Steel casting heat treatment technology

A steel casting, quenching and tempering heat treatment technology, applied in the field of heat treatment technology, can solve the problems of waste of resources, production costs, unsatisfactory heat treatment, and low product qualification rate

Inactive Publication Date: 2016-06-29
CHONGQING YONGLIN MACHINERY EQUIP
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Problems solved by technology

As customers have higher and higher quality requirements, the casting process needs to be continuously improved and improved. However, the heat treatment of the

Method used

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Embodiment Construction

[0007] The present invention will be further described below in conjunction with embodiment:

[0008] A heat treatment process for steel castings. The material is ZG25CrNiMo. It follows the following process steps: After the casting is completed, the castings are subjected to a high-temperature normalizing at 940-950°C for 12 hours, and then they are air-cooled after being released from the furnace, and the grains are refined for the second time. Heat at 880-900°C, keep warm for 10 hours, then take out of the furnace and air-cool, and carry out machining. After the rough machining inspection is qualified, it needs to be quenched and tempered. The heat treatment of quenching and tempering is quenching at 850±10°C. Water quenching; then tempered at 670°C, held for 7 hours, and then out of the furnace and air-cooled. After quenching and tempering heat treatment, the mechanical properties of the castings reached: σ0.2≥520MPa, σb≥655MPa, ψ≥35%, δ≥18 %, surface hardness HB220-250. ...

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Abstract

The invention discloses a steel casting heat treatment technology. The technology utilizes ZG25CrNiMo and is characterized by comprising carrying out primary high-temperature normalization on a casting at a temperature of 940-950 DEG C after casting, carrying out thermal insulation for 10-12h, discharging the casting out of a furnace, carrying out air cooling, carrying out secondary grain refinement normalization at a temperature of 880-900 DEG C, carrying out thermal insulation for 8-10h, carrying out hardening and tempering heat treatment after the casting passes through rough machining inspection, wherein the hardening and tempering heat treatment process comprises hardening at a temperature of 850+/-10 DEG C, thermal insulation for 6-8h, tempering at a temperature of 660-680 DEG C and thermal insulation for 6-9h, and carrying out discharging and air cooling. The steel casting heat treatment technology can eliminate thermal stress through heat treatment after casting, improves machinability and reduces processing deformation. Heat treatment after rough machining improves general mechanical performances of a product and prolongs a service life.

Description

technical field [0001] The invention belongs to the field of heat treatment technology, in particular to a heat treatment technology for steel castings. Background technique [0002] ZG25CrNiMo steel castings are usually heat treated after casting. Because the grains of the castings before heat treatment are coarse, the structure direction is obvious, and the mechanical properties are low, the heat treatment process is formulated according to the different requirements of the castings. Its ZG25CrNiMo chemical composition is (%): C0.26-0.30, Si0.20-0.35, Mn0.80-1.00, Cr0.60-1.00, Ni0.50-0.95, Mo0.20-0.30, Cu≤0.18, P ≤0.025, S≤0.025. Generally, steel castings are required to be annealed, softened and easy to process; in addition, those that require strength must be normalized, and those that require hardness must be quenched. As customers have higher and higher quality requirements, the casting process needs to be continuously improved and improved. However, the existing ca...

Claims

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Application Information

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IPC IPC(8): C21D1/28C21D1/25C21D6/00
Inventor 毛永林
Owner CHONGQING YONGLIN MACHINERY EQUIP
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