JPS5961589A - Molybdenum wire for weld - Google Patents

Abstract

PURPOSE:To maintain the characteristic suitable for working weld by specifying tensile force and elongation percentage as a molybdenum wire for weld. CONSTITUTION:A molybdenum wire for weld having 40-65g/MG tensile strength and >=5% elongation percentage is used. A recrystallization temp. specifies the recrystallization of the molybdenum of the weld in the stage of welding with an Ni alloy wire and the value thereof is preferably >=1,300 deg.C. The molybdenum wire having <=10/100 straightness has excellent linearity and is more preferable. Annealing is preferably performed in a temp. region of 1,200-1,500 deg.C.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a molybdenum well for clamping a tungsten filament of a halogen lamp, and more particularly to a molybdenum wire having properties suitable for processing the well.

[Technical background of the invention and its problems]

Halogen lamps filled with an inert gas containing a trace amount of halogen substances have high brightness and long life, and are therefore beginning to be widely used as lamps for automobiles.

The lighting section of this halogen lamp has a structure in which, for example, a tungsten filament is clamped by a pair of molybdenum wells. This lighting section is usually manufactured as follows.

First, a molybdenum wire of a predetermined length and diameter is prepared, and one end of the wire is processed into a flat shape. Next, this flattened portion is bent into an iU-shape, and the tungsten filament is held between the bent portions. On the other hand, the other end of the molybdenum wire is welded to a sealing alloy wire, for example, a nickel alloy wire, and the nickel alloy wire is sealed with glass.

In manufacturing such a lighting unit, the following points occur, which are the main causes of a decrease in the profit margin.

First, when one end of the molybdenum wire is flattened, cracks such as cracks and cracks occur along the wire axis direction. The second is when the flattened part is bent.
Cracks such as peeling occasionally occur on the back side of the bent part. Another problem is that molybdenum may become brittle at the welded portion when welding with N1 alloy wire.

[Purpose of the invention]

The object of the present invention is to provide a molybdenum wire well that does not suffer from the above-mentioned problems.

[Summary of the invention]

The present inventors investigated in detail the relationship between the above problems and the characteristics of the molybdenum wire used, and found that 4'f, tensile strength, and bending rate are important factors. That is, we focused on the phenomenon that if the tensile strength is low, cracks, cracks, etc. are likely to occur during flattening, and if the elongation rate is low, cracks are likely to occur during bending. We also focused on the phenomenon that when the recrystallization temperature is low, the welded part is more likely to become brittle when the welding temperature is high.

According to the inventors, satisfactory properties can be obtained as a molybdenum wire for wells by biasing the properties of tensile strength of 40 to 65 g/MG and elongation of 5% or more.

Moreover, it is preferable that the recrystallization temperature is 1300° C. or higher.

Tensile strength is a factor that determines cracks in wells during flattening and bending, and this value is 40 j; l/
If it is less than MG or exceeds 6597MG,
In both cases, cracks such as cracks, cracks, and chips are likely to occur during processing.

The elongation rate is a determining factor similar to the tensile strength, and if this value is less than 5, cracks are likely to occur during flattening and bending.

In addition, the recrystallization temperature determines the recrystallization of molybdenum in the well during welding with Ni alloy wire, and if this value is less than 1300°C, the well in the weld will become brittle when the welding temperature is high. Sometimes.

Furthermore, a molybdenum wire having the above-mentioned properties and having a straightness of 10/100 or less is more preferable since it has excellent straightness. Straightness is indicated by the maximum distance (pus) between the chord and arc of an arbitrary 100-ran molybdenum wire placed on a flat surface and bowed.

The well of the present invention is manufactured as follows.

First, a molybdenum wire of a certain diameter is wired using a conventional method. Next, this is electrolytically polished in, for example, an aqueous solution of 1 sodium hydroxide, and a predetermined amount of the bare surface is dissolved.

The obtained wire is annealed at a predetermined temperature in a reducing atmosphere, for example, a hydrogen atmosphere, and is used as a wire for C-wells.

The annealing temperature at this time has a great effect on the tensile strength and elongation of the wire. The relationship is shown in the figure. In the figure, A and B are curves related to tensile strength and elongation, respectively. In addition, the unit of tensile strength: g/MG means the breaking strength (,9) against the weight of the wire (t(+IIfi') (i.e., represents the cross-sectional area of the wire) per 200 mm of the wire length, Further, the elongation rate of 2% means the percentage of the elongation amount up to the time of breakage with respect to the length of the wire rod in the elongation test section j.

As is clear from the figure, annealing is performed at 1200 to 1500℃.
It is desirable to carry out the test in a temperature range of

However, smoothing the surface by electrolytic polishing or the like is effective for facilitating subsequent processing and preventing surface cracking.

[Embodiments of the invention]

Tensile cuff 0 g/MG % elongation rate 3%, recrystallization temperature 1
Characteristics of 650℃? : All of the molybdenum wires with a set diameter of 0.5 mm were drawn by a conventional method to obtain a wire with a wire diameter of 0.35 wn.

This wire was electrolytically polished in a 25 cl) NaOf (aqueous solution) to remove 3 wt% of optical surface molecules.

Next, this wire was placed in a hydrogen annealing furnace at 10°C.
It was annealed by passing through the sample at a linear velocity of 5+y7mlnO. The obtained wire has a tensile strength of 52. ．． 9/MG% elongation rate was 12 inches, and the recrystallization temperature was 1700°C.

This wire was cut into pieces to produce 200 wells using a conventional method. A total of 8 pieces were defective during flattening, bending, and welding. Profit rate: 96chi.

Contrary to this:, baking, l'I'1' treatment is not applied &! The same number of Wells gold pieces were produced using the moon. Number of defective products: 15
The yield was 22.5 pieces.

[Effects of Hatsutsu J]

As is clear from the above description, the molybdenum wire having the characteristics according to the present invention is very useful for manufacturing wells.

[Brief explanation of drawings]

The figure is a relationship curve between the tensile strength and elongation of a molybdenum wire rod and annealing temperature, where A represents the tensile strength and B represents the elongation.

Claims (1)

[Scope of Claims] (Li) A molybdenum wire for wells having the properties of tensile strength of 40 to 6 s g/MG% and elongation of 5 cm or more. (2) Claim 1, wherein the recrystallization temperature is 1300°C or higher. A molybdenum wire for a well as described in claim 1. (3) A molybdenum wire for a well as described in claim 1, which has a straightness of 10/100 or less. A molybdenum wire for wells according to claim 1. (5) A molybdenum wire for wells according to claim 4, which is obtained by smoothing the surface before heat treatment.