Quick spheroidal annealing thermal treatment process for Cr12 extruded seamless steel tube

A technology for annealing heat treatment and seamless steel pipes, applied in heat treatment furnaces, heat treatment equipment, manufacturing tools, etc., can solve the problems of low production efficiency and achieve the effect of shortening the time of spheroidizing annealing process

Inactive Publication Date: 2016-07-13
HANDAN XINXING SPECIAL TUBING CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] When the heat treatment of Cr12 extruded seamless steel pipe is carried out according to the above process, the process time reaches more than 40 hours. Due to the limitation of the heat treatment furnace type, only periodic heat treatment furnaces can be used, and quenching oil or quenching liquid is also required, and the production efficiency is low.

Method used

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  • Quick spheroidal annealing thermal treatment process for Cr12 extruded seamless steel tube
  • Quick spheroidal annealing thermal treatment process for Cr12 extruded seamless steel tube

Examples

Experimental program
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Effect test

Embodiment 1

[0021] Continuous heat treatment furnace is adopted, and the spheroidizing annealing process curve is shown in the attachment figure 1 . Cr12 extruded billet size: outer diameter Ф300mm, inner diameter Ф45mm, length 520mm, extruded seamless pipe size is outer diameter Ф196mm, thickness 12mm.

[0022] After extrusion, the temperature of the steel pipe is above 1000°C, air-cooled to 350-450°C, and put into the furnace for spheroidizing annealing. The temperature in the furnace section is 600°C, which plays the role of slow heating. ℃, keep warm for 1~2h, the slow cooling section I is longer, the temperature is controlled in 4 sections, the temperature is 690~710℃, 660~680℃, 630~650℃, 600~620℃, and the temperature drop is guaranteed to be ≤30℃ / h, the slow cooling section II is divided into two sections of temperature control, one section with a temperature of 570°C, and the other section with a temperature of 500°C, and the furnace is air-cooled. The hardness is 230-260HB, whi...

Embodiment 2

[0024] Periodic heat treatment furnace is adopted, and the spheroidizing annealing process curve is shown in the appendix figure 2 . Due to the fast pace of extrusion production and the slow pace of continuous heat treatment furnace, the above-mentioned Cr12 extruded seamless pipes are air-cooled to 400°C and slowly cooled in a slow cooling pit. During heat treatment, the furnace temperature is 400°C (it can also be put into the furnace at room temperature, the temperature of the front furnace is 500°C, and the furnace temperature is about 400°C after the furnace is discharged and loaded), and the heating rate is controlled at 100°C / h. At 740-720°C, keep warm 1~2h, cooling according to the above-mentioned two-stage cooling rate, cooling down to 600~620°C at a cooling rate of ≤30°C / h, and then adopting furnace cooling, and air cooling when the furnace temperature is not higher than 500°C. The hardness is 220-250HB. It can be seen that the hardness of periodic spheroidizing an...

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Abstract

The invention discloses a quick spheroidal annealing thermal treatment process for a Cr12 extruded seamless steel tube, and a high-temperature annealing heating process and a cooling process are saved. The quick spheroidal annealing thermal treatment process is characterized in that the extruded seamless steel tube is air-cooled to a temperature of 350-450 DEG C to directly enter a furnace for spheroidal annealing, or is slowly cooled to enter the furnace for spheroidal annealing; the extruded seamless tube is slowly heated to a temperature of 720-740 DEG C, the heat is preserved for 1-2 hours, and the extruded seamless tube is cooled to a temperature of 600-620 DEG C with a speed being lower than or equal to 30 DEG C/h, is furnace-cooled to a temperature not exceeding 500 DEG C, and is then discharged out of the furnace for being air-cooled; the hardness HB is 220-260 after spheroidal annealing, so that the mechanical cutting processing requirements can be met; and the spheroidal annealing process time is shortened to 8-12 hours from original 40 hours, so that the spheroidal processing process time is greatly shortened, the production cost is reduced, and mass industrial production is realized.

Description

technical field [0001] The invention relates to a relatively large range, in particular to a rapid spheroidizing annealing heat treatment process for Cr12 extruded seamless steel pipes. Background technique [0002] Spheroidizing annealing is mainly a conventional heat treatment for high-carbon steel or high-carbon alloy steel, in order to reduce the hardness for easy processing, or as a preliminary heat treatment for final heat treatment. In September 1991, "300 Heat Treatment Processes" published by Machinery Industry Press for the fifth time, spheroidizing annealing was divided into one-time spheroidizing annealing, isothermal spheroidizing annealing, reciprocating spheroidizing annealing, and normalizing spheroidizing annealing. [0003] The composition of Cr12 in GB / T1299-2000 "Alloy Tool Steel" is: 2.00-2.30%C, ≤0.4%Si, ≤0.4%Mn, ≤0.035%P, ≤0.035%S, 11.50-13.00%Cr. It can be seen that Cr12 is a high-carbon and high-chromium material. It is a cold-working die steel. It ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/32C21D6/00C21D9/08
CPCC21D1/32C21D6/002C21D6/005C21D6/008C21D9/08
Inventor 武贤
Owner HANDAN XINXING SPECIAL TUBING CO LTD
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