JPS60211026A - High strength cu alloy containing dispersed boride and having superior resistance to corrosion by molten metal and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a high strength Cu alloy contg. dispersed borides and having superior resistance to corrosion by molten metal by blending Cu with specified amounts of B, Zr and/or Ti and one or more among Cr, Cd and Ni. CONSTITUTION:The composition of a Cu alloy is composed of, by weight, 0.15- 2% B, 0.75-10.5% Zr and/or 1.2-7.5% Ti, one or more among 0.1-1.5% Cr, 0.1-3% Cd and 0.5-6% Ni, and the balance Cu with inevitable impurities. The Cu alloy is cold worked at 40-90% working rate and heat reated by holding at 425-550 deg.C for 10min-3hr.

Description

[Detailed description of the invention] [Industrial application field] This invention has high high temperature strength and conductivity, and furthermore, Zn
The present invention relates to a boride-dispersed Cu alloy that exhibits excellent corrosion resistance against molten metals such as A1, A1, or alloys thereof, and a method for producing the same.

[Conventional technology]

In general, for example, spot welding electrodes have properties such as good conductivity, heat conductivity, arc resistance, oxidation resistance, ease of processing, and mechanical strength at room and high temperatures, and do not alloy with the workpiece. It is required to have the following characteristics. For this reason, pure copper is used to manufacture electrodes used for spot welding light alloys and Cu alloys, and Cd is used for steel.

Or, W, Co, Be, Ti, Nl, Zr
, and one or two of alloy components such as Al11
Currently, Cu alloys containing more than one species are used.

On the other hand, in spot welding, the welding surface becomes hot due to the large force and large welding current applied to the welding surface during welding, resulting in contamination at the electrode tip, and this contamination increases as the number of welding points increases. The tip of the electrode is corroded and deformed, and the welding current density decreases accordingly, and as a result, the welding strength also decreases, but the life of the electrode is defined as the point at which a predetermined welding strength cannot be obtained. For example, when spot welding Zn-plated steel sheets,
Zn has a very low melting point of 420°C, and therefore the Zn plating melts before forming a nugget. This molten Zn is picked up by the electrode tip and alloyed, and the alloyed electrode tip is corroded. As the electrode becomes more easily deformed, the diameter of the tip increases, while the compatibility between the base metal and the electrode tip deteriorates, resulting in a decrease in welding current density and the ability to achieve the desired welding strength. It is considered as the lifespan.

(Problems to be Solved by the Invention) However, as mentioned above, conventional Cu alloy electrodes are easily alloyed with molten metals such as 7N, At, or alloys thereof, and are easily corroded and deformed. However, the service life is extremely short, and the production line must be stopped to clean or replace the electrodes every time there is a trace, resulting in a significant economic loss.

[Means for solving problems]

Therefore, from the above-mentioned viewpoints, the present inventors have developed a material that is not affected by molten metal, has a wet strength and an am conductivity, and is particularly suitable for use in manufacturing electrodes for welding such as spot welding. As a result of conducting research to obtain a material with a high content, the result was 3:0.15 to 2% in weight% (all percentages below indicate weight%).

Contains, and furthermore, Zj: 0.75-10.5%.

Ti: 1.2-7.5%.

One or two of the following: Cr: 0.1-1.5%.

Cd: 0.1-3%.

Ni: 0.5-6%.

40 to 90% of Cu alloy containing one or two of
After cold working at a processing rate within the range of 425 to 55
When heat treatment is carried out at a temperature in the range of 0°C for a period of time in the range of 10 minutes to 3 hours, Z' and a part of Ti,
Or, Cd, and Ni are precipitated in the matrix in the form of simple metals and/or intermetallic compounds by the heat treatment, and further, borides of Z' and T1 are uniformly dispersed in the matrix strengthened by precipitation in this way. Cu alloys with such a structure have excellent corrosion resistance against molten metals, high-temperature strength, and high conductivity, and are therefore used as welding electrodes for spot welding, as well as die-casting metals. They discovered that it exhibits extremely excellent performance when used in the production of molds, continuous casting molds, and tuyeres for smelting furnaces.

This invention was made based on the above findings, and the reason why the component composition, processing rate, and heat treatment conditions were limited as described above will be explained below.

A, Ingredient composition (a) B The component contains boride that crystallizes by combining with Z and T1 during casting, and has stability against molten metals such as Zn and A1.
That is, the alloy is alloyed with these molten metals and softened, and 1
11 It has the effect of imparting properties to the alloy to prevent deformation and improving high-temperature strength and high-temperature hardness, but if its content is less than 0.15%, the desired effects cannot be obtained. On the other hand, if the content exceeds 2%, the high temperature strength and cold workability will deteriorate, so the content was set at 0.15 to 2%.

(b) As mentioned above, some of the Zr and l'-17r and Ti components combine with all the B to crystallize and form boride, providing corrosion resistance to molten metals, high-temperature strength, and high-temperature hardness. Zr: 0.7.
If Zr: less than 5% and T1: less than 1.2%, the desired effect cannot be obtained; on the other hand, Zr: 1G, 5%, Ti: less than 1.2%.
If each content exceeds 7.5%, cold workability will deteriorate, so the respective contents should be adjusted to Z
r: 0.75~10.5%, Ti: 1°2~
It was set at 7.5%.

(C) Or, Cd, and Ni These components all precipitate into the base material by heat treatment and have the uniform effect of improving the strength of the base material at room temperature and high temperature, but Cr: less than 0.1%, respectively. When Cd: less than 0.1% and Ni: less than 0.5%, the desired effect of improving the above action cannot be obtained, while cr:
i, s%, Cd: 3%.

and Ni: If the content exceeds 6%, cold workability deteriorates, so the respective contents are set to Cr: 0.1 to 1.5% and Cd: 0.1 to 3%. , and Ni: 0.5 to 6%.

B. Cold working rate During the heat treatment in the post-process, cold working removes the remaining Ti and 7r that have formed borides, as well as C''.

It is applied to facilitate the precipitation of Cd and Ni, but if the processing rate is less than 40%, the desired precipitation cannot be achieved, while even if the processing rate exceeds 90%, it will be difficult to achieve the desired precipitation. Since no precipitation effect appears and a sufficient amount of precipitation can be obtained with a processing rate of 90% or less, the processing rate was set to 4.
It was set as 0 to 90%.

C0 heat treatment conditions If the heat treatment temperature is less than 425°C and the holding time is less than 10 minutes, precipitation will be insufficient and the desired properties cannot be imparted to the alloy. If it exceeds 3 hours, it becomes over-aged and the desired properties cannot be secured, so the heat treatment temperature was set at 425 to 550°C and the holding time was set at 10 minutes to 3 hours.

〔Example〕

Next, the Cu alloy of the present invention will be explained using Examples while comparing it with a conventional example.

Molten metals having the final component compositions shown in Table 1 were prepared under normal conditions using a vacuum induction furnace with mechanical stirring, and cast into ingots at a temperature of 2850°C. After hot forging and hot rolling to obtain a hot-rolled plate with a thickness of 36 Jll, this hot-rolled plate was then subjected to solution treatment at a temperature of 900°C for 1 hour. According to the method, the present invention C is subjected to cold rolling and heat treatment under the conditions shown in Table 1.
Plate materials of u alloys 1 to 26 and conventional OL1 alloy 1.2 were manufactured, respectively.

The resulting Cu alloys 1 to 26 of the present invention and conventional C
For u alloy 1.2, the Vickers hardness at room temperature and 500° C. was measured, and a molten Zn immersion test was conducted. In the molten ZN immersion test, a test piece of thickness: 3M x width: 25 shoes x length: 35 shoes was cut out by machining, and the temperature:
After being immersed in molten Zn at 500° C. for 2 hours and taken out, the Zn adhering to the surface was removed with 50% hydrochloric acid and weighed, and the corrosion loss was calculated. These measurement results are also shown in Table 1.

As shown in Table 1, the Cu alloys 1 to 26 of the present invention are:
Both exhibit higher high-temperature hardness than the conventional Cu alloy 1.2, which does not contain B, that is, has no boride precipitation in the matrix, and this indicates that the Cu alloy of the present invention has excellent high-temperature strength. It is also clear that the Cu alloy of the present invention has superior molten Zn corrosion resistance compared to conventional Cu alloys.

Next, regarding the electrodes of the present invention Cu alloy 21 and the conventional Cu alloy 1, the electrode shape: tip diameter 5IMφ x body diameter 12am+
φ, object to be welded: thickness 0.8. Zn-plated steel plate, welding mode: overlap welding, welding current: 8500A, pressure force 20
Spot resistance welding was performed under the condition of 0 kg, and its service life was measured. As a result, the electrode made of Cu alloy 21 of the present invention was able to perform continuous spot welding of 4500 points (average value of 10 operations), whereas the conventional electrode made of Cu alloy 1 had a service life of 1000 points. reached.

In addition, Cu alloys 1 to 26 of the present invention all have 55 to 70
% (IAC 8%), indicating good conductivity.

As mentioned above, the CU gold alloy of the present invention has particularly excellent molten metal corrosion resistance and high-temperature strength, and also has good electrical conductivity, so it is suitable for use with Zn-plated steel sheets, AI-plated steel sheets, etc. It has industrially useful properties such as exhibiting outstanding performance when used in spot welding electrodes and other electrodes, die-casting molds and their parts, continuous casting molds, and even tuyeres. It is.

Applicant: Mitsubishi Metals Corporation Agent Tomi 1) Kazuo and 2 others

Claims (2)

[Claims] (1) B: 0.15-2%. Further, 7r: 0.75 to 10.5%. ■i: 1.2-7.5%. One or two of these and cr: 0.1-1.5%. Cd: 0.1-3%. Ni: 0.5-6%. A high-strength boride-dispersed Cu alloy with excellent molten metal corrosion resistance, characterized by containing one or more of the following, with the remainder consisting of Cu and unavoidable impurities (weight percent). . (2) B: 0.15 to 2%. and further contains one or two of the following: Z': 0°75-10.5%; Ti: 1.2-1.5%; and Or: 0.1-1.5%. Cd: 0.1 to 3%. Ni: 0.5 to 6%. A Cu alloy containing one or more of the following, with the remainder consisting of Cu and unavoidable impurities (the above weight %) , after performing cold working at a processing rate within the range of 40 to 90%, heat treatment is performed at a temperature within the range of 425 to 550°C for a time within the range of 10 minutes to 3 hours. A method for producing a high-strength boride-dispersed Cu alloy with excellent molten metal corrosion resistance.