A processing method for reducing annealing dezincification discoloration of gold-like copper alloy strip

Abstract

The application discloses a processing method for reducing annealing dezincification discoloration of gold-like copper alloy strip, and the cast ingot after casting is subjected to hot rolling, on-line quenching and rough machining, and then the plate after the rough machining is subjected to finished product processing; the finished product processing process is in sequence: medium rolling, heat treatment and finish rolling, wherein the medium rolling processing rate is 20-30%, the heat treatment is at 480-510 DEG C for 4-6 hours, and the power of the finish rolling is 30-40%. Through adjusting the process of medium rolling-heat treatment-finish rolling in the production process, the hardness of the gold-like copper alloy strip prepared by the application is higher than that of the traditional process, the deformation energy storage of the material is increased, in the subsequent process of manufacturing coins and commemorative coins, under the same holding time, the same performance is achieved, the recrystallization annealing temperature can be reduced by 30-50 DEG C, and the risk of high-temperature annealing dezincification discoloration caused by high zinc content can be avoided.

Description

Technical Field

[0001] This invention belongs to the field of metal alloy processing technology, and specifically relates to a processing method for reducing the discoloration of imitation gold-copper alloy strip after annealing and dezincification. Background Technology

[0002] Imitation gold-copper alloys are mainly brass-based and bronze-based. Taking brass-based imitation gold-copper alloys as an example, Zn in the alloy can change pure copper from reddish-brown to yellow, and is the main alloying element for producing a golden hue from pure copper. For example, Chinese patent CN102864330 A discloses a gold-containing imitation gold-copper alloy and its preparation method. The percentage composition of this gold-containing imitation gold-copper alloy is: Au: 0.5~10%, Zn: 0.5~40%, Si: ≤1%, RE: ≤1%; colorant: 0.4~5.0%, with the balance being copper. Through the addition of gold, and its synergistic effect with other elements, the alloy's resistance to discoloration and its ease of processing are improved. Currently, the main process for producing this type of imitation gold-copper alloy is: semi-continuous casting - hot rolling - rough rolling - heat treatment - intermediate rolling - heat treatment - finish rolling. However, due to the high zinc content in this imitation gold-copper alloy, after the strip is processed to a finished strip of 1.9mm, in order to achieve the required performance, it needs to undergo high-temperature annealing at 500℃ for 1 hour during the production of coins and commemorative coins. However, during this high-temperature annealing process, dezincification and discoloration are very likely to occur, which seriously affects the quality of the imitation gold-copper alloy. This will not only have a negative impact on society, but will also hinder the development of the imitation gold-copper alloy industry. Summary of the Invention

[0003] To address the problem of zinc dezincification and discoloration that easily occurs during high-temperature annealing (500℃ / 1h) of zinc-containing imitation gold-copper alloys prepared in existing technologies, this invention provides a processing method to reduce zinc dezincification and discoloration of imitation gold-copper alloy strips during annealing. Without changing the strip thickness (1.9mm), the annealing temperature of the material in subsequent coin and commemorative coin production is reduced by adjusting the "intermediate rolling-heat treatment-finish rolling" process. This solves the problem of zinc dezincification and discoloration that may occur during subsequent high-temperature annealing in existing technologies due to the high zinc content of the alloy.

[0004] This invention is achieved through the following technical solution:

[0005] A processing method for reducing the discoloration of imitation gold-copper alloy strip after annealing and dezincification involves hot rolling, online quenching, and rough machining of the cast ingot into finished products. The finished product processing process is as follows: intermediate rolling, heat treatment, and finish rolling. The intermediate rolling rate is 20-30%, the heat treatment is 480-510℃ for 4-6 hours, and the finish rolling power is 30-40%.

[0006] Furthermore, the ingot comprises the following components by mass percentage: 25-30% zinc, 0.5-1.5% tin, 0.6%-1.5% nickel, ≤0.5% other components, and the balance being copper.

[0007] Furthermore, the hot rolling and online quenching process is as follows: the ingot is placed in a walking beam furnace for heating, the ingot temperature is controlled at 830~850°C, the heated ingot is hot rolled into a hot rolled billet with a thickness of 14.5-15.5mm, and the billet is directly water cooled online.

[0008] Furthermore, the roughing process includes rough rolling and post-rough rolling heat treatment. Rough rolling involves cold working 70-80% of the hot-rolled billet after hot rolling and online quenching. The post-rough rolling heat treatment process is 480-510℃ for 4-6 hours.

[0009] Furthermore, the casting process for the ingot is semi-continuous casting.

[0010] Furthermore, the thickness of the finished imitation gold-copper alloy strip is 1.8~2.1mm.

[0011] The beneficial effects achieved by this invention are as follows:

[0012] The present invention provides a processing method to reduce the dezincification and discoloration of imitation gold-copper alloy strip during annealing. This method adjusts the "intermediate rolling-heat treatment-finish rolling" process in the production process to lower the annealing temperature of the material during the subsequent production of coins and commemorative coins. This solves the problem in the prior art where the high zinc content of the alloy may cause dezincification and discoloration during the subsequent high-temperature annealing process.

[0013] The hardness of the gold-copper alloy strip prepared by this invention is improved compared with traditional processes, and the deformation energy storage of the material is increased. In the subsequent production of coins and commemorative coins, the same performance can be achieved under the same heat preservation time. The recrystallization annealing (high temperature annealing) temperature can be reduced by 30-50℃, avoiding the risk of dezincification and discoloration caused by high zinc content during high temperature annealing. Detailed Implementation

[0014] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0015] Example 1

[0016] (1) Casting: Using a semi-continuous casting process, a gold-copper alloy ingot with a zinc content of 26.5wt%, a tin content of 0.83wt%, a nickel content of 1.2wt%, other contents ≤0.5%, and the balance being copper is obtained;

[0017] (2) Hot rolling and online quenching: The ingot prepared in step (1) is placed in a walking furnace for heating. The ingot temperature is controlled at 830~850. The heated ingot is hot rolled into a hot-rolled billet with a thickness of 15mm. The billet is directly water-cooled online.

[0018] (3) Rough processing (rough rolling - heat treatment after rough rolling): The hot-rolled billet after step (2) is subjected to cold processing with 75% power. The heat treatment process after rough rolling is 500 and 5h. The thickness of the strip after rough processing is 3.75mm.

[0019] (4) Finished product processing: The strip after rough processing in step (3) is processed into finished products, including intermediate rolling, heat treatment and finish rolling. The intermediate rolling rate is 25.3%, the heat treatment is 500℃ for 5 hours, and the finish rolling power is 32%. After finished product processing, a gold-copper alloy strip with a thickness of 1.9 mm is obtained.

[0020] Example 2

[0021] (1) Casting: Using a semi-continuous casting process, a gold-copper alloy ingot with zinc content of 26.3wt%, tin content of 0.82wt%, nickel content of 1.1wt%, other contents ≤0.5%, and the balance being copper was obtained.

[0022] (2) Hot rolling and online quenching: The ingot prepared in step (1) is placed in a walking furnace for heating. The ingot temperature is controlled at 830~850. The heated ingot is hot rolled into a hot-rolled billet with a thickness of 15mm. The billet is directly water-cooled online.

[0023] (3) Rough processing (rough rolling - heat treatment after rough rolling): The hot-rolled billet after step (2) is subjected to cold processing with 75% power. The heat treatment process after rough rolling is 500 and 5h. The thickness of the strip after rough processing is 3.75mm.

[0024] (4) Finished product processing: The strip after rough processing in step (3) is processed into finished products, including intermediate rolling, heat treatment and finish rolling. The intermediate rolling rate is 24.3%, the heat treatment is 500℃ for 5 hours, and the finish rolling rate is 33%. After finished product processing, a gold-copper alloy strip with a thickness of 1.9 mm is obtained.

[0025] Comparative Example 1

[0026] Steps (1) to (3) of Comparative Example 1 are the same as steps (1) to (3) of Example 1;

[0027] (1) Finished product processing: The strip after rough processing in step (3) is processed into finished products, including intermediate rolling, heat treatment and finish rolling. The intermediate rolling rate is 40.3%, the heat treatment is 500℃ for 5 hours, and the finish rolling power is 15%. After finished product processing, a gold-copper alloy strip with a thickness of 1.9 mm is obtained.

[0028] The hardness of the imitation gold-copper alloy strips prepared in Examples 1-2 and Comparative Example 1 was tested, and the recrystallization annealing (high-temperature annealing) temperature of the imitation gold-copper alloy strips for preparing coins and commemorative coins was also tested. The results are shown in Table 1 below:

[0029] Table 1. Properties of the gold-plated copper alloy strips prepared in Examples 1-2 and Comparative Example 1

[0030] .

Claims

1. A processing method for reducing discoloration during annealing and dezincification of imitation gold-copper alloy strip, characterized in that, The cast ingots are hot rolled, quenched online, rough rolled, and then heat-treated after rough rolling. The finished product processing process is as follows: intermediate rolling, heat treatment, and finish rolling. The intermediate rolling processing rate is 20-30%, the heat treatment is 480-510℃ for 4-6 hours, and the finish rolling processing rate is 30-40%. The thickness of the imitation gold-copper alloy strip is 1.8-2.1 mm, and the recrystallization annealing temperature is 450-470℃ / h. The ingot comprises the following components by mass percentage: 25-30% zinc, 0.5-1.5% tin, 0.6%-1.5% nickel, ≤0.5% other components, and the balance being copper. The hot rolling and online quenching process is as follows: the ingot is placed in a walking beam furnace for heating, and the ingot temperature is controlled at 830~850. The heated ingot is hot rolled into a hot rolled billet with a thickness of 14.5-15.5mm, and the billet is directly water cooled online. The rough rolling process involves cold working 70-80% of the hot-rolled billet after hot rolling and online quenching. The heat treatment process after rough rolling is 480-510℃ for 4-6 hours.

2. The processing method for reducing discoloration of imitation gold-copper alloy strip after annealing and dezincification according to claim 1, characterized in that, The casting process for the ingot is semi-continuous casting.