二次再热汽轮机高Si-Mo球铁中压外缸的生产

介绍了中压外缸上部铸件的结构及技术要求,详细阐述了该铸件的生产工艺:(1)产品整体放在上箱,下箱无产品结构,主要放置浇注系统和芯头定位;(2)采用开放式浇注系统,从法兰底面进铁液;(3)在最后凝固的部位放置冒口,使铸件趋于顺序凝固;(4)采用Si-Mg合金和重RE球化剂,球化剂上覆盖Si-Ba孕育剂,出铁3/4时随流加入Si-Ba孕育剂,浇注时随铁液添加Si-Ba孕育剂进行二次孕育;(5)铁液过热温度1 500～1 510℃,出铁温度控制在1 440～1 450℃,浇注温度1 320～1 330℃,浇注时间120 s。生产结果显示:铸件尺寸、NDT及力学性能检验结果均合格。

Production of High Si-Mo Nodular Iron Medium Pressure Outer Cylinder for Secondary Reheat Steam Turbine

The structure and technical requirements of the upper casting of the medium-pressure outer cylinder were introduced. The production process of the casting was described in detail:(1)The whole product was placed in the upper box in the lower part,casting system and the core head were mainly placed,instead of the product structure.(2)Using an open casting system to feed molten iron from the bottom surface of the flange.(3)Placing a rwaser at the final solidified portion to solidify the casting.(4)Using Si-Mg alloy and heavy RE spheroidizing agent. The spheroidizing agent was coated with the Si-Ba inoculant,and the Si-Ba inoculant was added with the flow of the iron at the 3/4 tap. The Si-Ba inoculant was added with the iron solution for the post incubation.(5)The superheat temperature of the molten iron was 1 500~1 510 ℃,the tapping temperature was controlled at 1 440~1 450 ℃,the pouring temperature was 1 320~1 330 ℃,and the pouring time was 120 s. The production results showed that the casting size,NDT and mechanical properties test results were all qualified.