of those effects for the acoustic resonator performance, we have collected acoustic and material properties for liquid gallium and liquid aluminum in Tables I and II. [11][12][13][14][15][16][17] Necessary data on tube and termination materials are given in Table III. [17][18][19] Among other familiar quantities, the effective shear viscosity…”

Section: Problem Statementmentioning

confidence: 99%

Resonant oscillation of a liquid metal column driven by electromagnetic Lorentz force sources

Makarov

Ludwig

Apelian

1999

The Journal of the Acoustical Society of America

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In this paper, a theoretical study is conducted in order to establish the feasibility of a liquid metal acoustic resonator (liquid gallium or liquid aluminum) for high-amplitude acoustic oscillations. The fundamental resonant frequency typically lies between 5 and 40 kHz. The oscillations are induced by an alternating Lorentz force density applied directly to the liquid metal volume. Depending on the boundary conditions, two different resonator types (open–closed and open–open) are theoretically investigated. The analysis incorporates the effects of impedance termination, volume absorption, wall friction, acoustic radiation from the open end, and nonlinear inflow–outflow losses. The actual elasticity of the container, either a ceramic or quartz tube, and the coupled solid–liquid interactions are taken into consideration. Based on this investigation, theoretical predictions are conducted for the quality factor and the pressure level for the liquid metal resonator under various geometric and boundary conditions. They indicate that resonant amplitudes of 10–20 atm can be achieved using commercially available high-current audio amplifiers.

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Transmission of Sound in Molten Metals

Cited by 23 publications

References 66 publications

Ultrasonic evaluation of semi-solid metals during processing

Ultrasonic evaluation of semi-solid metals during processing

Enhancing real-time ultrasound signatures of molten nugget growth for quality evaluation of resistance spot welds

Resonant oscillation of a liquid metal column driven by electromagnetic Lorentz force sources

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