阅读说明：本技术 一种螺旋焊管q235-w钢种退火工艺 (Annealing process for Q235-W steel grade of spiral welded pipe ) 是由 徐建生 曹捷 向华 于 2021-06-24 设计创作，主要内容包括：本发明公开了一种螺旋焊管Q235-W钢种退火工艺,用全氮气模式罩式炉退火,再结晶保温温度给定至680℃,出炉温度控制在280℃,让钢板充分氧化,在带钢两侧形成宽度月400㎜的致密氧化膜Fe-3O-4,中部形成稀薄氧化膜,防止带钢在后续发生氧化；温度曲线按照工艺曲线正常设置；将气氛曲线时间设定值全部改为0；将气氛曲线温度末段设定值全部改为出炉温度280℃；将气氛曲线气氛种类全部改为0；将气氛曲线气氛流量改为0h/m3。(The invention discloses a Q235-W steel grade annealing process for a spiral welded pipe, which comprises the steps of annealing by using a full-nitrogen mode bell-type furnace, setting the recrystallization heat preservation temperature to 680 ℃, controlling the tapping temperature to 280 ℃, fully oxidizing a steel plate, and forming compact oxide films Fe with the width of 400 mm on two sides of strip steel 3 O 4 A thin oxide film is formed in the middle part to prevent the strip steel from being oxidized subsequently; the temperature curve is normally set according to the process curve; changing the time set value of the atmosphere curve into 0; changing the set value of the end temperature of the atmosphere curve into the tapping temperature of 280 ℃; changing the atmosphere types of the atmosphere curve into 0; and changing the atmosphere flow of the atmosphere curve to 0h/m for carrying out the high-speed thin film cultivation.)

1. The annealing process of the Q235-W steel grade of the spiral welded pipe is characterized in that a full-nitrogen mode bell-type furnace is used for annealing, the recrystallization heat preservation temperature is set to 680 ℃, the tapping temperature is controlled to 280 ℃, the steel plate is fully oxidized, and dense oxidation films Fe with the width of 400 mm per month are formed on two sides of the strip steel₃O₄A thin oxide film is formed in the middle part to prevent the strip steel from being oxidized subsequently; the temperature curve is normally set according to the process curve; changing the time set value of the atmosphere curve into 0; changing the set value of the end temperature of the atmosphere curve into the tapping temperature of 280 ℃; changing the atmosphere types of the atmosphere curve into 0; and changing the atmosphere flow of the atmosphere curve to 0h/m for carrying out the high-speed thin film cultivation.

Technical Field

The invention relates to an annealing process for a Q235-W steel grade of a spiral welded pipe.

Background

Low carbon steel has excellent weldability, good toughness and suitable strength characteristics, and is widely used in welded pipes. The steel for the Q235B carbon component can meet the structural requirements of common components and is economical and practical. The heating pipeline for town heating is a spiral steel pipe made of Q235B steel. When steel is rolled into steel pipe, there are gaps and welding is required. Due to uneven and large thickness (the maximum thickness fluctuation reaches 70 mu m), in the welding process of the common hot rolled plate, cold joint or welding line cracking occurs, and the welding quality and the service life are seriously influenced.

Disclosure of Invention

The invention aims to provide an annealing process for a Q235-W steel grade of a spiral welded pipe, which can further reduce the defect of uneven thickness, and ensure that the surface of strip steel is smooth and flat and the dimensional precision is improved.

The technical scheme adopted by the invention is as follows: an annealing process for a Q235-W steel grade of a spiral welded pipe comprises the steps of annealing by using a full-nitrogen mode bell-type furnace, setting the recrystallization heat preservation temperature to 680 ℃, controlling the tapping temperature to 280 ℃, fully oxidizing a steel plate, and forming compact oxide films Fe with the width of 400 mm on two sides of strip steel₃O₄A thin oxide film is formed in the middle part to prevent the strip steel from being oxidized subsequently; the temperature curve is normally set according to the process curve; changing the time set value of the atmosphere curve into 0; changing the set value of the end temperature of the atmosphere curve into the tapping temperature of 280 ℃; changing the atmosphere types of the atmosphere curve into 0; and changing the atmosphere flow of the atmosphere curve to 0h/m for carrying out the high-speed thin film cultivation.

The cold-rolled steel plate is used for replacing the steel plate, the thickness fluctuation is reduced to be less than 20 mu m, and meanwhile, the steel plate has the advantages of smooth and flat surface, high dimensional precision, good mechanical property and the like. Meanwhile, the common cold-rolled sheet is annealed in a hydrogen mode, and the corrosion speed is high when the surface of the steel sheet is not coated with oil, so that the welding quality and the surface quality are also influenced. Annealing in a full nitrogen mode bell-type furnace, setting the recrystallization heat preservation temperature to 680 ℃, controlling the tapping temperature to 280 ℃, fully oxidizing the steel plate, and forming compact oxide films (Fe) with the width of 400 mm on two sides of the strip steel₃O₄) And a thin oxide film is formed in the middle part to prevent the strip steel from being oxidized subsequently. The invention accelerates the welding speed by 1.5 times through the actual operation and use on site, and improves the welding quality to the highest value of history.

The specific implementation mode is as follows:

an annealing process for a Q235-W steel grade of a spiral welded pipe comprises the steps of annealing by using a full-nitrogen mode bell-type furnace, setting the recrystallization heat preservation temperature to 680 ℃, controlling the tapping temperature to 280 ℃, fully oxidizing a steel plate, and forming compact oxide films Fe with the width of 400 mm on two sides of strip steel₃O₄A thin oxide film is formed in the middle part to prevent the strip steel from being oxidized subsequently; the temperature curve is normally set according to the process curve;changing the time set value of the atmosphere curve into 0; changing the set value of the end temperature of the atmosphere curve into the tapping temperature of 280 ℃; changing the atmosphere types of the atmosphere curve into 0; and changing the atmosphere flow of the atmosphere curve to 0h/m for carrying out the high-speed thin film cultivation.