JPS5848655A - Preventing method for dew condensation in heat treatment of aluminum slab - Google Patents

Abstract

PURPOSE:To prevent dew condensation on the surface of an Al slab by coating the slab with a liq. which is not burned off by heating up to about 100 deg.C and is burned off by heating to >= about 100 deg.C and by heating the coated slab in a heating furnace. CONSTITUTION:When an Al slab is planed, charged into a heating furnace, and homogenized or soaked before carrying out hot rolling, the slab is coated with a liq. which is not burned off by heating up to about 100 deg.C in the furnace and is burned off by heating to >= about 100 deg.C. The liq. is a soln. of acrylic resin or epoxy resin, rust preventing oil, silicone oil, glycerol or the like. Thus, even if the slab is heated to about 500-600 deg.C, the deterioration of the quality due to dew condensation can be prevented because the state with the formed coat on the planed surface of the slab is maintained until the slab reaches a temp. at which dew condensation is caused.

Description

DETAILED DESCRIPTION OF THE INVENTION A method for preventing dew condensation from forming on the surface of an aluminum slab, specifically, when the aluminum slab is charged into a heating furnace and subjected to homogenization or soaking treatment before being hot rolled. This invention relates to a method for preventing dew condensation.

Conventionally, aluminum slabs are charged into a heating furnace, uniformly heated, and then hot rolled. However, when an aluminum slab is directly heated with combustion gas from the lower part of the furnace, dew condensation may form on the side surfaces during the process of heating the aluminum slab to about 100C. Particularly, dew condensation occurs in the winter when the actual temperature of the aluminum slab is low. This condensation has the characteristic of flowing from the upper part of the aluminum slab, where the temperature rise is delayed, down the side surface of the aluminum slab. present,
In addition, since the oxide film is formed locally, it may remain on the plate surface after rolling or cause scratch-like defects.
The quality was not good.

The present invention is a method for preventing dew condensation during heat treatment of an aluminum slab in which dew condensation does not form on the side surface of an aluminum slab in a heating furnace, and the aluminum slab does not burn out until it is heated to about 100C, and ,
A liquid that is burnt out when the aluminum slab is heated to 100C or higher, such as an acrylic resin solution, is applied to the surface of the aluminum slab, and then the aluminum slab is charged into a heating furnace and heated. It is characterized by this.

The present invention will be explained in detail below.

During hot rolling of an aluminum slab, the surface of the aluminum slab is milled, and when it is charged into a heating furnace for homogenization or soaking treatment, the amount of surface milling on the aluminum slab is equal to the amount of heat applied to the slab. A liquid is applied that does not burn out until it is heated to about 100C in a furnace and is burned away when heated above about 100C. Examples of this liquid include solutions of acrylic resins, epoxy resins, etc., chiseling oil, silicone oil, glycerin, and the like. However, if the aluminum slab is charged into a heating furnace and the liquid does not burn out until it is heated to about 100C, and if it is a liquid that burns out when it is heated above about 100C, then the example Not limited. Aluminum slab heated to approximately 100C in a heating furnace
The reason for using a liquid that does not burn out until the aluminum slab is heated is that in the process where the actual temperature of the aluminum slab rises to approximately 100C, moisture in the heating combustion gas condenses on the surface of the aluminum slab. Such a liquid is applied to the surface of the aluminum slab by spraying or other conventional application means, and then the aluminum slab is charged into a heating furnace. At this time, the applied liquid may be charged after drying, or may be charged immediately after application. In either case, a coating is formed on the surface of the aluminum slab by the applied liquid. As described above, after the aluminum slab is charged into the heating furnace, the aluminum slab is heated to about 500 to 6000 °C for a predetermined period of time to perform homogenization or soaking treatment, as in the conventional method.

When an aluminum slab is heat-treated in a heating furnace, dew condensation occurs on the surface of the aluminum slab when the amount of surface removal increases to approximately 10 oc. In the present invention, a liquid that does not burn out until the aluminum slab is heated to approximately 1 ooc is coated on the surface of the aluminum slab. is currently being formed. Therefore, even if dew condensation occurs temporarily on the surface of the aluminum slab, it is protected by the coating, so no trace of dew condensation occurs. Further, when the aluminum slab is heated and its temperature reaches approximately 1oOC or higher, the liquid applied to the aluminum slab is burned away, so that it does not remain during hot rolling. Therefore, the product is beautiful without deterioration or discoloration due to oxidation of dew condensation traces.

Examples will be described below, but the present invention is not limited to the following examples.

Example 1.゛Acrylic resin paint manufactured by Sakuramiya Chemical Co., Ltd. (product number 5K81) was applied to the surface cutting amount of the AA5182 aluminum alloy slab.
00) and the same company's thinner (B thinner) at a ratio of 0 (vo 1%) was applied, the solution was dried, and the undried slab was placed in a heating furnace. It was loaded into

For comparison, an aluminum alloy slab not coated with the solution was also charged at the same time and heat treated for 10 hours at an ambient temperature of 530C and an actual slab temperature of 500C.After that, the aluminum alloy slab was taken out of the furnace. The presence or absence of condensation was observed.

As a result, the amount of face removal of the slab coated with the solution was determined by drying,
There was no trace of dew condensation on any of the undried surfaces, and the applied solution had been completely burnt off. on the other hand,
Local discoloration and the formation of an oxide film, which are characteristics of dew condensation marks, were observed in the amount of surface removal on the slabs that were not coated with the solution.

Example 2 Epoxy resin paint manufactured by Sakuranomiya Chemical Co., Ltd. (product number J-
Two types of solutions were prepared in which 26-9-A) and triol were mixed at a ratio of 1=2.1:8 (701%), and Example 1.
Each solution was applied separately to the same amount of surface cut on the aluminum alloy slab as in the above, and both solutions were charged into a heating furnace while the solutions were not dried.

For comparison, a slab to which no solution was applied was also charged at the same time as in Example 1. The same heat treatment as above was carried out, and after that, the samples were taken out of the oven and observed for the presence or absence of dew condensation.

As a result, epoxy fMMll? There was no trace of dew condensation on the faceted surface of the slab to which the system solution was applied. Also, among the solutions that had been applied, the mixed solution in Part 8 was completely burnt off, but the mixed solution in Part 2 was slightly coated.
There were traces left. However, it was not a problem. On the other hand, traces of condensation similar to those in Example 1 were observed on the faceted surface of the slab to which the solution was not applied.

From the above results, it was found that when the actual temperature of the aluminum slab charged into the heating furnace reached 5oOC, the acrylic resin and epoxy resin in particular were completely burnt out. It was also found that the resin was not burnt out and remained in a film state until the actual temperature reached 100C. It is also clear that the smaller the mixing ratio of these resins, the better.

Claims (1)

[Claims] When heat-treating an aluminum slab before hot rolling, the side surface of the aluminum slab is not burnt out until the aluminum slab is heated to about 100C in a heating furnace, and when it is heated to about 100C or more. 1. A method for preventing dew condensation in heat treatment of an aluminum slab, which comprises applying a liquid that burns out, and then placing the aluminum slab in a heating furnace and heating it.