Annealing method of 3Cr17NiMo electroslag ingot

Abstract

The invention provides an annealing method of a 3Cr17NiMo electroslag ingot. The annealing method comprises the following steps that the 3Cr17NiMo electroslag ingot is demolded, and then annealing is conducted; the annealing method comprises the following steps that the heat preservation of a demolded product is conducted at 605-635 DEG C for 4.6-5.0 hours; then first cooling is conducted and the temperature reaches to 185-200 DEG C, then the temperature is raised to 750-770 DEG C, and the heat preservation is conducted for 20-22 hours; then secondary cooling is conducted and the temperature reaches to 80-120 DEG C, then the temperature is raised to 750-770 DEG C, and the heat preservation for is conducted for 20-22 hours; and third cooling is conducted and the temperature is less than or equal to 400 DEG C, and discharging is conducted. According to the annealing method, the charging furnace temperature of the electroslag ingot is controlled to be 605-635 DEG C, the heat preservation is conducted for 4.6-5.0 hours, the temperature of an electroslag ingot body is made to be uniform, thermal stress is eliminated, and then cooling transformation is carried out, and high-temperature tempering is carried out twice, so that transformation stress is eliminated.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to an annealing method for a 3Cr17NiMo electroslag ingot. Background technique [0002] 3Cr17NiMo is a high-corrosion-resistant, high-polish plastic mold steel, especially suitable for plastic injection molds and blow molds for thermoplastic corrosion plastics, and is also widely used in cosmetic molds, stationery molds and other plastic molds that require polishing. After electroslag remelting, the steel is pure, dense in structure, and uniform in composition and organization, but this series of steel electroslag ingots are prone to bursting and causing losses. [0003] In order to ensure the quality of 3Cr17NiMo series high-end plastic mold steel products, the product adopts the electroslag remelting process, but due to the following reasons, the electroslag ingots of this steel type are prone to bursting, resulting in losses: (1). The gradual solidification from b...

AI Technical Summary

Problems solved by technology

After electroslag remelting, the steel quality is pure, the structure is compact, and the composition is uniform. However, this series of steel electroslag ingots are prone to bursting, causing losses

[0003] In order to ensure the quality of 3Cr17NiMo series high-end plastic mold steel products, the product adopts the electroslag remelting process, but due to the following reasons, the electroslag ingots of this steel type are prone to bursting, resulting in losses: (1). The gradual solidification from bottom to top, and the cooling effect of the water-cooled crystallizer, lead to a large temperature difference between the two ends of the electroslag ingot, the surface, and the center after remelting. The larger the size of the electroslag ingot, the greater the temperature difference and the greater the thermal stress. (2) There is only the pearlite transformation start line in the C curve of this steel type, and there is no pearlite transformation end line, so the supercooled austenite of this steel cannot be completely transformed into pearlite, and there is a large amount of residual after cooling. Austenite, and the Mf (martensite transformation end temperature) point of the steel is low, and a large amount of retained austenite will undergo martensite transformation at room temperature, so it is difficult to completely remove the internal stress of the electroslag ingot by general annealing, resulting in bursting

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