JPS60138034A - Copper alloy having superior corrosion resistance - Google Patents

Abstract

PURPOSE:To obtain an inexpensive Cu alloy having superior corrosion resistance by providing a specified composition consisting of Zn, P, Sn, Al, Fe, Pb and Cu. CONSTITUTION:This inexpensive Cu alloy having superior corrosion resistabce consists of, by weight, 10-<25% Zn, 0.005-0.070% P, 0.05-1.0% Sn, 0.005- 1.0% Al and the balance Cu with inevitable impurities or further contains 0.005-1.3% in total of 0.005-1.0% Fe and/or 0.005-0.3% Pb and has improved resistance to erosion corrosion. The Cu alloy is obtd. by adjusting the grain size of a Cu alloy having said composition to <=0.015mm. by final annealing, and it is most suitable for use as a material for a heat exchanger, especially for the pipe of a condenser.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copper alloy that has excellent corrosion resistance and is suitable as a material for heat exchangers, particularly as a material for condenser tubes.

Brass-based alloys generally have good mechanical properties and formability,
Because it is cheaper than other copper alloys, it is used in a wide range of applications, and is often used as a material for condenser pipes.

In the condenser pipe, the flow velocity may locally increase at one bend on the inner surface near the inlet for freshwater or seawater.

In places where turbulence occurs, so-called erosion corrosion occurs, which causes severe corrosion.

Conventionally, Admiralty brass (Cu-Zn-8u alloy) and aluminum brass (0u-Zn-Al-As alloy) have been used as condenser pipe materials for freshwater or seawater.
At present, Admiralty brass is only used for freshwater applications due to insufficient erosion and corrosion resistance, and aluminum brass also uses anti-corrosion methods that supply small amounts of iron ions into seawater. be. As described above, existing alloys are not necessarily satisfactory in terms of erosion and corrosion resistance, which are the most important properties for condenser pipe materials, and there has been a desire for the development of further improved and inexpensive materials.

In view of this, the present invention aims to provide an inexpensive alloy with excellent corrosion resistance that further improves the erosion and corrosion resistance of conventional brass alloys.

The present invention has a zinc content of less than 10 to 25wt and a phosphorus content of less than 0.005wt.
~0.070 wtqb, tin 0.05-1. Owtl
, 7 contains the miniram αos ~ t o wtl,
Furthermore, iron [LOO5~1. Owtl, lead 0.005
~l 3 wtl any one or two types in total 0.0
Including 05~1.3w.

Copper alloy with excellent corrosion resistance consisting of balance copper and unavoidable impurities, zinc 10-25 wt less than 9I+, phosphorus α 005-0.070 wt, tin 0.05- 1. Owt
Unfortunately, Aluminum Q, 05-1. Including Owt staff.

Furthermore, iron [LOO5~1.0Wt'fi, lead 0.005
~0.5wt1 any one or two types in total o, o
It is a copper alloy with excellent corrosion resistance, containing 1.3 wtl of os and the balance being copper and unavoidable impurities.

Next, the reasons for limiting the alloy components constituting the alloy of the present invention will be explained. The reason why the zinc content is set to be less than 10 to 25 Wt4 is that if the zinc content is less than 10 wt%, the erosion and corrosion resistance cannot be improved by containing zinc; This is because local corrosion becomes noticeable if the temperature is higher than that. The phosphorus content is Q, 005 to 0.
The reason for setting it as 070wt% is that the phosphorus content is αO05wt.
This is because when the phosphorus content is less than 4, no improvement in erosion and corrosion resistance is observed even if tin and aluminum are co-added, and on the other hand, when the phosphorus content exceeds α070 wt'l, signs of intergranular corrosion are observed. be. The tin content is αo5~t o wt
The reason for this is that when the tin content is less than 105wt4, the co-addition of phosphorus and aluminum does not improve the corrosion resistance. O
This is because the effect becomes saturated when it exceeds wtl.

Aluminum content is 0.05-1. The reason why it is set as Owtl is that when the aluminum content is less than α05wt%, no improvement in erosion and corrosion resistance is observed even if phosphorus and tin are co-added;
This is because the effect becomes saturated when it exceeds Owtl.

The iron content is α005~1. The reason for choosing Owtl.

When the iron content is less than 0.005 wt'1, no improvement in erosion and corrosion resistance is observed; This is because the effect becomes saturated when it exceeds Owtl.

What is the reason for setting the lead content to α005 to α3 wtl?

This is because when the lead content is less than α o s wt%, no improvement in erosion resistance and corrosion resistance is observed, and on the contrary, when the lead content exceeds 0.5 wtl, the workability decreases.

Furthermore, the reason why the crystal grain size was limited to (1015 m or less) is
This is because when the grain size exceeds 0.015 m, erosion and corrosion resistance decreases and dezincification corrosion becomes more likely to occur.

Since the alloy of the present invention exhibits good corrosion resistance, particularly erosion and corrosion resistance, it is suitable as a material for condenser pipes.

Examples Alloys having the various compositions shown in Table 1 were melted, hot-rolled and appropriately annealed, and then cold-rolled into a plate with a thickness of 1 inch.Finally, annealed at various temperatures, various The grain size was adjusted.

These samples were immersed in artificial seawater and rotated at high speed to examine their erosion and corrosion resistance.

The evaluation method was to express the erosion degree w/yθar based on the change in weight before and after the 250 hr test.

As can be seen from Table 1, the alloy of the present invention has excellent erosion resistance.
It was found to have excellent corrosion resistance. Among the alloys of the present invention, alloys with a grain size of 0.015 square centimeters or less have better erosion and corrosion resistance.

Claims (2)

[Claims] (1) Zinc 1o~less than 25Wt4, phosphorus 0.005~
0.070wt%, tin 0.05-1. Owt4,
Aluminum CL 05-1. 'Owtl and further contains iron 0.005-1. Owt, lead α005~0.3
Total o, o o of any one or two types of wt staff
Copper alloy with excellent corrosion resistance, containing s~1.3 wt, the balance being copper and unavoidable impurities. (2) Zinc 10 to less than 25 wt%, phosphorus o adjusted so that the grain size is 11.0151 m or less in the final annealing
, os~0.070wt, tin α05~1.
Owt staff. Aluminum α05~1. Contains Owtl and further contains iron 0.005-1. Owt, lead o, o o s~0
, 3wt4 inner one or two types in total n, oos~
A copper alloy with excellent corrosion resistance that contains 1.3wt4 and the balance is copper and unavoidable impurities.