JPS5818980B2 - Copper alloy with excellent ductility at medium and high temperatures - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the improvement of cupronickel, which has excellent ductility in the high temperature range of 400 to 700°C.

Cupronickel is easy to deform and has good corrosion resistance, so it is used as a material for heat exchangers, condensers, etc.

However, this cupronickel is 400 to 700
It does not have sufficient ductility in the high temperature range of ℃ and has embrittlement characteristics that cause intergranular cracks to easily occur.

This intergranular cracking is particularly likely to occur in medium to high temperature ranges, when the residual stress of the material itself is high, or when stress is applied.

The purpose of the present invention is to provide a steel alloy that solves the problem of cupronickel's embrittlement in medium to high temperature ranges.

That is, in the present invention, Ni 5-40%, FeO,4
~2%, Mn 1.2% or less, P O,00' 5~0.
It is a copper alloy with excellent ductility at high temperatures, with the remainder consisting essentially of Cu.

Next, the components of the alloy of the present invention will be explained.

Ni improves the corrosion resistance of copper in chloride solutions.

In particular, the effect of liquid chloride is on dogs.

As the Ni content increases above 5070, this corrosion resistance also improves, but when the Ni content exceeds 40%, pitting corrosion easily occurs in a stationary chloride solution.

Therefore, it is set as Ni5-40.

By adding up to 2 parts of Fe, the corrosion resistance of the copper-nickel alloy in flowing seawater and salt water is improved.

It is highly resistant to erosion and corrosion caused by sand still contained in water, but if it is less than 0.4%, the effect is insufficient.

However, in the temperature range of 400 to 700°C, Fe that exceeds the solid solubility limit precipitates.

Particularly, those precipitated at grain boundaries aggregate and promote embrittlement.

Therefore, Fe O is set at 4 to 2%.

Mn helps deoxidize copper and copper alloys and improves workability.

Furthermore, although Mn slightly improves corrosion resistance in flowing seawater, it is not necessary to add more than 2.

P prevents Fρ grain boundary precipitation at 400 to 700°C, but its effect is small at less than 0,00%.

Moreover, if O or O is contained in an amount exceeding 2%, hot workability will be impaired.

Therefore, Po is set to 0.005 to 0.02%. Next, examples of the present invention will be shown together with comparative examples.

In a 6-tun coreless furnace, a 90/10 Cypronickel ingot (dimensions: thickness 260mm x width 1ooo
, x length 2000 mm') was produced by semi-continuous casting, and one side of the surface was milled by 10rrtrrL to give a thickness of 240TrrrR.

These ingots were heated in a heating furnace at 900 to 950°C, then hot rolled to a thickness of 10 mm.

However, in both cases, the hot end temperature is 700°C or higher.

The obtained plate material was cut into dimensions of 10 mm thick x 150 wr L x 40.0 rran long, and heated at 950°C in the atmosphere for 10 hours.
After heating, cool at room temperature and roll to a thickness of 6rr perpendicular to the rolling direction.
rm high temperature tensile test piece (shape ASTM-E8, pin load tension test piece width 12.5 mm, parallel length 50
．． After holding at 400 to 800° C. for 30 minutes, a medium and high temperature tensile test was conducted at a tensile rate of 1.2 rrrrr L/min.

The test results are shown in Table 2.

As is known from Table 2, the alloy of the present invention has a
It has improved elongation, or ductility, compared to conventional alloys at temperatures as high as 0°C.

In addition, samples No. 1, A2 and A4, which had been heated at 950°C for 10 hours, cooled in the air, and then heat-treated at 500°C for 5 hours, were polished on both sides to a thickness of 0.1 mm.
Approximately 3 volts under a voltage of 70 V in an electrolyte of 5 parts + 5 parts of perchloric acid
The sample was held for 0 seconds, a thin film for electron microscopic observation was prepared, and the morphology of precipitates at grain boundaries was examined.

Electron microscopic images of samples fprJf6.1, A2 and 44 are shown in FIGS. 1, 2 and 3, respectively.

The grain boundary precipitates in sample No. 1 of the conventional material are precipitated in a lamellar shape, and the length is about 1.5μ, but the alloy of the present invention has fine grain boundary precipitates as shown in Figs. 2 and 3. The result is a spherical precipitate, which indicates that the addition of P can suppress the precipitation, aggregation, and enlargement of Fe at grain boundaries.

As stated above, the alloy of the present invention is a material with excellent ductility in the high temperature range of 400 to 700°C compared to conventional alloys, and is suitable as a material for heat exchangers, condensers, etc. It is something.

[Brief explanation of drawings]

Figures 1, 2, and 3 are sample A1 of Example, respectively.
, A2, A40 alloys (magnification 2)
0000 times).

Claims (1)

[Claims] 1 Ni5-40%, Fe0.4-2%, Mn1.2%
Hereinafter, a copper alloy containing 5 to 0.02% of po, o and the remainder substantially of Cu has excellent ductility at high temperatures.