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在焊补耐热珠光体钢电站设备大型铸件缺陷时,为避免焊接裂纹和改善补焊区性能,通常采用与基材相同类型的焊条,焊前进行予热焊后进行650—720℃的高温热处理。但这种工艺措施十分复杂,并且往往导致经过加工的高精度电站设备铸件变形过大,超出这些铸件装配时的允许要求。本文在分析补焊高精度耐热珠光体钢铸件困难、奥氏体与非奥氏体钢焊接接头特性以及我国电站设备运行条件的基础上,利用铁基奥氏体钢焊条对ZG20CrMOV钢进行了焊接试验,并对全国10多个电站汽轮机的汽缸和主汽阀等大型铸件的缺陷,采取千斤顶增大刚性控制变形和焊后不进行热处理等措施进行了焊补,焊后变形和焊补区的质量均达到理想要求,并经长达10万小时以上的高温高压下实际工作的考验,检查证明焊补区的质量一般仍然良好为电站设备铸件精加工后发现的缺陷焊补,尤其为电站现场补焊提供了一种工艺简便,劳动强度低,修理周期短,容易控制变形和质量可靠的方法。
In the welding of refractory pearlite steel plant equipment, large castings defects, in order to avoid welding cracks and improve the properties of the welding zone, usually with the substrate of the same type of electrode before welding preheat welding 650-720 ℃ high temperature Heat treatment. However, this process is complicated and often leads to excessive deformation of the machined high-precision power plant equipment castings that exceed the allowable requirements for the assembly of these castings. In this paper, based on the analysis of the difficulty of welding high-precision heat-resistant pearlite steel castings, the characteristics of welded joints of austenitic and non-austenitic steels and the operating conditions of power station equipment in China, ZG20CrMOV steel was treated with iron-based austenitic steel electrodes Welding test and steam turbine over the country more than 10 power stations and main steam valve and other large castings defects, to increase the rigidity of the jack control deformation and welding without heat treatment measures such as welding repair, welding deformation and welding repair area Of the quality to meet the desired requirements, and after more than 100,000 hours under the high temperature and pressure test the actual work, inspection and certification of the quality of the welding area is still generally good for power plant equipment casting found defects after welding, especially for power plants On-site welding provides a simple process, low labor intensity, repair cycle is short, easy to control deformation and reliable quality methods.