JPS629789A - Production for titanium clad steel by rolling - Google Patents

Abstract

PURPOSE:To improve the joining strength by forming a nickel plated layer after crashing a nickel particle on the surface of a titanium material, then by cladding with rolling the titanium material to a base steel plate at the specified temp. via the nickel plated layer. CONSTITUTION:The thin oxide film on the surface of a titanium material 23 is destroyed by crashing the nickel particle in 0.2-2mm mean grain diameter on the surface of at least one side of the titanium material 23. Thereafter a nickel plated layer 22 is immediately formed on the surface of the titanium material 23 by an electrolytic method or electroless method. The titanium material 23 and base steel plate 21 are joined at the interval of the nickel plated layer 22 and the periphery thereof is sealed by a carbon steel plate 24. The clad steel plate is obtd. with the cladding by rolling after heating at 600-850 deg.C of clad assembly stock 20. The joining strength is increased because of the joining of the titanium material 23 and base metal 21 being performed via the nickel plated layer 22 by removing the effect of the titanium oxide film.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing titanium clad steel by rolling, which has excellent interface bonding strength.

(Prior art) Titanium clad steel has traditionally been manufactured mainly by the explosion bonding method, and has been subject to significant limitations due to the explosion bonding method in terms of product dimensions, dimensional accuracy, productivity, and manufacturing costs. ing. Recently, an explosion rolling method has been devised in which rolling is performed after explosion bonding, and the dimensional range that can be manufactured and the dimensional accuracy are being improved. However, problems caused by the type of alloy phase produced and the occurrence of void defects remain. ing. Furthermore, recently, methods for manufacturing titanium clad steel sheets by rolling methods include methods using ultra-low carbon steel as the base material, methods using ultra-low carbon steel containing specific components that fix carbon in the steel, and methods using ultra-low carbon steel containing specific components that fix carbon in the steel.
A method using a steel plate on which a decarburized layer of μm or more is formed, a method in which a third metal plate is inserted or interposed between the titanium material and the steel base material as an intermediate layer, or a mating surface of the titanium plate and the base steel plate. Many methods have been devised, including a method to suppress the diffusion of metal elements by forming a thin oxide film on the surface of the metal.

On the other hand, from a metallurgical point of view, it is recognized that it is advantageous to provide a so-called insert material between the titanium material and the steel base material, and nickel, niobium, tantalum, etc. are used as such an insert material or an intermediate layer equivalent to the insert material. , some proposals have also been made to use .

For example, in the public shaft of JP-A-53-10347, titanium and nickel are explosively bonded in a three-layer cladding made of titanium/nickel/steel with nickel as an intermediate layer, and then 5
An explosion rolling method is disclosed in which rolling is performed at 50 to 850°C.

Furthermore, Japanese Patent Application Laid-open No. 58-41688 discloses that a clad steel of titanium and steel with niobium, tantalum, and their alloys interposed therein is manufactured by an explosion bonding method, and then this titanium clad steel is interposed therebetween. Another method is disclosed for cladding titanium and steel using appropriate means such as an explosion bonding method or a rolling method. However, all of these methods require high processing costs, such as using an explosive bonding method, and are not always sufficient to prevent the formation of fragile intermetallic compounds.

(Problems to be solved by the invention) As described above, all conventional titanium clad steel manufacturing methods suppress the formation of titanium carbide and intermetallic compound layers that are harmful to interfacial bonding properties, thereby improving the bond between titanium and steel materials. This is an attempt to improve bonding properties.

However, even if the formation of titanium carbide near the joint surface can be easily prevented, the formation of alloy layers and intermetallic compound layers caused by diffusion cannot be avoided.

One problem, then, is how to form an alloy layer or an intermetallic compound layer that is harmless to bonding properties, or rather improves them. As already mentioned, from a metallurgical point of view, “nickel,
Although the use of tantalum, niobium, etc. has been proposed, it has not yet been a sufficient solution in terms of specific means of application.

An object of the present invention is to provide a method for manufacturing titanium clad steel by rolling, which can be manufactured by simple means and has a high joint strength.

(Means for solving the problem) By the way, since titanium is a highly oxidizing metal, metal plating on its surface is not easy, and therefore it has been difficult to perform metal plating with good adhesion. .

When joining titanium and steel, the formation of titanium carbide and an alloy layer at the interface has a large effect on the joining property.

As already mentioned in the prior art, such titanium carbides can be formed by using ultra-low carbon steel, which is close to pure iron, as the base material, by inserting it into the interface between titanium and steel, or by applying it to the surface of the base steel. Although it can be removed relatively easily by forming a decarburized layer or further inserting a metal plate such as nickel, it is difficult to avoid the formation of an alloy layer. especially,
Due to the limited number of elements that can form a complete solid solution with titanium, and the fact that these metals are expensive, have poor workability, and lack practicality, in the production of titanium clad steel by rolling, an intermetallic compound layer is We must find ways to improve bonding by controlling the formation of this fragile intermetallic compound, keeping in mind the formation of intermetallic compounds.

In order to achieve the above-mentioned objectives, the inventors of this invention have made extensive studies and discovered that the cause of fracture in titanium clad steel joints is not the formation of the intermetallic compound layer itself, but the microscopic observation of the intermetallic compound layer. We found that the dispersion of oxides that form at the interface between titanium and the inserted metal plate makes the intermetallic compound even more brittle. The inventors have found that by tightly plating a titanium plate with an insert metal such as nickel, it is possible to produce a titanium crand steel plate by rolling.

That is, the inventors found that when using nickel as an insert metal plate, Ni5T is formed by diffusion alloying with titanium.
It is clarified that intermetallic compounds such as NiTi5 NiTig are formed and that destruction occurs mainly at the original bonding interface and Ni3Tt, and that this intermetallic compound layer is within an appropriate range as shown in Figure 1. I learned that the strength increases. Furthermore, this bonding strength greatly depends on the amount of oxygen at the fracture interface, as determined by Auger electron spectroscopy.
As shown in Figure 1, the smaller the ratio of the KLL peak of oxygen to the LMM peak of nickel in an Auger electron spectrometer, the better the bonding strength can be obtained even if a thicker intermetallic compound layer is formed. I found out that it can be done.

From these research results, we have found that preventing oxidation at the interface between the titanium plate and the inserted metal plate, in other words, removing oxygen, greatly contributes to improving the bonding hardness. however,
The air at the interface between the titanium plate, the inserted metal plate, and the base steel can be extracted with a vacuum pump after welding and assembly, but in actual production lines, the vacuum level that can be reached is sufficient to improve the joint strength. It is not easy to increase Therefore, after applying nickel plating with good adhesion to the surface of the titanium plate in advance, and then aligning it so that the nickel plating surface meets the steel containing 0.10% or more carbon, 85
The present invention was completed by discovering that rolling titanium clad steel with good bondability can be produced by rolling at a temperature range of 0°C to 600°C.

In view of the current situation, this invention provides a method of plating nickel on the surface of titanium material with good adhesion in order to manufacture rolled titanium clad steel, which has a bondability far superior to that of conventional rolled titanium clad steel. The gist of this method is to collide nickel particles onto the surface of a titanium material, destroy the thin oxide film formed on the surface, and destroy the nickel. After partially embedding the particles in the surface of the titanium material, a nickel plating layer is formed, and then the titanium material is heated to 600 to 850°C and rolled and crimped to a base steel plate via the nickel plating layer. , a method for producing titanium clad steel by rolling.

According to a preferred embodiment of the present invention, the thin oxide film on one surface of titanium has an average particle size of 0.2 ml to 21 ml.
The nickel plating layer was destroyed by the so-called shot blasting method in which 1II11 nickel particles were collided with each other, and the nickel particles were partially embedded in the titanium surface. Form a layer with a thickness of 10 μm or more, or immediately add 80 g of N15 to 11 parts of water.
O, and a solution containing a trace amount of sodium succinate as a stabilizer to an aqueous solution containing 25 g of sodium hypophosphite.
Apply by heating to a temperature of 5°C to form an electroless nickel plating layer of 10 μm or more, and then combine this nickel-plated titanium plate with the nickel plating layer and steel containing 0.10% or more carbon. It has excellent bonding properties and is made by sealing the periphery by welding, heating it to a temperature range of 850°C to 600°C and rolling it.
Furthermore, this is a method for manufacturing titanium crand steel by rolling, which eliminates degassing after welding and assembly.

As described above, according to the present invention, the presence of the nickel plating layer eliminates the influence of oxygen and increases the bonding strength, and the surface to be treated is cleaned by shot blasting with nickel particles prior to nickel plating. Not only that, by embedding some of the particles into the surface, the strength of the bond with the nickel plating layer that will be applied later is further improved by the mechanical bonding effect.Of course,
As long as such a synergistic improvement in bonding strength is achieved, there are many possible means for providing this nickel plating layer, including shot blasting of nickel particles, but the present invention provides One feature is that vacuuming is omitted prior to the rolling process, so any material with good adhesion may be used. For example, the plating layer may be provided by a thermal spray nickel coating method or the like.

(Function) As is already well known, titanium is a highly oxidizing metal and easily forms an oxide film when it comes into contact with air. Therefore, in order to perform nickel plating on this, a nickel plating layer with good adhesion cannot be formed unless a so-called surface activation treatment is performed to destroy and remove this oxide film as a pretreatment. In this regard, according to the present invention, the surface oxide film is destroyed by the so-called shot blasting method in which nickel particles having an I-average particle size of 0.2a+m to 21111 collide with the titanium surface, and the nickel particles are partially exposed to the titanium surface. This allows for nickel plating with good adhesion. For this purpose, it is preferable that the oxide film cannot be completely destroyed unless the average particle size of the nickel particles is 0°21 or more, and that if it exceeds 2+1111, the nickel particles will be buried in the titanium surface. The area ratio decreases, making it impossible to perform nickel plating with good adhesion. The shot blasting operation itself may be generally well known. Generally, approximately 100% of the surface oxide film is removed by treatment for 5 seconds to 10 minutes, resulting in a clean surface.

The clean surface thus prepared is immediately covered with a nickel plating layer. Nickel plating methods can be broadly classified into electroplating and electroless plating, but other methods may be used. Wand bath used for electrolytic nickel plating (NiSOn 240g/Il, Ni
C1t 7g/j! , boric acid 30g80 It is generally well known that when plating on a titanium surface, the current density is 2^/dll! If it is not above, the workability will be poor, and if IOA/d is more than 2, it will not be possible to form a dense plating layer. In addition, electroless plating solution (NiSOJOg/12, sodium hypophosphite 25g
/It, mW of sodium succinate) is also a well-known plating solution. Nickel plating itself is well known and it is sufficient to treat it accordingly.

This type of nickel plating is performed to prevent oxidation of the titanium-nickel interface during welding assembly and rolling heating, and to suppress the formation of titanium carbides that are harmful to bonding properties due to carbon in the steel diffusing into the titanium. For this purpose, it is sufficient if the rolling heating temperature range of the present invention is 10μ1 or more.

Next, as described above, the nickel-plated titanium material and the base steel plate are brought together with the nickel-plated side in between,
It is surrounded by a mild steel plate and sealed by welding. FIG. 2 is a schematic cross-sectional view of this clad assembly material 20, in which nickel plating N22 is placed on a carbon steel base material 21, and this nickel plating layer 22 is provided on a titanium material 23. It is something that The entire titanium material 23 is surrounded by carbon w424 of mild steel, and its periphery 26 is welded and sealed to the carbon steel base material 21.

The clad assembly materials thus welded and assembled are tightly joined by rolling, but in that case, the heating temperature for rolling is
If the temperature exceeds 850°C, the structure of the titanium material will transform into a beta phase and the formation of intermetallic compounds will become significant, which is harmful.

Further, if the temperature is lower than 600°C, the bondability between the nickel and the steel deteriorates significantly, making it impossible to obtain a predetermined bonding strength.

The reason why a steel containing 0.10% or more of carbon was selected as the base material in preferred embodiment B of this invention is to prevent the base material strength from being low as a clad steel.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 A titanium plate with a thickness of 10m+w was plated with nickel under the conditions shown in Table 1, and a plating layer of 15μl (11) or 150μ- nickel foil was inserted, and assembled by welding and sealing as shown in Figure 2. Ta. The shot blasting conditions are a pressure of 5kgf/Cl11! , spraying amount 1000g
/1Ilin, time was 2 minutes. 0 for carbon steel
A plate containing 15% C was used and the plate thickness was 90 mm. This was rolled to a thickness of 201111 under the same rolling heating conditions shown in Table 1, either by vacuum degassing with the conduit attached at the time of welding sealing, or without degassing, and its bondability was evaluated by a shear tensile test. . The results are shown in Table 1, with a shear strength of 15 kg/ms" or less being judged as failure, and a shearing strength of 15 kg/ms" or less being judged as good.

Table 1 (Note) Electroplating: Current density fermentation Electroless plating:

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the results of Auger electron spectroscopy and bonding strength; and FIG. 2 is a schematic cross-sectional view of the clad assembly material.

Claims (1)

[Claims] In a method for manufacturing titanium clad steel by rolling, nickel particles are collided with the surface of a titanium material to destroy a thin oxide film formed on the surface and partially embed the nickel particles in the surface of the titanium material. A method for manufacturing titanium clad steel by rolling, in which a nickel plating layer is then formed, and then the titanium material is heated to 600 to 850°C and rolled and crimped to a base steel plate through the nickel plating layer.