Heat treatment method for improving low-temperature toughness of WC6-1.7357 material

Abstract

The invention discloses a heat treatment method for improving the low-temperature toughness of a WC6-1.7357 material. The method comprises the following steps of placing a casting and a test block in a heat treatment furnace, gradually raising the temperature of the heat treatment furnace at speed which is controlled to be less than or equal to 120 DEG C per hour, stopping raising the temperature when the temperature of the heat treatment furnace reaches 940+/-10 DEG C, and keeping the temperature of the heat treatment furnace within the range of 940+/-10 DEG C; after the casting and the test block are naturally cooled to 860+/-10 DEG C along with the heat treatment furnace after heat preservation, preserving heat for 0.5 hour, taking the casting and the test block out of the heat treatment furnace, and placing the casting and the test block in a still pool for cooling, wherein the temperature of water is ranged from 30 to 55 DEG C; placing the casting and the test block in the heat treatment furnace again for treatment within 2 hours after the steps are finished, gradually raising the temperature of the heat treatment furnace at speed which is controlled to be less than or equal to 100 DEG C per hour, preserving the heat when the temperature of the heat treatment furnace reaches 720+/-10 DEG C, and removing the casting and the test block out of the heat treatment furnace for air cooling.

Description

Technical field: [0001] The process method relates to a heat treatment process for alloy steel castings for high-temperature pressure-bearing parts, specifically an alloy steel for high-temperature pressure-bearing parts, which needs to meet the performance requirements of low-temperature steel. The alloy steel (WC6-1.7357) applicable to the present invention is, in terms of element mass percentage, carbon: 0.15-0.20, manganese: 0.50-0.80, silicon: ≤0.60; phosphorus: ≤0.020, sulfur: ≤0.020, chromium: 1.00-1.50; molybdenum: 0.45-0.65, nickel ≤0.50, copper ≤0.50, vanadium ≤0.05, tungsten ≤0.10, other elements are omitted. Background technique: [0002] At present, castings made of WC6-1.7357 have been double-certified by some foreign customers (such as: French SRI, Germany Sanpu, etc.). This material originally meets the performance requirements of high-temperature alloy steel, but now customers have to meet the performance requirements of low-temperature steel. ;The original...

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Problems solved by technology

[0002] At present, castings made of WC6-1.7357 have been double-certified by some foreign customers (such as: SRI in France, Sanpu in Germany, etc.). This material originally meets the performance requirements of high-temperature alloy steel, but now customers have to meet the performance requirements of low-temperature steel. ; The original casting heat treatment normalizing + tempering process can no longer meet the customer's requirements for low-temperature impact on the material. If it fails to meet the low-temperature impact performance requirements, the customer's order will be lost, which will bring economic and reputation losses to the group. loss

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