Straight seam steel pipe rolling technology

1) Increase the hot charging temperature and hot charging ratio
Increasing the hot charging temperature and hot charging ratio is an important measure for energy conservation and emission reduction, which has attracted much attention. At present, the average hot charging temperature in my country is 500-600 °C, and the highest is 900 °C; the average hot charging ratio is 40%, and the production line reaches more than 75%. Nippon Steel Pipe's Fukuyama Plant's 1780mm hot-rolling mill has a hot charging rate of 65%, a direct rolling rate of 30%, and a hot-charging temperature of 1000°C; Sumitomo Kashima Plant's 1780mm hot-rolling mill has a direct rolling rate of 57%, and the hot charging temperature is greater than 850°C. , the hot charging rate is 28%. In the future, my country should increase the hot charging ratio of continuous casting slabs above 650 ℃, and strive to save energy by 25% to 35%.

2) Various heating technologies of the heating furnace
The heating technology includes regenerative heating, automatic combustion control, combustion of low calorific value fuel, low oxidation or no oxidation heating technology, etc. According to statistics, more than 330 steel rolling heating furnaces in my country have adopted regenerative combustion technology, and the energy saving effect can reach 20% to 35%. Energy consumption can be further reduced by optimizing combustion. This requires work on the use of low calorific value fuels and increasing the application of blast furnace gas and converter gas. The low-oxidation heating technology to achieve atmosphere control and the non-oxidation heating technology for gas protection are important measures to reduce oxidative burn loss and improve yield. The technology even eliminates the need for pickling. At present, the oxide scale produced by the heating process of steel rolling is 3-3.5kg/t, and the annual loss is estimated to be about 1.5 million t of steel (about 7.5 billion yuan). According to European scholars, the cost of pickling is 15-20 euros / t, if it can reduce the consumption of pickling and acid, it will have a significant effect on protecting the environment and reducing the pressure of waste acid treatment.

3) Low temperature rolling and rolling lubrication technology
Some domestic high-speed line manufacturers have adopted the low-temperature rolling process, and the average release temperature has reached 950 °C, and the low has dropped to 910 °C. . The total energy consumption of low-temperature rolling is about 10% to 15% lower than that of conventional rolling. According to the statistics of the Hot Rolling Plant of Kashima Steel Works in Japan, reducing the billet by 8°C will save energy by 4.2kJ/t, and the energy saving effect is 0.057%. However, low-temperature rolling has strict requirements on the uniformity of the heating temperature of the billet. The rolling lubrication technology can reduce the rolling force by 10% to 30%, reduce the power consumption by 5% to 10%, and reduce the iron oxide scale by about 1kg/t, thereby increasing the yield by 0.5% to 1.0%, and reducing the acidity of pickling. The consumption is about 0.3～1.0kg/t. Several domestic rolling mills have successfully applied to the production of stainless steel and electrical steel, with good results. In the future, while vigorously promoting rolling lubrication, we should strengthen the environmental protection of rolling lubrication medium, lubrication technology, and recycling technology.

4) Controlled rolling and controlled cooling technology and its equipment
Controlled rolling and controlled cooling technology are indispensable means of energy saving and material saving, high-performance products, and production. Representative steel materials such as DP steel, TRIP steel, TWIP steel, CP steel, AHSS steel, UHSS steel, other pipeline steel, building structural steel, grain steel, and heat-free steel are all produced by controlled rolling and controlled cooling technology. In addition to the new development of physical metallurgy as its technical basis, the controlled rolling and controlled cooling technology also benefit from new technologies and equipment, such as powerful rolling mills that can realize low temperature and high pressure, ultra-compact layout of rolling mills, ultra-rapid cooling ( UltraFastCooling), -Online accelerated cooling (Super-OLAC) device, reducing and sizing machine equipment, etc. In the future, the development of controlled rolling and controlled cooling technology will strongly depend on new technology and equipment. This is an important feature of the development of controlled rolling and controlled cooling technology, which needs to be paid attention to.