CN1039976C

CN1039976C - Process for manufacturing rolled articles of titanium material

Info

Publication number: CN1039976C
Application number: CN 92101037
Authority: CN
Inventors: 吉野明; 仙北谷春男; 田原正昭
Original assignee: Daido Sanso Co Ltd
Current assignee: Air Water Inc
Priority date: 1992-02-07
Filing date: 1992-02-07
Publication date: 1998-09-30
Anticipated expiration: 2007-02-07
Also published as: CN1075105A

Abstract

The present invention relates to a method for manufacturing rolled articles of a titanium material, which comprises the following steps: making a heated titanium material contact gas containing fluorine or the gas of fluoride; generating a fluoride layer on the surface of the titanium material; removing the fluoride layer generated on the surface of the titanium material before the titanium material is rolled; rolling the titanium material to make the rolled articles. By the steps, passive coating, such as an oxide layer on the surface of the titanium material, is converted into the fluoride layer. The fluoride layer is used for protecting the surface of the titanium material. Thus, even if the formation and the removal of the fluoride layer have a time interval, the fluoride layer formed on the surface of the titanium material protects the surface of the titanium material in a favorable condition, so an oxide layer is prevented from forming on the surface of the titanium material again.

Description

Method for manufacturing rolled article of titanium material

The invention relates to a method for manufacturing a rolled product of titanium material.

When titanium reaches high temperatures (above about 600 c), the titanium reacts with oxygen in the air to form a ten mu thick oxide layer or film on or in its surface layer. Therefore, during the hot rolling of titanium, an oxide film is formed on the surface of the red-hot titanium. Since titanium oxide has poor ductility, titanium is easily cracked. Generally, it is necessary to appropriately adjust the rolling speed or the rolling temperature to each kind and quality or the characteristics of the material to prevent cracking thereof.

However, it is very difficult to adjust the rolling speed and the rolling temperature to be suitable for each kind and quality of material, and it is practically impossible to eliminate cracking and the like.

Meanwhile, as a method of cold-rolling a titanium plate, japanese laid-open publication No. 33005/87 proposes a method comprising temporarily forming a titanium fluoride layer on the surface of a titanium plate before cold-rolling the titanium plate. After rolling, the titanium fluoride layer on the surface of the titanium plate is removed, which causes a problem that the titanium fluoride layer on the surface of the titanium plate cracks.

It is therefore an object of the present invention to provide a method for manufacturing rolled products of titanium material. The method prevents the occurrence of cracks or the like on the surface of the titanium material in rolling.

To achieve the above object, a method for manufacturing a rolled product of titanium material comprises the steps of: a titanium material is contacted with an inert gas containing fluorine or fluoride under heating to form a fluoride layer on the surface of the titanium material, and then the titanium material is rolled to produce a rolled product, wherein the concentration of the gas containing fluorine or fluoride in the inert gas is set to be 1000 to 100000ppm, and hydrogen gas is sprayed onto the surface of the titanium material immediately before the start of rolling to reduce and remove the fluoride layer formed on the surface of the titanium material.

In detail, in the method for manufacturing a rolled product of a titanium material according to the present invention, the titanium material is contacted with a gas containing fluorine or fluoride under heating before rolling the titanium material, for example, by passing the titanium material through an atmosphere of an inert gas containing 1000 to 100000ppm of fluorine or fluoride. This removes the oxide layer formed on the surface of the titanium material by reaction with oxygen in the air with a fluorine-or fluoride-containing gas, cleans the surface of the titanium material, and at the same time, produces a fluoride layer on the cleaned surface. The fluoride layer is stable, thereby preventing titanium from being formed prior to the process of removing the fluoride layerReformation of oxide layer on material base and O₂Adsorption of (3). Then, immediately before the start of rolling, the titanium material base material is exposed by spraying hydrogen gas onto the surface of the titanium material to decompose and remove the fluoride layer on the surface of the titanium material. When the titanium material is rolled, no oxide layer remains on the surface. Because of the high-speed rolling, an oxide layer is not generated on the surface of the titanium material in the rolling process, so that the surface of the titanium material is prevented from cracking in the rolling process.

The present invention is described in detail below.

The fluorine-or fluoride-containing gas used in the process of the invention is an inert gas, e.g. N₂Containing at least one component providing a source of fluorine, e.g. NF₃、BF₃、CF₄、HF、SF₆、F₂. NF in terms of reactivity, ease of control and other properties₃Is most desirable and practical.

As described above, in the process for producing a rolled product of titanium material according to the present invention, the heated titanium material is brought into contact with an inert gas containing fluorine or fluoride before rolling to perform surface treatment of the titanium material. For example, by passing the titanium material through an atmosphere containing a fluorine or fluoride gas and then spraying hydrogen (e.g., H) to the titanium material immediately before rolling is started₂Gas, air or the like; air including hydrogen generated from its moisture) to remove the fluoride layer formed thereon, exposing the substrate. And rolling the material to obtain a rolled product. Fluorine source components in gases containing fluorine or fluoride, e.g. NF₃The concentration of (B) is 1000 to 100000ppm, preferably 20000 to 70000ppm, most preferably 30000 to 50000 ppm. The time for passing through the atmosphere of the fluorine-or fluoride-containing gas may be selectively set depending on the kind, size and heating temperature of the article or the like, and is generally from several minutes to several tens of minutes.

The equipment used in the method for manufacturing a rolled product of titanium material is described in further detail below. As shown in the figure, a gas treatment chamber 2 and two upper and lower spray nozzles for spraying H are arranged in front of the pairs of rolls 4₂A gas nozzle 3. High-temperature thick plate-shaped titanium material 1 discharged from a heating furnace (not shown)Passes through the gas treatment chamber 2 and passes between the two nozzles 3 and is then rolled in a roll 4. The gas introduction pipe 5 and the discharge pipe 6 are fitted to the housing 2a of the gas processing chamber 2. An inert gas containing fluorine or fluoride, such as NF, is supplied to the gas introduction pipe 5 from a gas tank (not shown)₃And N₂The mixed gas of (1). The supplied fluorine or fluoride containing gas is agitated by a fan 7 driven by a motor 8 to form a uniform fluorine or fluoride containing gas atmosphere in the processing chamber 2. The internal temperature of the gas treatment chamber 2 rises due to the passage of the titanium material 1. When the titanium material passes through the gas treatment chamber 2, the oxide film formed on the surface of the material 1 by the reaction of titanium with oxygen in the air is removed from the surface of the titanium material. That is, NF is when exposed to high temperatures₃The gas generates active fluorine, thereby removing organic and inorganic contaminants on the surface of the titanium material. At the same time, the fluorine formed reacts with oxides, for example titanium oxide, on the surface of the material, forming a very thin fluoride layer on the surface of the titanium material.

This reaction converts an oxide layer on the surface of the titanium material into a fluoride layer, and removes O adsorbed on the surface of the titanium material₂. When O is not present₂，H₂，H₂O, the fluoride layer is stable, and is sprayed with H₂Can prevent oxide formation and O adsorption on the titanium material substrate before gas process₂In this fluorination process, the inner wall of the housing 2a also forms a fluoride layer in the initial stage, thus avoiding the need for subsequent application of NF₃Further damage to the inner wall of the housing 2a is caused by the fluoride layer.

H is discharged through a nozzle 3₂NF for gas jet₃A gas-treated titaniummaterial 1. Whereby the fluoride layer is covered with H₂The gas is reduced or decomposed, for example, by a reaction expressed by the following formula, to thereby obtain an active titanium substrate.

When the titanium material 1 in this state is rolled by the rolls 4, the subsequent rolling speed is high, and therefore, no oxide film is formed on the surface of the titanium material again when the titanium material passes through the rolls 4. In the case where the titanium material 1 needs to be rolled by the rolls 4 ten times or more, nitrogen gas may be sprayed to the material 1 at the latter stage of the rolling. Reference numeral 9 in the figure denotes a cover.

As mentioned above, in the method for manufacturing a rolled product of titanium material according to the invention, the titanium material is passed through an atmosphere containing from 1000 to 100000ppm of an inert gas of fluorine or fluoride before rolling. A passive coating, such as an oxide layer, on the surface of the titanium material is converted to a fluoride layer that protects the surface of the titanium material. Therefore, even if there is a time interval between the steps of forming a fluoride layer on the surface of the titanium material and removing the fluoride, the fluoride layer protects and maintains the surface of the titanium material in a good condition, preventing the oxide layer from being formed again on the surface of the material. Since the fluoride layer is decomposed and removed by spraying hydrogen gas just before the start of rolling to expose the titanium base material, the purpose of eliminating cracking on the surface of the titanium material in the rolling of the titanium material is achieved.

Fig. 1 is a view for explanation, showing an apparatus used in an embodiment of the present invention.

The invention is explained below by means of an embodiment.

Example (b):

the thick plate titanium was heated to a red hot state in a furnace and passed through a furnace containing 5000ppm NF₃N of (A)₂A gas treatment chamber in a gas atmosphere, then immediately before rolling, is sprayed H with a spray nozzle₂And (4) rolling the titanium into thin titanium plates by using a roller, wherein the obtained thin titanium plates do not crack at all.

Claims

1. A method of manufacturing a rolled article of titanium material, comprising the steps of: a method for producing a fluoride layer on a surface of a titanium material by bringing the titanium material under heating into contact with an inert gas containing fluorine or fluoride, characterized in that the concentration of the fluorine or fluoride-containing gas in the inert gas is set to 1000 to 100000ppm, and hydrogen gas is sprayed onto the surface of the titanium material immediately before rolling is started to reduce and remove the fluoride layer formed on the surface of the titanium material.