• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.327-331
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• 1997

As demand for various kinds and small lot products has been increasing, batch annealing has been appreciated for its small restiction for the opteration. The cold spot of the coil is very important in the BAF(Batch annealing furnace) annealing process. Because of the annealing cycle time in the BAF, annealing was decided on the cold spot of the coil. So, we tested the effect,variation of cold spot, for hydrogen contents of atmospheric gas at the annealing furnace. As a result of several investigations. We confirmed the following characteristics ; after the heating and soaking,the cold spot of coil moved to 1/3 of coil thickness in the NHx atmospheric gas, but the mid point of the coil thickness is the cold spot in the Ax or .H/sub2. atmospheric gas. Therefore, the use of hydrogen instead of nitrogen as the protective gas,combined with high convection in batch annealing furnaces, has shown that considerable increases in furnace output and material quality are attainable. Owing to the low density, high diffusion and reducing character of hydrogen, a better transfer resulting in uniform material temperatures and improved coil surfaces can be achieved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.629-632
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• 1995

The formability of an automobile body panel is very important. So, we performed an annealing condition change for the development of annealing condition with temperature, atmospheric gas and the annealing cycle. Formability was changed under the influenced of the mechanical properties of steel sheet for the automobile body panel. Therefore, ot os important in the BAF(Batch annealing furnace) annealing process. Because mechanical properties were decided on the heat treatment method of the coil. So, we tested the development of mechanical properties according to the heat treatment method at the annealing furnace using the Ax atmospheric gas and the HNx atmospheric gas. As a result of several investigations, we confirmed the following characteristics ; mechanical properties change under the influence of the annealing cycle and atmospheric gas.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.560-564
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• 1996

In recently, annealing process of cold rolled sheet tend to change to continuous annealing process for improving qualify, saving yield. In the meantime as demand for various kind and small lot of products has been increasing, batch annealing has been appreciated for its small restriction for the operation. So, we tested on the effect for a hydrogen contents of atmospheric gas at annealing furnace. As a result of several investigation. We confirmed for the following characteristics ; improved productivity, uniform heating, improved surface quality, saving energy. Therefore, the use of hydrogen instead of nitrogen as the protective gas, combined with high convection in batch annealing furnaces, has shown that considerable increases in furnace output and material quality are attainable. Owing to the low density, high diffusion and reducing character of hydrogen, a better transfer resulting in uniform material temperatures and improved coil surfaces can be achieved.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.2
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• pp.108-114
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• 1998

Development on the mechanical properties of steel sheet for the automobile body panel is very important in the BAF(Batch annealing furnace) annealing process. Because of the heat treatment method in the BAF, mechanical properties was decided on the heat treatment method of the coil. So, we tested on the development of mechanical properties according to heat treatment method at the annealing furnace using the Ax(H$_2$75%, $N_2$25%) atmospheric gas and the HNx(H$_2$4%, $N_2$96%) atmospheric gas. As a result of several investigations. We confirmed the following characteristics ; mechanical properties was changed under the influence of the annealing cycle, the heat treatment method and the atmospheric gas. And, elongation in the HNx BAF was better than the Ax BAF. Finally, most important thing in the BAF is using of proper annealing cycle in order to get a good quality.

• Journal of the Korean Institute of Gas
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• v.5 no.2 s.14
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• pp.9-13
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• 2001

A complete spectrum of risk assessment including qualitative and quantitative approaches were performed for the POSCO's Batch Annealing Furnace (BAF) gas systems. The purpose of BAF is to enhance the quality of steel by annealing it with either hydrogen/nitrogen mixture gas or pure hydrogen gas. Number of gas leak scenarios were identified to generate frequency of their occurrences. With the hypothetical accident scenarios given, fire/explosion impact studies were performed to estimate magnitude of significant consequences. Several different indices were also presented from which practical safety improvement action items could be established.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.2
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• pp.173-181
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• 1994

A Cold spot temperature control system for the batch annealing furnace has been estabilished in order to reduce energy consumption to improve productivity and stabilize the propertics of products. Therefore we confirmed a relation between annealing cycle time and atmospheric gas, variation of coil cold spot temperature with time during heating and actual temperature measurements at mid-width of each coil during heating and actual temperature measurements at mid-width of each coil during soaking. The results of the tempaeature variation effect on the batch annealing are as follows. 1) Heating time is reduced to one half with increasing atmospheric gas flow rate and changing of atmospheric gas component from HNx to Ax gas, and annealing cycle time is reduced to 2.7 times. 2) In case of short time healing, the slowest heating part is the center of B coil, in case of long time heating, the low temperature point moves from the center of coil to inside coil. And the temperature in this part is higher than other parts when cooling. When finished heating, the cold spot is located 1/3 of coil inside in case of HNx atmospheric gas. But center of coil in case of Ax atmospheric gas. 3) The outside of top coil is the highest temperature point when heating, which becomes the lowest temperature point when cooling. So, this point becomes high temperature zone at heating and low temperature zone at cooling, It has relation according to atmospheric gas component and flow rate. 4) Soaking time at batch annealing cycle determination is made a decision by the input coil width, and soaking time for quality homogenization of 1214mm width coil must be 2.5 hours longer than that of 914mm width coil for the same ciol weight. 5) Annealing cycle time with Ax atmospheric gas is extended 1 hour in of slow cooling during 5 hours in order to avoid rapid cooling.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.2
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• pp.159-167
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• 1996

The effect of atmospheric gas on the surface cleanliness in the batch annealing furnace(BAF) is presented. It is very important to improve the surface cleanliness to investigate the surface defects such as carbon contamination, smudge and yellow color phenomenon on the surface of steel sheet. In order to study the occurrence of surface defects of steel sheet, the annealing operations were carried out in the H2 BAF with 75% hydrogen and conventional BAF with 4% hydrogen. The hydrogen is important factor that affect the energy saving in the entire annealing cycle and the surface cleanliness. In the conventional BAF, it shows that to protect the yellow color phenomenon the proper finish temperature is $80^{\circ}C$ and in the smudge sample the oxidized thickness has the depth of $120{\AA}$.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.779-782
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• 1990

Recently batch type cold rolling processes have been replaced by continuous annealing type processes for cold rolled sheets of mild steel and high strength steel in order to obtain higher productivity, labor saving. In the continuous annealing line, it is very important to maintain the target steel strip temperature at the exit side of each furnace. The automation system of continuous annealing line is based on a hierachical composition. This paper shows how to preset the set value of furnace temperature control for the heating section in a continuous annealing line. Saying in other words, this paper presents the development of an adaptive control approach to control the exit strip temperature in the continuous annealing line. There are three parts in this approach; one is a process modelling and another is recursive parameter estimation and the other is a design of temperature controller.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.72-79
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• 1996

In a BAF(Batch Annealing Furnace), various studies have been pursued in order to reduce energy consumption rate to improve productivity and to stabilize the properties of products. The purpose of this study was to investigate the effects of both the atmospheric gas and convector plate shapes on the augmentation of heat transfer. The use of hydrogen instead of nitrogen as an atmospheric gas, combined with high convection in the BAF, has shown that considerable increases in furnace out put and significantly improved material quality are attainable. Because convector plate shapes make the atmosheric gas easily flow density, high diffusivity and reducing character of hydrogen, a better heat transfer rates resulting in uniform material temperature distribution and improved coil surface quality can be achieved. Also, it was found that the closed convector plate took more time for the annealing cycle time than the other plate type(open-type)by about ten hours.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.1
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• pp.114-122
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• 1994

A cold temperature control system for the BAF(batch annealing furnace) has been established in order to reduce energy consumption to imrpove productivity and stabilize the properties of products. Therefore we confirmed a relation between annealing cycle time and atmospheric gas, changing annealing cycle time according to BAF temperature with time during heating and actual temperature measurements cold spot during soaking. The results of the temperature variation effect on the batch annealing are as follows. 1) Cooling rate is increasing gradually with increasing atmospheric gas flow, but heating rate is hardly increasing without atmospheric gas component. Heating time is reduced to one half with increasing atmospheric gas flow rate and changing of atmospheric gas component from HNx to Ax gas and annealing cycle time is reduce to 2.7 times. 2) With enlarging the difference between furnace temperature and soaking temperature at the HNx BAF, heating time becomes short, but cooling time is indifferent. 3) If temperature difference of 300.deg. C in the temperature change of cold spot according to the annealing cycle control temperature, Hi-CON/H2BAF is interchanging at each other at 26hours, but HNxBAF at 50 hours. 4) Soaking time at batch annealing cycle determination is made a decision by the input coil width, and soaking time for quality homogenization of 1219 mm width coil must be 2.5 hours longer then that of 914mm width coil for the same coil weight at Hi-CON/H2BAF. But, it is necessary to make 2 hours longer at HNxBAF.