JPS61253400A - Method for descaling austenitic stainless steel - Google Patents

Abstract

PURPOSE:To considerably shorten the time required to pickle a rolled and annealed austenitic stainless steel and to reduce the cost by introducing the steel into an electrolytic pickling tank and carrying out electrolytic pickling at a specified current density or above. CONSTITUTION:A rolled and annealed austenitic stainless steel is introduced into an electrolytic pickling tank and descaled by electrolytic pickling at >=50A/dm<2> current density. By this method, the time required to pickle the steel is considerably shortened to about 10sec.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thin steel plate made of austenitic stainless steel (
rolling, annealing, and
The present invention relates to a method for descaling austenitic stainless steel in which scale generated during annealing is removed in a pickling process.

[Prior art] As a method for removing scale generated on the surface of a steel plate,
There are alkali salt treatment methods, neutral salt electrolysis methods, etc. The alkali salt treatment method will be explained with reference to FIG. 4. Figure 4 is a diagram showing the outline of the alkali salt treatment method.
Reference numeral 101 in the figure is a salt bath, and the annealed stainless steel thin plate 102 is first introduced into this salt bath 101.

Thereafter, heating furnace 103, washing tank 104, electrolytic pickling tank 1
05, washing tank 106, immersion tank 107 and washing tank 108
It passes through and is processed. Note that the reference numeral 109 in the figure is an electrode installed in the electrolytic pickling tank 105.

According to the above configuration, the stainless steel thin plate 102 is first introduced into the salt bath 101 filled with molten alkali salt (for example, sodium nitrate or caustic soda), where the scale attached to the surface reacts with the salt. Thereafter, it is heated in a heating furnace 103 and washed in a washing tank 104.

After this water washing step, the material passes between the electrodes 109 of the electrolytic pickling tank 105 and is subjected to electrolytic pickling. In this electrolytic pickling, the current density is about 5 to 10 A/dmZ. After the stainless steel thin plate 102 is electrolytically pickled, it is placed in a washing tank '106 and an immersion tank 10.
7 and a washing tank 108.

[Problems to be Solved by the Invention] According to the above configuration, the amount of alkaline salt consumed in the salt bath 101 is large, and there are problems with electricity! There are problems in that electrolytic pickling in the pickling tank 105 requires a long time and that the electrolytic pickling tank 105 becomes large.

The present invention has been made based on the above points, and its purpose is to effectively reduce the amount of alkali salt consumed in the salt bath, shorten the pickling time, and downsize the electrolytic pickling tank. The purpose of the present invention is to provide a method for descaling austenitic stainless steel.

[Means for Solving the Problems] That is, the method for descaling austenitic stainless steel according to the present invention is to introduce austenitic stainless steel that has been rolled and annealed into an electrolytic pickling tank and to electrolytically pickle the austenitic stainless steel. In the stainless steel descaling method, the electrolytic pickling in the electrolytic pickling tank is carried out at a current density of 50 A.
This feature is characterized in that it is performed at a speed of /dm2 or higher.

[Function] In other words, focusing on the fact that when the current density in the electrolytic pickling tank is set to 50 A/dm2 or more, the electrolytic pickling time is significantly shortened, the electrolytic pickling time is shortened and the electrolytic pickling tank is The aim is to reduce the size and reduce the burden on processing before the electrolytic pickling tank.

[Effects of the invention] Therefore, the time required for electrolytic pickling can be significantly shortened, the electrolytic pickling tank can be made smaller, and the burden of processing before the electrolytic pickling tank can be significantly reduced, and costs can be reduced. It is extremely effective in reducing

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 is a diagram showing a schematic configuration of a descaling apparatus according to this embodiment. Reference numeral 1 in the figure is a salt bath, and the annealed stainless steel thin plate 2 is first introduced into this salt bath 1. Thereafter, heating furnace 3, washing tank 4, electrolytic pickling tank 5
, a washing tank 6, an immersion tank 7, and a washing tank 8 to be processed. Note that the reference numeral 9 in the figure is an electrode installed in the electrolytic pickling tank 5.

Further, in this embodiment, the current density in the electric Wi pickling tank 5 is set to 50 A/dm2 or more. The background will be explained below with reference to FIG.

FIG. 2 is a diagram showing the relationship between the current density on the horizontal axis and the electrolytic pickling time on the vertical axis. As is clear from FIG. 2, when the current density is 50 A/dm2 or more, the pickling time is significantly shortened to approximately 10 seconds. This is a significant reduction in time compared to the conventional case where the current density was about 1 OA/dm2, which required about 10 to 20 minutes. In this way, this embodiment attempts to shorten the pickling time by setting the current density in the electrolytic pickling tank 5 to 50 A/drn2.

According to this embodiment, the following effects can be achieved.

(1) First, E'b allows the pickling time in the electrolytic pickling tank 5 to be significantly shortened, thereby making it possible to shorten the length of the electrolytic pickling tank 5 as shown in FIG. In addition, even if the line speed increases, a small electrolytic pickling tank 5 is sufficient.

(2) Also, since the descaling effect of electrolytic pickling is large, the burden of alkaline salt treatment at the stage before electrolytic pickling tank 5 is reduced, and as a result, the treatment steps before salt bath 1 and washing tank 5 can be omitted. It also becomes possible.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams showing one embodiment of the present invention.
The figure shows the schematic configuration of the descaling device, Figure 2 shows the relationship between current density and electrolytic pickling time, and Figure 3 shows a schematic diagram of the descaling device in which the treatment steps before the electrolytic pickling tank are omitted. FIG. 4 is a diagram showing a schematic structure of a conventional descaling device. 1...Salt bath, 2...Austenitic stainless steel thin plate, 3...Heating furnace, 4, 6.8...Washing tank, 5
... Electrolytic pickling tank, 7... Immersion tank, 9... Electrode. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 3 Figure 41yJ

Claims (1)

[Claims] In a descaling method for austenitic stainless steel in which rolled and annealed austenitic stainless steel is introduced into an electrolytic pickling tank and electrolytically pickled, the electrolytic pickling in the electrolytic pickling tank is carried out at a current density of 50 A/dm^2. A method for descaling austenitic stainless steel characterized by performing the above steps.