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一、问题的提出在六十年代末七十年代初,欧、美、日工业发达国家开始研制和发展可控硅中频装置不久,我们也投入了研制和应用可控硅中频技术的工作,首先是在熔炼方面。 1973年我国开始安装三十万千瓦的大型发电机组,电站合金管道焊接时,为使其焊缝强度不低于母体的强度和防止由于热应力而产生脆裂,必须在焊前预热和焊后按照一定的工艺要求进行热处理。过去是采用火焊烤,电阻炉辐射加热和采用工频电源感应加热等方法。这些方法已很难适应大型机组的施工,例如对于30万千瓦机组上大量采用的φ365×40,φ426×
First, the issue raised In the late sixties and early seventies, Europe, the United States, Japan and other industrialized countries began to develop and develop SCR intermediate frequency device soon, we have also invested in the development and application of SCR intermediate frequency technology work, first of all It is melting. In 1973 China began to install three hundred thousand kilowatts of large generating units, power plant alloy pipe welding, in order to make the weld strength of not less than the strength of the mother and to prevent the occurrence of brittleness due to thermal stress, must be preheated and welded before welding After a certain process requirements for heat treatment. The past is the use of fire welding roasted, resistance furnace radiation heating and power frequency induction heating and other methods. These methods have been very difficult to adapt to the construction of large units, for example, for a large number of φ365 × 40, φ426 ×