Metallurgical Science and Technology Award First Prize | Basic parts Special steel Long life mechanism, key technologies and product development
World Metal Guide
project award status: 2022 Metallurgical Science and Technology Award first prize;
Completed unit: Iron and Steel Research Institute Co., Ltd., Jiangyin Xingcheng Special Steel Co., Ltd. , Daye Special Steel Co., Ltd., Beijing Jiaotong University , Shijiazhuang Iron and Steel Co., Ltd. responsibilities Responsible for the company , Fushun Special Steel Co., Ltd. , Baowu Special Metallurgical Co., Ltd., Northeast Special Steel Group Co., Ltd., Beijing University of Science and Technology , Tsinghua University ;
Completed person: Su Jie, Qian Gang, Hui Weijun, Wang Maoqiu, Xu Xiaohong, Zhou Lixin, Bai Yun, Hao Yanying, Liu Zhenbao, Xu Le, Feng Guiping, Ji Yuzhong, Zhang Yongjian, Zheng Wenchao, He Xiaofei.
1 Research background and problems
Special steel is an important symbol of a strong steel country and one of the important symbols that reflect a country's degree of industrialization. Bearings, gears, fasteners, springs, shafts and other basic parts are the core components of Advanced Manufacturing Industry. They are large in quantity and wide in scope and play an important supporting role in the manufacturing industry. Their development trend is higher reliability, longer life and better environmental adaptability. At present, my country's basic parts and special steels used in general have a large gap with foreign advanced levels, resulting in large but not strong manufacturing. Advanced equipment in the automobile, machinery, aviation, new energy and other industries has not yet been fully localized, becoming an important bottleneck for the transformation and upgrading of the manufacturing industry of " Made in China 2025". Compared with developed countries in equipment manufacturing such as Japan and Germany, my country's basic parts have a large output of special steel, but its quality stability, processing and use performance are significantly different from the advanced level of foreign countries, resulting in low reliability, large life fluctuations, poor service environment adaptability, and inability to meet the needs of high-end equipment manufacturing. It is urgently necessary to carry out catching up in relevant basic theories, key common technologies and applications to meet the development needs of manufacturing transformation and upgrading.
In response to the above problems, Steel Research Institute and Xingcheng Special Steel and other units, with the support of the National Key R&D Plan "Special Steel and Application for Basic Parts in Advanced Manufacturing" projects, special steel for bearing steel, gear steel for advanced manufacturing, spring steel for , non-tempered steel for typical basic parts with large and wide surfaces, and carried out a series of key technologies, efficient test characterization technologies and product development research, to meet the needs of advanced equipment such as automobiles, aviation, machine tools, and new energy, lay the foundation for the localization of advanced equipment and the upgrading of manufacturing industries, thereby driving the upgrading of my country's special steel industry and enhancing the overall competitiveness of the basic materials industry.
2 Ideas and solutions to solve problems
This project focuses on the goal of improving the technology of basic parts in advanced manufacturing industry, selects special steel for typical basic parts with large and wide surfaces such as bearing steel, gear steel, non-tempered steel, fastener steel, spring steel, etc., and carries out basic research on the mechanism of longevity based on prominent issues such as improving quality stability and longevity, and breaks through a series of key common technologies such as quality stability and performance improvement, and efficient testing and evaluation. Based on the above work, we develop high-end varieties of special steel for basic parts to achieve high performance, high added value, green and efficient low-carbon production, help improve the overall competitiveness of my country's special steel industry for basic parts and meet the urgent needs of my country's high-end manufacturing industry.
First of all, there is a risk of hydrogen-induced delayed fracture when the basic parts such as are in service during production and processing and complex environments, which is one of the key bottlenecks that limit the further increase in strength and application of special steels in the basic parts. How to improve the anti-hydrogen embrittlement ability of materials through alloy composition and microstructure design is a key scientific issue in the field of steel.In this regard, this project combines first-principle calculation with advanced experimental characterization methods such as three-dimensional atomic probe chromatography technology to try to clarify the electron-atom mechanism of hydrogen trapping at the interface of different types of carbide phases, provide a theoretical basis for hydrogen trap design and hydrogen-resistant embrittlement material development, and conducts research on delayed fracture technology on this basis.
Secondly, advanced manufacturing basic parts not only require high strength, but also high safety and reliability. Given that fatigue damage is the main reason for the early failure of moving parts such as bearings, springs, gears, etc., in this regard, the influence of inclusions, tissue evolution and surface treatment on fatigue properties such as bearing steel, gear steel, spring steel and non-adjustable steel is studied in depth, and the long fatigue life technology of steel for basic parts and efficient fatigue performance evaluation technology is formed.
In response to the problems of homogeneity of special steel products for basic parts and low value, based on the above research work, a series of key common technologies such as high-clean smelting, large-particle brittle inclusions and sulfide control, high-uniformity solidification homogeneity control, heat treatment and surface modification, and low-cost manufacturing, to achieve stable production and application demonstration of special steel varieties for basic parts, and to develop a series of high-end varieties urgently needed by advanced manufacturing to meet the upgrade needs of high-end machine tools, offshore wind power , new energy vehicles, engineering machinery, aviation and other industries.
3 Main innovative achievements
1) developed a refining slag CaO activity prediction and control model and sulfide aspect ratio control technology coupled to sulfide denaturation and oxide metallurgy , solving the problem of controlling the aspect ratio of large-size brittle inclusions and sulfides.
established the " slag molecule-ionic system free CaO activity prediction and control model". Combined with online CaO activity control and tundra flow field control, the Ds inclusions of bearing steel can be stably controlled ≤0.5 levels. In the past three years, the pass rate of about 30,000 furnaces has reached 99%, and the contact fatigue life has been increased by 4 times. By controlling the precipitation temperature of oxide , uniform fine oxides are obtained as the core of sulfide nucleation, and combined with sulfide denaturation treatment, the problem of sulfide aspect ratio control is solved. The sulfide aspect ratio of non-tempered steel is ≤5, with an average value of 2.6.
2) developed tundra temperature control, water port reflux adjustment and other continuous casting light pressure homogenization technologies based on displacement control, solving problems such as carbon segregation stability of steel for basic parts.
developed a flow field-temperature field coupling model containing parameters such as the impact depth of the steel in the tundra impact area, and used online detection and dynamic induction heating replenishment, oversteer flow rate and water port reflux adjustment to achieve the overheat of the tundra 10-16℃; by optimizing the end liquid core model of the billet, accurate judgment of the solidification end, innovatively proposed a displacement control model, solving the problems of carbide carbide in the bearing steel, black center segregation of the spring steel and ultra-narrow hardenability bandwidth of the gear steel. The carbon difference in the cross-section of the gear steel is ≤0.02% and the pass rate of the hardenable belt ≤4HRC exceeds 97%, and the carbide carbide in the bearing steel is all 0.
3) has proposed the hydrogen trap design principle based on Bader atomic volume for the first time in the world, and developed a high-strength steel ultra-longevity technology based on nanocarbide hydrogen traps.
The interaction mechanism between alloy elements and hydrogen traps was studied from the atomic and electronic levels, and the hydrogen trap design principle based on the volume of Bader atoms was proposed; a new alloying idea for controlling the hydrogen evolution reaction of steel in service environment was proposed, which reduced the hydrogen content of diffusable atomic ; the mechanism of action of carburized layers and inclusions in the fatigue process was clarified, and a fatigue strength evaluation model of carburized steel comprehensively considered the influence of inclusions and carburized layers was established.
4) developed the bearing steel inclusion ultrasonic online detection technology and the fatigue limit measurement technology of non-tempered steel metallographic samples, realizing online detection and efficient evaluation.
developed ultrasonic equipment and data processing model, solved the problem that ultrasonic flaw detection cannot detect large particles, and realized online detection of macroscopic inclusions; invented hydrogen embrittlement stretching method for efficient detection of coarse inclusions in high/ultrapure steel; proposed ferrite strengthening and refining non-steel structure regulation technology, breaking through the fatigue limit technology of metallographic test measurement, and establishing the gap fatigue limit prediction model .
5) has developed a series of high-end varieties for long-life life, meeting the needs of high-end manufacturing industries such as new energy vehicles, offshore wind power, and aviation.
Invented 1400MPa grade high-strength bainite type non-adjustment steel, delay-resistant fracture-resistant high-strength steel for grade 12.9 wind power bolts and 2100MPa grade ultra-high-strength spring steel; developed LF furnace ultra-low sulfur, sulfide denaturation combined with vacuum self-consumption low melting speed deep degassing technology, replacing the traditional dual vacuum smelting process, forming a low-cost single vacuum smelting technology for aviation shaft steel, with a cost reduction of 30%.
4 Application situation and effects
A series of key technologies developed in this project to improve the quality stability and service life of steel for basic parts developed. Since 2017, Xingcheng Special Steel, Daye Special Steel, Baowu Special Steel and other enterprises have been widely used in the production of special steels such as bearing steel, gear steel, non-temperature steel, fastener steel, spring steel, shaft steel, etc. The output in the past three years is about 7.7 million tons, with an additional output value of 10.4 billion yuan, with huge economic benefits. The developed series of varieties are widely used in high-end equipment parts such as automobiles, engineering machinery, precision machine tools, , wind power, etc., meeting the urgent needs of downstream industries and promoting the upgrading of my country's manufacturing industry. At the same time, it is also exported in batches to foreign parts manufacturing companies such as bearings, gears, and automotive forgings, which significantly enhances the international competitiveness of my country's basic raw materials.
High-pure long-life bearing steel developed by Xingcheng Special Steel is a product of " China's famous brand ". It has now obtained the quality certification of global bearing manufacturers Swedish SKF, German SCHAEFFLER, Japanese NTN-SNR, NSK and other quality certifications and has been supplied in batches and stably for many years. It is the first China Steel company to obtain the "green channel" of SKF. The high-quality automotive gear steel (FAS3420H, 20MnCr5H, etc.) developed by Fugang has been successfully applied to gear transmissions such as high-end cars, heavy-duty commercial vehicles, etc. independently developed by my country, further promoting the localization of high-end cars and reducing the cost of high-end cars. Yegang and Shigang use innovative sulfide control and tissue performance control technology to develop more than 50 non-tempered steel varieties, with a cumulative production volume of about 650,000 tons in the past three years. They are widely used in the manufacturing of automobile engine crankshaft , connecting rods, wheel hubs, drive shaft and other automobile parts products, as well as hydraulic piston rods, semi-axles, tie rods and other engineering machinery products.
my country's special steel for basic parts with large and wide output of large and wide surfaces exceeds 10 million tons, with a huge industrial scale and an annual output value of more than 100 billion yuan. The results of this project play a good demonstration role, and can be promoted and applied to other related enterprises and above outside the project, and can drive the technological progress of the industry through standard revisions and other means; at the same time, the results of this project can also be promoted and applied to other special steel varieties such as mold steel , comprehensively improve the quality level and service performance of special steels, and strongly support the upgrading of my country's manufacturing industry. Therefore, the project results have very good promotion and application prospects. In addition, the project has obtained 35 national invention patents, formulated and revised 8 national standards and 2 industry standards, and published 78 academic papers, including 238 SCI papers and 3 EI papers.
▲ "World Metals Guide" Issue 37 B08
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