A kind of 25mn steel flange casting forming, quenching, tempering strengthening and toughening treatment method

Abstract

The invention discloses a 25Mn steel flange part casting-rolling forming and quenching-tempering strengthening and toughening treatment method, and belongs to the field of flange part machining and manufacturing. The method is characterized by comprising the steps that 1, centrifugal casting is carried out, wherein the casting temperature is 1520-1530 DEG C, the casting speed is 27-29 kg / s, and mold stripping is carried out after the surface temperature of an annular blank is decreased to 1060-1080 DEG C; 3, hot ring rolling is carried out, wherein ring rolling is started when the surface temperature of the ring blank is decreased to 1130+ / -10 DEG C, the ring rolling ratio gamma is equal to 2.5-3.5, the ratio delta of the wall thickness reduction amount to the height reduction amount is 0.7-0.9, and final rolling temperature is controlled to be 830+ / -10 DEG C; 4, quenching is carried out, wherein a flange part is subjected to air cooling to 550+ / -10 DEG C and then placed into a 12-15% NaCl water solution to be cooled, and the cooling time is t2; 5, tempering is carried out, wherein preheating is carried out at 500+ / -10 DEG C for 30 min, then, the flange part is heated to 590+ / -5 DEG C and kept at the temperature for the time t3, and the flange part is discharge out of a furnace and air-cooled to room temperature; and 6, the inner layer, the middle layer and the outer layer of the radial wall thickness of the flange part are sampled, the structure is observed, and the mechanical property is detected. The 25Mn steel flange part casting-rolling forming and quenching-tempering strengthening and toughening treatment method has the advantages that the strength and toughness of the flange part are improved, the technological process is shortened, and the production cost is saved.

Description

technical field [0001] The invention belongs to the field of processing and manufacturing of flange parts, and in particular relates to a 25Mn steel flange part casting and rolling forming and quenching and tempering strengthening and toughening treatment method. Background technique [0002] The wind power flange is a part of the wind power generation equipment. It is specially used for connecting fasteners between the towers. The general diameter ranges from 2 meters to 5 meters. High requirements, especially the resistance to cold and brittleness at low temperature, require the impact absorption energy to be greater than 27J. At present, the manufacturing process of wind power flanges is: bar blanking-heating-upsetting-punching-flat end face-heating-rolling-air cooling-heating-normalizing-air cooling-heating-tempering-air cooling, the process is lengthy , Repeated heating causes waste of time, materials and energy, serious oxidation and burning of materials, and the micr...

AI Technical Summary

Problems solved by technology

At present, the manufacturing process of wind power flanges is: bar blanking-heating-upsetting-punching-flat end face-heating-rolling-air cooling-heating-normalizing-air cooling-heating-tempering-air cooling, the process is lengthy , Repeated heating causes waste of time, materials and energy, serious oxidation and burning of materials, and the microstructure of wind power flange parts is sensitive to normalizing temperature, and it is easy to form Widmanstatten structure, which affects the precipitation of carbides and distribution, and directly lead to the reduction of the strength and toughness index of the flange ring

In addition, the patent application number "201210437446.1" discloses a method for compound strengthening of medium-carbon alloy steel bearing rings by rolling deformation quenching. )-hot rolling-quenching-high temperature tempering, the quenching after hot rolling refers to cooling the rings whose temperature is controlled at 860-950°C after hot rolling to 850°C, and then put them into a quenching pool with a water temperature of 50°C for cooling 2 to 15 minutes. The disadvantage of this process is that the grains grow due to static or sub-dynamic recrystallization during the cooling process after hot rolling, and when water is used as the quenching medium, it is easy to harden hard and initiate macro / micro cracks. Although the strength is high, the tempering holding time is inaccurate, which leads to the inability to guarantee the toughness; in addition, the material waste and oxidation loss in the process of forging blanks are serious, and the production efficiency is reduced

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