【作者】 李依依； 柯伟；

【Author】 LIYiyi,KE Wei (Institute of Metal Research,CAS.72 Wenhua Rd.,Shenyang 110016)

【机构】 中国科学院金属研究所；

【摘要】 三峡700MW级大型混流式水轮机转轮由上冠、下环和13-15片叶片组焊而成,重达400余吨,是目前世界上最大的水轮机转轮。上冠、下环和叶片材质均为ZG04Cr13Ni4Mo马氏体不锈钢。ZG0Cr13Ni4Mo马氏体不锈钢具有高强度、高韧性以及良好的焊接性能,其性能与微观组织、化学成分和热处理工艺密切相关。从韩国、日本、欧洲进口的三峡转轮铸件中焊接时有时出现裂纹,分析结果表明该钢中含有大量的δ-铁素体,降低了材料的塑性和韧性。同时,δ-铁素体也会在在腐蚀性的环境中易引起材料的破坏。为了实现水轮机转轮大型铸件的国产化,系统地开展了转轮用.ZG04Cr13Ni4Mo马氏体不锈钢的化学成分、显微组织、力学性能、铸造工艺与热处理工艺等关键工艺技术的研究,提出了通过优化化学成分和热处理工艺定量控制ZG04Cr13Ni4Mo马氏体不锈钢中高温δ铁素体和逆变奥氏体两种相,提高了材料的综合性能。在对铸件材料研究的基础上,结合计算机模拟,实现了三峡大型水轮机转轮叶片的近终形制造。水轮机转轮在水电站机组运行中会出现的新问题,如空蚀、腐蚀、磨损、疲劳断裂等。本文讨论了长运行周期大型铸件的前瞻性失效预测所面临的科学问题和挑战。更多还原

【Abstract】 Three Gorges 700MW hydraulic runner is the largest size in the world and its weight is more than 400 tons.It consists of the top crown and the lower ring through 13-15 blades which are welded together.Martensitic stainless steel ZG04Cr13Ni4Mo is used for hydraulic turbine runner due to its high strength,superior impact toughness and excellent weldability,but its properties are very sensitive to the variation in microstructure and chemical composition as well as heat treatment processing.Some rough castings imported from Korea,Japan and European were generating crack while welding.It was found a large number of delta ferrite in the steel.The greater the amount of delta ferrite,the lower the weld metal ductility and toughness.Delta ferrite is also preferentially attacked in a few corrosive environments. In order to produce qualified turbine runner casting with domestic advanced technology,we have carried out the research for the materials and processing technology.Quantitatively control of two phases,delta ferrite and reversed austenite,chemical composition optimization and heat treatment is proposed to decrease the tensile strength and to increase the ductility and impact energy of ZG04Cr13Ni4Mo steel.Combining the computer simulation,this study puts the above research results into the hydraulic turbine runner blade producing and achieves the near-net-shape manufacture of the blade. It is important to pay more attention to cavitation damage,corrosion,fatigue,wear and tear,during operation of the hydraulic turbine runner.Proactivity in predicting failures and prevention is emphasized for such a large scale casting.更多还原