A heat treatment process of nickel-tungsten alloy electroplating layer on copper plate of continuous casting crystallizer

Abstract

The invention discloses a heat treatment process for a copper-plate nickel-tungsten-alloy electroplated layer of a continuous-casting crystallizer. The heat treatment process is characterized by comprising the following steps of thermally preserving the electroplated layer for 1.5h to 1.8h in a vacuum heat treatment furnace under the temperature of 640 to 660 DEG C, cooling down the electroplated layer along with the furnace, and then thermally preserving the electroplated layer for 1h to 1.2h under the temperature of 450 to 470 DEG C. Compared with the primary vacuum heat treatment process, the heat treatment process can improve the micro-hardness of the electroplated layer at the plating state by 118HV to 127HV and reduce the internal stress by 34MPa to 42MPa, slowing down the corrosion rate by 0.008mm / a to 0.014mm / a, the corrosion-resisting property is improved, the heat-fatigue resistance is increased by 32 to 42 weeks, the bonding property of the electroplated layer, the abrasion resistance, the heat cracking resistance and the heat fatigue resistance of the electroplated layer can be obviously improved; the average service life of the crystallizer is proved in the real production to be increased by 40 furnaces, and the service life of the continuous-casting crystallizer can be more effectively improved.

Description

technical field [0001] The invention belongs to the technical field of surface treatment, in particular to a heat treatment process for a nickel-tungsten alloy electroplating layer on a copper plate of a continuous casting crystallizer. Background technique [0002] With the continuous development of the economy, higher and higher requirements are put forward for the performance of the coating on the surface of the continuous casting mold. People often develop new alloy coatings and composite coatings with superior performance to increase the amount of steel passing through the mold and reduce the tonnage. cost. But at present, most of the coatings are still in the research stage and have not been applied in practice, so it is no longer possible to increase the amount of steel passing through the mold simply by obtaining new coatings. [0003] The working temperature of the continuous casting mold is generally above 400°C. After the alloy coating is plated on the copper pla...

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Problems solved by technology

But at present, most of the coatings are still in the research stage and have not been applied in practice, so it is no longer possible to increase the steel throughput of the mold only by obtaining new coatings.

[0003] The working temperature of the continuous casting mold is generally above 400°C. After the alloy coating is plated on the copper plate of the mold, a vacuum heat treatment is often performed to improve the microhardness and corrosion resistance of the alloy coating and reduce the internal stress. A heat treatment in a temperature range cannot make all properties optimal at the same time. Researchers will determine a certain temperature to make the overall performance relatively optimal, but all properties cannot be optimized to the greatest extent.

[0004] After the nickel-tungsten alloy coating is electroplated, the hardness of the coating increases after vacuum heat treatment, but due to the floating of tungsten, the hardness of the coating changes greatly along the depth direction. The loose structure affects the improvement of the surface hardness of the coating

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