The project “Development and Application of Complete Sets of Technologies for Key Materials for Metal Structures of Super Large Hydropower Stations”, led by Shougang Group, won the second prize of the National Science and Technology Progress Award. Zhou Deguang, deputy general manager and professor-level senior engineer of Jingtang Company, who participated in the 2018 National Science and Technology Awards Conference, led on January 8th as the award-winning representative and was received by General Secretary Xi Jinping.

The Shougang Hydropower Steel R&D Team has “smashed a sword for ten years”, growing into a leader of the “preferred steel” in China's hydropower project construction after starting from ““zero market share, zero application performance, and zero public praise from customers” 10 years ago.

By the end of 2018, Shougang Hydropower Steel had accumulated production and sales of 40,300 tons, achieving direct income of 73.82 million yuan and profit of more than 10 million yuan. At the same time, it will drive downstream construction and manufacturing enterprises to achieve revenue of 10.5 billion yuan and a total profit of 420 million yuan. The product specifications range from 10mm to 150mm in thickness, while the strength covers 500 MPa to 800 MPa. The company has become one of the few steel enterprises in China with a full range of hydropower steel production capacity. Its products have been successfully applied to 31 major hydropower projects at home and abroad, including Baihetan Hydropower Station, the Malaysian Murum Hydropower Station, and Xe-PianXe-Namnoy Hydropower Station in Laos along the “Belt and Road”. Among them, the domestic market share of 150mm extra-thick hydroelectric steel is 100%, now being substituted for all imported steel. 

After ten years of painstaking exploration and progress, Shougang has achieved great success in the research and development of steel for super large hydropower stations, reaching the international leading level in this field.

In October 2009, the Murum Hydropower Project in Malaysia, which was built by China Hydropower Construction Company, bid for 48 tons of 150 mm-thick steel plate. The construction of this power station required a total of nearly 17,000 tons of various steel plates, while the 150 mm steel plate required only 48 tons. The construction unit proposed that "whoever can overcome the difficulty of 150mm steel plate in China can get the order for all the steel materials needed for the power station."

This 48-ton order was four steel plates at best. Whoever could produce four steel plates that met the design standards would get an order for 17,000 tons of steel plates. Moreover, the winner could have a share in the hydropower steel market, which was a great temptation. However, after the bidding for the 48-ton 150mm high-strength and extra-thick steel plate was submitted to the domestic steel industry, no company dared to accept this "hot potato". At that time, the unknown Shouqin Company launched a heated discussion, and soon formed a consensus: Shouqin's product structure adjustment was imperative, and Shouqin Company determined to accept this "hot potato” to take the task of producing 150mm hydropower steel plates in China.

The first challenge in producing 150 mm high-strength and extra-thick steel plate was the compression ratio in rolling mill production. The compression ratio refers to the ratio of the stock thickness to the thickness of the rolled steel sheet. Different steel grades and products with different uses have different compression ratio requirements. The compression ratio of general structural steel is greater than 3-5 times, gear steel is 8-10 times, and bearing steel is 10-12 times. The greater the compression ratio, the better the low temperature toughness and thickness direction properties.

After the smelting, rolling, and other aspects fully met the process requirements, further improving the level of refinement of the internal structure of the steel sheet by heat treatment became the most critical part of improving performance. Therefore, from October 2009 to April 2010, the research team focused on the heat treatment process for more than six months, conducted more than ten rounds of industrial and laboratory heat treatment tests, and made detailed records and comparisons of organizational changes and performance changes in each process. 

In order to overcome the difficulties of heat treatment, the participants kept improving every link, from the parameter settings of technical indicators, to the stable operation of equipment operations, to the operation of front-line workers. In those days, working overtime became commonplace for everyone. During the Spring Festival of 2010, product trial production entered a critical period. The temperature in the Qinhuangdao area dropped to negative 20 degrees Celsius. At the production site, from the heat-burning furnace to the quenching machine that dripped into ice, a sample weighing 100 kilograms was moved in a repeated manner, and a large amount of data was obtained. Afterwards, the researchers of the Institute of Technology researched the spectrum analysis of the metallographic structure of the sample under the microscope day and night. Every photo, every data point, and every chart recorded everyone’s meticulous dedication.

The hard work paid off. After repeated experiments, optimization, and verification, the method of rolling a 150 mm thick steel plate with a continuous casting billet with a thickness of 320 mm was finally explored. For the first time in China, a 150 mm high-strength and thick hydroelectric crescent rib steel sheet was rolled out in a continuous casting billet, which broke the monopoly of foreign companies on this key material and filled the domestic gap.

The four steel plates were delivered on time and with quality, greatly improving the international influence of Shougang's hydroelectric steel, and firing the first shot of producing steel for super large hydropower stations.

After that, Shouqin Company spent four months in 2012 supplying 560 tons of steel plates for the GIBE Hydropower Station in Ethiopia. In 2015, it took two months to deliver 880 tons of steel plates for the Tarbela IV Hydropower Station in Pakistan, with a pass rate of 100%.

The 800MPa high-strength hydroelectric steel developed by Shouqin Company has a 22% reduction in welding sensitivity and a 56% reduction in preheating temperature compared with the same level of the international advanced company that produces high-strength steel. The heat input window increased by 25%. Shougang Technology Research Institute has developed 800MPa grade matching consumables, which outperform the world-recognized highest level in the field of welding consumables - the same kind of products from Kobe Steel Co., Ltd. in Japan, with a heat input of up to 50kJ/cm and a welding efficiency of 1.5 times. The hydrogen content of the seam is only 2.6ml/100g, which is the level after the dehydrogenation treatment of the same grade of Kobe at 250 °C for 2 hours, which greatly reduces the difficulty and cycle of construction on site.

For more than ten years, under the cooperation of Shouqin Company and Shougang Technology Research Institute, we have achieved a series of major breakthroughs in hydropower steel material design and development, key production technologies, key welding materials and application technologies, and developed complete sets of key materials for metal structures of super large hydropower stations, especially high-strength 800 MPa grade steel plates, 150 mm special thick plates, and matching welding consumables for high heat input and high-efficiency welding technology, reaching the international leading level.

The 150mm ultra-thick hydropower steel sheet produced by Shougang has a domestic market share of 100% and has been successfully applied to 31 major domestic and international major hydropower projects, 8 of which are located along the “Belt and Road”. Shougang hydropower steel has become a national calling card for Chinese manufacturing. The results of the development and application of the complete set of key materials for metal structures of super large hydropower stations led by Shougang will not only provide clean energy for the development of the national economy, improve the ecological environment, and promote regional economic coordination and sustainable development, but will also drive the upgrading of ocean projects, energy equipment, construction, and other fields, having broad prospects for promotion and application.