JPH0452030A - Method for working titanium clad steel sheet - Google Patents

Abstract

PURPOSE:To make the working for complicated shape possible by subjecting the clad steel sheet of laminated material of Ti to working in the range of specific temperature. CONSTITUTION:The Ti clad steel sheet made with the steel as base material and the Ti as the material to be laminated is heated >=50 deg.C, <=400 deg.C, and worked. Therefore, the working limit for the Ti clad steel sheet is enlarged, and the working for the vessel with bending and drawing is made possible. On this result, the Ti clad steel sheet can be applied to the vessel of complicated shape and the improvement of its corrosion resistance, the improvement of its life, the abolition of maintenance of periodical painting, etc., and the generation of healthful and sanitary effect due to nothing of surface stain, etc., is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application) The present invention relates to a method for processing a titanium clad steel plate.

Titanium clad steel sheets have been used mainly for thick plate applications such as chemical equipment, taking advantage of titanium's excellent corrosion resistance.

However, in the processing of thick plates, processing by plastic deformation involves a very light bending of one degree, and most of the processing involves welding with a groove, so there has been no demand for improved workability. However, the present inventors have recently developed a technique for manufacturing very inexpensive titanium clad thin steel sheets, as will be described later. As a result, there has been an increasing desire to use titanium clad thin steel sheets not only as flat sheets, but also for thin sheet applications that require complex plastic working. The present invention was made in response to these demands, and relates to a processing method that expands the processing limits of titanium clad thin steel sheets.

(Conventional technology) The production of titanium clad steel requires brittle F at the interface between titanium and steel.
When layers such as e-Ti intermetallic compounds and TiC are formed at the interface! IJ! Because of this, the cast-in method using molten steel is not applicable, but joining using solid phase is used instead.

In particular, the explosive bonding method is currently widely used because it does not use an intermediate bonding material and is highly reliable in terms of bonding strength. The method of rolling welding is used in some areas because it has high productivity, allows for relatively flexible plate thickness, and can be applied to production processes for steel, etc., and can be manufactured at a lower cost than the explosion bonding method. .

However, in the pressure welding method, there is a very high possibility that a brittle layer such as an intermetallic compound will be formed at the bonding interface, and the reliability of the bonding strength is actually inferior to that of the explosive bonding method. Particularly in the case of hot welding, this risk is significantly increased due to the increased diffusion rate. As a method to increase bonding strength by suppressing the formation of a brittle intermediate layer at the interface, JP-A-Sho δ2-5
No. 783 includes limitations on hot rolling heating conditions, and examples include JP-A-55-48468 and JP-A-57-10958.
No. 8, JP-A No. 57-112985 and JP-A No. 5
Publication No. 7-192256 discloses a method in which a plate or foil of pure iron, nickel, copper, etc. is sandwiched at the crut interface as an intermediate welding material. However, even with these methods,
If oxides form at the interface, bonding becomes impossible, so as a general rule, it is essential to maintain the surface in a vacuum before bonding.

As mentioned above, titanium clad steel plates require special equipment and large costs to manufacture, so only thick plates with a large cost advantage of reducing T1 thickness are manufactured, and are mainly used for chemical equipment etc. It was only used for special purposes. In such thick plate applications, the only processing that utilizes plastic working is light bending with a large radius of curvature (for example, "Titanium Zirconium J").
Vol, 35 No, 1 January 1986 p, 23-3
1) Strict processing such as close facing and press processing, which is done with thin plates, was not required. In other words, until now there has been no thin steel plate for titanium clad steel, and the processing of manufactured thick titanium clad steel plates into components is mostly done by welding with a bevel, so the workability has deteriorated. There was no demand for the development of better titanium clad steel sheets or for improvements in processing methods.

In other words, until now there was no titanium clad thin steel sheet that could be used for low-cost, demanding applications such as thin sheets.
No improvements were made to the processing method itself, and no processing method for increasing the processing limit was disclosed.

(Problems to be Solved by the Invention) In response to this, the present inventors have invented a method for manufacturing titanium clad thin steel sheets that actively utilizes intermetallic compounds of Ti and Cu and eliminates the need for a vacuum (Unexamined Japanese Patent Publication No. 1-122677). As a result, we have developed a titanium-clad thin steel plate that is significantly lower in cost than conventional thick titanium-clad steel plates. For this reason, there has been a growing movement to take advantage of Ti's overwhelmingly excellent corrosion resistance and apply it to building materials, automobile parts, home appliance parts, etc. When applied to these uses, it is essential that titanium clad steel sheets have the same workability as thin steel sheets. Against this background, there have been increasing demands for improvements in the workability of titanium clad thin steel sheets, as well as improvements in processing methods.

Incidentally, the actual situation is that titanium clad thin steel sheets are inferior in workability compared to steel as a base material and Ti thin sheets as laminated materials. One of the reasons for this is that when titanium clad steel sheets are processed, in addition to the normal processing damage of thin sheets, such as cracking (in the case of titanium clad steel sheets, this appears as a crack in the Ti) and ductile fracture, damage due to interfacial peeling occurs. appear.

The present invention focuses on damage caused by this interfacial peeling and provides a processing method that can avoid it.

(Means for solving the problem) A titanium clad thin steel plate with a total thickness of 5 mm and a crat ratio of 10% was produced in the atmosphere by actively utilizing the intermetallic compound of Ti and Cu shown in the above-mentioned Japanese Patent Application Laid-Open No. 1-122677. Manufactured. Using this titanium clad steel plate, a bending test was conducted with the Ti surface as the outer surface.

In the external bending test with Ti on the outside, when the cross sections of the test pieces were observed at various bending angles, it was observed that cracks occurred immediately below the Ti layer prior to the breakage of the Ti on the surface. In other words, it has been found that processing damage to titanium clad steel sheets is dominated by the workability of the interface directly under the Ti layer. By the way, a so-called hard layer of intermetallic compounds and β-Ti exists, albeit slightly, at the interface between Ti and the steel directly below it or the metal of the intermediate welding material. It is thought that the destruction of the interface that occurs prior to the processing damage that appears on the surface originates from this interfacial hard layer. Therefore, it has been found that improving the workability, particularly the ductility, of these hard layers will improve the workability of titanium clad steel sheets. Since the workability of intermetallic compounds and the like is greatly influenced by the working temperature, the present invention aims to increase the working temperature of the titanium clad steel sheet.

Figure 1 shows the effect of processing temperature on bendability. In the figure, the X mark indicates the occurrence of a tear on the Ti surface, the ○ mark indicates no breakage, and the mu mark indicates peeling at the edge portion.

As is clear from the figure, the higher the bending temperature, the better bending was possible with a smaller bending radius. Generally, metals have good ductility at high temperatures. Therefore, the processability is better at high temperatures, and the processing limit is usually narrower at lower temperatures than at higher temperatures. This trend was also enhanced with titanium clad steel plates.

Furthermore, from the results shown in Figure 1, when the processing temperature is less than 50℃,
First, it was found that edge damage occurred and reduced bendability, but when the value exceeded 50, cracks on the Ti surface corresponding to cracks caused by normal bending occurred, reaching the bending limit. In other words, it was found that titanium clad steel sheets can only be processed within a much narrower range than the workability limits of the individual metals of the base material and composite materials when the processing temperature is around room temperature below 50°C. It is. In other words, when processing titanium clad steel sheets, at temperatures around room temperature, the workability of the interface between the base material and the composite material dominates the overall workability, or at temperatures above 50°C, the individual metals of the base material or the composite material This makes it possible to process up to the limit of the workability that the metal alone has.

The present invention has been made based on this knowledge. That is, (1) A method for processing a titanium clad steel plate, which comprises heating a titanium clad steel plate using Ti as a laminated material and steel as a base material to a temperature of 50° C. or higher and 400° C. or lower.

invented. Furthermore, the same effect can be obtained by heating the bending die used for bending, or by heating the die and punch in the case of pressing. When bending the titanium clad steel plate used as the base material, the bending die was
A method for bending a titanium clad steel plate, which is characterized by processing by heating to a temperature below ℃.

(3) A titanium clad steel plate characterized in that when pressing a titanium clad steel plate using Ti as a laminating material and steel as a base material, the press die and punch are heated to a temperature of 50°C or more and 400'C or less. Pressing method.

invented.

Next, the limiting conditions of the present invention will be shown.

If the processing temperature is less than 50° C., peeling damage will occur at the interface, and processing can only be performed within a much narrower range than the workability limit of the metals of the laminated material and the base material, so the lower limit was set. Moreover, if it exceeds 400 t, not only will oxidation progress on the steel side, but also oxygen will enter into the Ti, resulting in deterioration of workability, so the upper limit was set.

(Function) In the present invention, by setting the processing temperature higher than room temperature, the workability of the interface between the base material and the composite material could be improved to the level of workability of the base material or the composite material alone. the result,
In room-temperature processing, processing damage to the interface caused by the shear stress of the interface member that occurs in advance is suppressed, and processing of the base material or mating material to near the processing limit is now possible.

Furthermore, by processing at a processing temperature higher than room temperature,
It is possible to perform more severe processing than normal temperature processing on the same basis as general metals.

In the present invention, these effects combine to expand the processing limits of titanium clad steel sheets, making it possible to process them into objects by bending and drawing.

(Example) Based on the method disclosed in the above-mentioned Japanese Unexamined Patent Publication No. 122677, titanium cladding with a total thickness of 5 mm and a cladding ratio of 10% was produced in the atmosphere by actively utilizing intermetallic compounds of Ti and Cu. A thin steel plate was manufactured. Using this titanium clad steel plate, an outer bending test was conducted with the Ti surface as the outer surface. The results are shown in Table 1.

In the heating bending method of the present invention, the bending radius is 180° with a bending radius of 5 mm.
The bending is completed, but the bending radius is 10mm when bent at room temperature.
18° bending was also impossible because peeling (interface displacement) occurred at the interface.

In addition, a total thickness of 1 mm and a crut ratio of 1 were manufactured using the same method.
Using a 0% titanium clad steel plate, a cylindrical drawing with a tip of 40R was performed with the Ti surface as the outer surface.

At this time, the mold and punch were heated to various temperatures. The results are shown in Table 2. In the method of the present invention, the drawing process was completed without tearing the Ti surface, or in the comparison room temperature process.
A tear occurred on the Ti surface at one corner, and the Ti peeled off from there.

Table 2 RT: Room temperature (20° C.) (Effects of the invention) The method of the present invention made it possible to process a titanium clad steel plate with excellent corrosion resistance into a complex shape. As a result, it has become possible to apply titanium clad steel to vessels with complex shapes, which has immeasurable resource and industrial benefits, such as significantly improving the corrosion resistance and extending the lifespan of those vessels. Furthermore, in applications where regular maintenance such as painting was indispensable in the past, it is virtually unnecessary, and a significant economic effect can be expected from this aspect as well. In addition, it not only eliminates surface stains but also eliminates health and hygiene concerns associated with rusting, which can also provide financial benefits to the company.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the influence of bending temperature on the bendability of a titanium clad steel plate. 4 other people Bending temperature ['C]

Claims (1)

[Claims] 1. A method for processing a titanium clad steel plate, which comprises processing a titanium clad steel plate using Ti as a laminated material and steel as a base material by heating it to a temperature of 50°C or more and 400°C or less. 2. A method for bending a titanium clad steel plate, which comprises heating a bending die to a temperature of 50°C or more and 400°C or less when bending a titanium clad steel plate using Ti as a laminated material and steel as a base material. 3. When pressing a titanium clad steel plate with Ti as the laminating material and steel as the base material, the press die and punch were
A method for processing a titanium clad steel sheet, characterized by processing it by heating to a temperature of 0°C or higher and 400°C or lower.