Non-oxidizing normalizing process of steel pipe and device

Abstract

The invention relates to a non-oxidizing normalizing process of a steel pipe. The non-oxidizing normalizing process of the steel pipe is characterized by comprising the following steps of S1, pretreatment which comprises the following sub-steps of S11, preheating and heating; and S12, heat preserving, specifically, a conveying mechanism continues to convey the steel pipe forwards to a heat preserving area, the heat preserving temperature is 850-900 DEG C, and the heat preserving time is 6-8 min; S2, air cooling, specifically, nitrogen is fed into an air cooling area through a nitrogen station,the nitrogen is used as media, and used for fast cooling the steel pipe, and the steel pipe is cooled to 350-400 DEG C within the time of 1.5-2 min; S3, water cooling, specifically, a water cooling area is divided into three segments, the temperature rebounding of the steel pipe is 150-200 DEG C in the first segment of the water cooling area, that is, the temperature of the steel pipe is made tobe 500-600 DEG ; and in the first segment of the water cooling area and the second segment of the water cooling area, the steel pipe is gradually cooled to be 200 DEG C or below; and S4, discharging out of a furnace, air cooling is performed till a room temperature is achieved. The invention further discloses a device used for the non-oxidizing normalizing process of the steel pipe. Due to the non-oxidizing normalizing process of the steel pipe, the cooling speed is effectively controlled, the ideal hardness, organization and surface quality are achieved, cost is lowered, and the on-time delivery rate is increased.

Description

technical field

[0001] The invention relates to the technical field of steel pipe heat treatment, in particular to a steel pipe non-oxidation normalizing process and device. Background technique

[0002] Competitive steel pipes in today's market have a hardness of HB190-240, inner and outer decarburized layers within 0.03mm, fully decarburized layers within 0.05mm, and no scale on the surface. The traditional normalizing process adopts ordinary heat treatment furnace normalizing + fog Cold, the decarburization layer cannot be guaranteed, the surface oxide scale is serious, and the hardness is unstable, between HB160-190. Even if the hardness is barely qualified, three additional processes are required: ① Pickling the surface of the product to remove scale; ② Polishing the outer surface of the product; ③ Honing the inner surface of the product. To obtain the decarburized layer required by customers, the cost is 1,000-1,500 yuan / ton, and the delivery time is relatively long, ...

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