JPH0234746A - High purity metallic chrome wire rod and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture the title wire rod having excellent malleability and ductility and easy to be subjected to secondary working by heating an ingot of high purity metallic Cr to the range of ductility-brittleness transition temp. in Cr and subjecting it to wire drawing at the specific reduction rate. CONSTITUTION:Metallic Cr having >=99.9% high purity is manufactured by the electrolysis of a Cr salt soln. or the like and is heated to 300 to 800 deg.C, i.e., to the ductility-brittleness transition temp. in Cr. In this case, since the above ductility-brittleness transition temp. is more reduced the more the purity of Cr is heighten and the contamination caused by impurities can nearly be neglected, the plastic working having no contamination caused by impurities is permitted even if subjected to wire drawing at >=70% reduction of area, by which the metallic Cr wire rod having >=10% elongation of tensile characteristics at room temp. and having no faults such as cracking even if subjected to repeated wire drawing can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a highly pure metal chromium wire and a method for producing the same.

[Prior Art] Metallic chromium has excellent chemical resistance such as acid resistance and alkali resistance even at high temperatures, and excellent weather resistance, and is one of the extremely useful metals.

However, despite having these excellent properties, metallic chromium wires have low toughness and are difficult to process at low temperatures, so with the exception of a few metal chromium wires, they have hardly been put into practical use, and furthermore, they have not been put into practical use. The wire rods that have been tried cannot necessarily be said to have sufficient characteristics to be used as practical materials.

Conventionally, the following methods are known as methods for forming alloys containing chromium.

l) A method for producing a Cr-based wire rod with good cold forgeability, in which the entire length of the coil is made into a single structure in a hot rolling process. (Tokuko Showa 51-
No. 23934) 2) Brialloy powder is atomized by gas atomization from a number of stages of starting metal raw materials to a specified particle size according to the carbon content, then compacted, hot forged, hot rolled, etc. A method for manufacturing carbon-cobalt-based alloy bars and wires. (Unexamined Japanese Patent Publication No. 57-188634) 3) High Mn-based Mn-Cr-
The content of Cr5Ni and N in Ni-based austenitic steel is adjusted to 113, hot-rolled under specific conditions, and cooled to produce a non-magnetic steel wire (Japanese Unexamined Patent Publication No. 61-37953). be.

However, the above conventional technology has the following problems. That is, the above-mentioned three types of thin wire manufacturing methods are methods for manufacturing wire rods of alloys containing about several to 35% chromium, and cannot be applied to metals with extremely poor workability such as metallic chromium.

In addition, method 3) above requires high processing temperatures, so even if this method is applied to metal chromium, whose toughness is degraded by impurities (especially nitrogen, oxygen, and carbon), the obtained wire will not contain the impurities mentioned above. It is conceivable that the mechanical properties would be extremely low due to the contamination.

[Means for Solving the Problems] Metal chromium is generally known as a metal that is difficult to process.

Metallic chromium is ductile at high temperatures, but after a certain temperature (ductile-brittle transition temperature), the ductility decreases significantly below that temperature. Therefore, metal chromium has poor workability near room temperature, and plastic working (for example, manufacturing a wire rod with an area reduction rate of 90% or more) is extremely difficult.

Also, as mentioned above, metallic chromium is nitrogen and oxygen.

It is sensitive to impurities such as carbon, and becomes extremely brittle in the presence of these impurities, so hot working at high temperatures with severe impurity contamination cannot be applied to metal chromium.

The inventors of the present invention have carried out intensive research into the production of metallic chromium wire rods, and have found that metallic chromium with a purity of 99.9% or higher can be processed into thin wires by heating at a temperature near the ductile-brittle transition temperature. It was discovered that a highly pure metal chromium wire can be obtained by carrying out this process, leading to the present invention.

That is, the present invention has a tensile property of 1 at room temperature.
In a method for producing a metal chromium wire rod with a purity of 99.9% or more and an elongation a of 0% or more and a metal chromium wire rod by heating fine wire processing of a gold-backed ROM ingot, using 99.9% or more metal chromium, The present invention provides a method for producing a metal chromium wire, which is processed in the ductile-brittle transition temperature range of chromium to produce a wire having room temperature tensile properties of 10% or more elongation.

It is generally believed that the difficulty of processing metal chromium is due to its body-centered cubic lattice crystal structure, which causes embrittlement due to interstitial impurity elements such as oxygen, nitrogen, and carbon. Further, it is known that the ductile-brittle transition temperature of metallic chromium changes depending on its purity, and as the purity of metallic chromium increases, the ductile-brittle transition temperature decreases, and is usually 300 to 800°C.

In the production method of the present invention, purity of 99.9% is used as a raw material.
The above metal chromium is used. By using high-purity metallic chromium as a starting material, the ductile-brittle transition temperature can be further lowered, making it possible to perform plastic working at a temperature where impurity contamination can be ignored. If the temperature is around the ductile-brittle transition temperature, cracks will not occur in the metal even if the thin wire processing is performed by edge turning, and a metal chromium wire rod with a desired wire diameter can be obtained.

Further, it is preferable that this heating thin wire processing is repeated until the area reduction rate is 70% or more. The resulting wire has excellent tensile properties.

The area reduction rate in this case is 1 to 10% for one thin wire processing.
It is preferable that If the area reduction rate is less than 1%, only the surface of the metal will be processed and the internal structure will not be adjusted, while if it is greater than 10%, there is a risk that cracks will occur in the metal.

A wire rod thinned under such conditions has an elongation of 10% or more in terms of tensile properties at room temperature.

Further, the metal chromium used in the production method of the present invention preferably has a purity of 99.9% or more, and contamination with impurities such as carbon, nitrogen, and oxygen should be avoided as much as possible. This is because the presence of these impurities reduces the toughness of the obtained wire.

Such high-purity metallic chromium can be obtained by electrolyzing a chromium salt solution, or by purifying a chromium salt solution by a solvent extraction method and oxidizing the obtained chromium salt solution or the chromium salt obtained from this solution. The obtained chromic acid can be reduced by a hydrogen reduction method or the like to use 1-1 metal chromium or the like.

The method for producing metal chromium salt for fine wire processing (JT) is not particularly limited as long as it can prevent contamination by impurities such as carbon, nitrogen, oxygen, etc., but - for example, arc melting in an inert gas. There is a method for producing metallic chromium ingots.

If the metal chromium wire produced by the manufacturing method of the present invention is subjected to an appropriate heat treatment in an inert atmosphere or a reducing atmosphere to alleviate processing strain and residual stress inside the wire, the strength will be increased. .

Although the ductility, hardness, etc. are reduced, it is also possible to further improve the ductility, toughness, and mechanical properties of elongated bamboo.

[Effects of the invention] The wire rod of the present invention has higher malleability and ductility than metal chromium wire rods produced by conventionally known methods, and can be easily processed into secondary processing, and can be processed into any shape. . Therefore, this metal chromium wire is used as it is or after secondary processing, and is exposed to high temperatures and strong acids.

It can withstand use even under harsh conditions such as strong alkalis. Further, according to the manufacturing method of the present invention, a metal chromium wire rod having any wire diameter and having toughness can be obtained with a relatively simple operation.

[Examples] The present invention will be explained below with reference to Examples, but the present invention is not limited to these examples.

Example I 300 g of metallic chromium having the composition shown in Table 1 was melted under 1 atm of argon gas using an inert sous-arc melting furnace (Max, 100 OA, 20 V) to produce a 285 g ingot. ．． A cylindrical metal chrome rod of OX5cm was cut out.

Then insert this metal chrome rod into an inert atmosphere furnace,
Hot swaging processing was performed by heating to a temperature of 500°C. The processing conditions were a temperature of 500° C. and an extrusion force of 5 tons. The area reduction rate is 5 to 10% at each time, and the thin wire is processed from the cross-sectional area of the raw metal chromium rod until the area reduction rate is 95%.
It was made of metal chrome wire.

When a tensile test was performed on the obtained metal chromium wire at room temperature, it showed an elongation of 12%.

Example 2 Using the same metal chromium as in Example 1 as a starting material, a metal chromium rod was produced by the same method as in Example 1, and hot swaging was performed under the same conditions as in Example 1. The obtained metal chromium wire was heat treated in a reducing atmosphere at a heat treatment temperature of 800°C and held for 0413 hours.
A tensile test at room temperature showed an elongation of 16%.

Examples 3 to 6 Using the same metal chromium as in Example 1 as a starting material, metal chromium ingots were produced by the same method as in Example 1, and Table 2
Hot swaging processing was performed under the conditions shown in . Thereafter, the tensile properties of the metal chromium wire which was subjected to the same heat treatment as in Example 2 are shown in the same table.

Table 1 Table 2 Tosoh Corporation

Claims (1)

[Scope of Claims] 1) A metal chromium wire with a purity of 99.9% or more and having an elongation of 10% or more in tensile properties at room temperature. 2) In the method of manufacturing a metal chromium wire rod by heating fine wire processing of a metal chromium lump, 99.9% or more of metallic chromium is used, processing is performed in the ductile-brittle transition temperature range of chromium, and the tensile properties at room temperature are 10% or more. 1. A method for producing a metal chrome wire rod, characterized in that the wire rod has an elongation of . 3) The manufacturing method according to claim 2), wherein the metal chromium wire has an area reduction rate of 70% or more.