On the formation of vapor film during quenching in de-ionized water and elimination of film boiling during quenching in natural sea water

Hsu, Shu-Han; Ho, Yuan-Hong; Ho, Ming-Xi; Wang, Jian-Chiuan; Pan, Ching‐Tsai

doi:10.1016/j.ijheatmasstransfer.2015.02.049

Cited by 74 publications

(11 citation statements)

References 21 publications

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“…Esta microestructura se forma durante el enfriamiento a 600°-250°C aproximadamente. En el caso de la bainita superior su morfología es predominantemente arborescente, mientras que la bainita inferior, la cual se forma a temperaturas próximas a la de transformación martensítica [10], tiene un aspecto similar al de la martensita con agujas alargadas de ferrita y delgadas placas de cementita. Estas placas son paralelas y forman un ángulo de 60° con el eje de las agujas de ferrita [2].…”

Section: Conductividad Térmicaunclassified

Evaluación de la dureza y microestructura del acero 1045 templado en sustancias refrigerantes no tradicionales

2016

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El tratamiento térmico de temple en los aceros al carbono, es una alternativa tecnológica que favorece el incremento de las propiedades mecánicas como consecuencia de la transformación micro estructural del material.Actualmente no existe una sustancia ideal, para la realización del enfriamiento durante el temple de aceros al Carbono, por lo tanto, el objetivo de este estudio se centra en verificar el comportamiento de la dureza y la microestructura que se obtienen durante el temple de un acero AISI 1045 utilizando como medios de enfriamiento agua, refrigerante de radiador y refrigerante para mecanizado industrial.Los resultados indican que el uso de refrigerante de radiador favorece la obtención de alta dureza en la región superficial (60HRC), así como la obtención de estructura martensítica. El uso de refrigerante para mecanizado favorece la obtención de durezas inferiores (52HRC), pero con la presencia de bainita en una matriz martensítica lo que favorece la tenacidad.

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Section: Conductividad Térmicaunclassified

Evaluación de la dureza y microestructura del acero 1045 templado en sustancias refrigerantes no tradicionales

2016

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“…Accurate measuring the parameters above mentioned is most critical in developing such technologies as firefighting by using flows with different additives [2], thermal treatment of waste water or industrial water [3], cooling heated surfaces [4][5][6], etc.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Procedure to Estimate Lifetime of Water Drop with Graphite Inclusion under Intensive Vaporization with Explosive Breakup

2016

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Abstract.We developed an experimental setup equipped with tube furnace for continuous heating of heterogeneous drops at a constant temperature and high-speed camera to study characteristics of phase transitions at interfaces of these drops. Also, an experimental procedure was proposed to estimate time characteristics of processes occurring when heated heterogeneous drops in high-temperature environment. As an example, at temperature of heating of 1373 K, lifetime of 15 μl water drop with 1 mm solid inclusion made of natural graphite in high-temperature environment equals almost to 1 s. Experimental data also enabled to reveal minimum temperature at which intensive vaporization of 5 μl, 10 μl and 15 μl drops with inclusions in size of 2×2×2 mm proceeds with explosive breakup. This temperature equals to 803 ± 10 K depending on initial water volume in heterogeneous drops.

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“…A coalescência das bolhas é necessária para a formação de um estável filme de vapor. Entretanto quando sais são adicionados na água há uma mudança físico-química que diminui a coalescência de bolhas (Hsu et.al., 2015). Craig et.al.…”

Section: Temperatura E Agitação Do Meio De Resfriamentounclassified

“…Craig et.al. (1993) (Hsu et.al., 2015). Em resumo a existência de cargas elétricas de mesmo sinal entre as bolhas cria uma força eletrostática repulsiva, impedindo assim a sua coalescência suprimindo a estabilização do filme.…”

Section: Temperatura E Agitação Do Meio De Resfriamentounclassified

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Avaliação de meios de resfriamentos a base de soluções iônicas

Zordão¹

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The mechanical properties of steel components are influenced by the microstructure that is determined by the heat treatment cycle. In the quenching of the steel: water, oil, aqueous polymer solutions and aqueous salt solutions (brine) can be used as quenchants that exhibit different characteristic on cooling mechanisms. For example: when water is used as the cooling media, a stable vapor film is formed around the hot component resulting in non-uniformity of surface heat transfer during the cooling process which is often responsible for distortion and cracking. Salt addition can reduce or inhibit vapor film formation enhancing the uniformity of heat transfer during the cooling. This work will investigate the cooling performance of different ionic solutions (NaCl, NaOH, NaNO2, Na2SO4, NaHCO3) varying concentration, temperature (25, 35 and 45°C) and agitation of the quenchants (0, 500 and 800 rpm) and their use on quenching a low hardenable steel. The description of these medium and the influence of external factors were made using cooling curves, cooling rates, heat transfer coefficients and heat flux. Samples of SAE 1045 steel were quenched and evaluated by hardness measures and metallography. The use of ionic solutions, in general, has proved to be effective in to inhibit the vapor blanket, to increase heat extraction and keeping a high heat flux during the most part of the drop of the temperature that results in a homogeneous cooling able to avoid distortions. These solutions were abele to quench SAE 1045 steel.

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On the formation of vapor film during quenching in de-ionized water and elimination of film boiling during quenching in natural sea water

Cited by 74 publications

References 21 publications

Evaluación de la dureza y microestructura del acero 1045 templado en sustancias refrigerantes no tradicionales

Evaluación de la dureza y microestructura del acero 1045 templado en sustancias refrigerantes no tradicionales

An Experimental Procedure to Estimate Lifetime of Water Drop with Graphite Inclusion under Intensive Vaporization with Explosive Breakup

Avaliação de meios de resfriamentos a base de soluções iônicas

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