Low Temperature Seamless Steel Tube Steelmaking Process Control Measures

First, control the C content. Matching the electric furnace with refining is an effective means to achieve precise control of the C content. Strictly control the C content at the end of the electric furnace smelting. The refining outside the furnace is carried out on the VD or RH furnace by increasing the argon flow rate and the diameter of the dip tube and the oxygen blowing method. Remove C to ensure the exact C content of pipeline steel.

Second, reduce the P and S content. By using high-quality scrap steel and appropriate refining slag to meet the needs of de-S, the high-alkali slag is made by electric furnace and the slag is strictly controlled to reduce the P content in the steel.

Third, to ensure the Ca content and weak agitation time in the steel, to strengthen the connection management between the continuous casting and the upper and lower heat, and to protect the pouring, can effectively reduce non-metallic inclusions in the steel.

Rolling process control. Since the specifications of the low-temperature seamless steel pipe purchased by the customer are?60?720 mm×4?10 mm, the geometrical accuracy of the thinner wall product will directly affect the welding quality and construction efficiency of the customer at the construction site, so PQF continuous rolling is adopted. The tube unit performs rolling, and adjusts the heating temperature and time of the tube blank, reduces the eccentricity of the perforation process, and reduces the uneven wall thickness.

Heat treatment process control. The heat treatment of the seamless steel tube is established within a reasonable temperature range, which is determined by the curve of the steel. The steel grade of the design was subjected to austenitizing at 840 °C and the test curve was kept for 3 minutes. The relationship between the cooling rate and the metallographic structure was observed to determine the heat treatment process during production.

According to the curve and equipment conditions of the steel, the low temperature seamless steel pipe is preferably subjected to normalizing or quenching and tempering, so that the production of the structure is relatively easy. Since the specification includes?60 mm×4 mm slender pipe, if the water quenching and tempering process is used, it is prone to bending, so it is more suitable to use normalizing or normalizing + tempering.

The heat treatment of low temperature seamless steel pipe needs to consider the heating speed and the heat preservation time, avoid the burning of steel pipe and the generation of iron oxide scale, and control the austenite grain size to improve the toughness matching and corrosion resistance of the steel pipe.

The low temperature seamless steel pipe has the following characteristics: 1. Wide range of sizes, outer diameter can be from 60 mm to 720 mm; 2. Good low temperature toughness and corrosion resistance, and can pass the strict corrosion resistance evaluation test; 3. The bent pipe is subjected to heat treatment after bending, and the performance of the bent pipe is improved.

A worker from a steel pipe company, which is located in China.