Production and research status of inlet cylinder castings

Before 2013, the company’s production performance of gas turbine castings was dominated by only a few small and medium-sized steel castings such as valves, gas seals and blade rings, and almost all the large cylinder castings and other difficult parts and components required for supporting were purchased from the external market. Theoretical and technical research and production experience of nodular cast iron gas turbine inlet cylinder castings were not accumulated. From 2013 to 2017, the gas turbine market has a good development prospect. Market procurement alone can not meet the company’s needs for supporting the turbine, and the product quality, cost price and delivery nodes of castings are subject to different degrees of control. The company began to set up a project to study and explore the casting technology of large castings such as inlet cylinder, compressor cylinder, combustion chamber and compressor cylinder, turbine cylinder, etc.

On the one hand, it can alleviate the pressure of production capacity being controlled by people, on the other hand, it can also improve the technical level of heavy gas turbine large castings manufacturing, reduce the company’s procurement cost, and provide guarantee for the company’s strategy of independent research and development of gas turbine and vigorously develop casting and forging industry in the future. In the F-type heavy duty gas turbine project currently developed by our company, our department is mainly responsible for the casting technology research and manufacturing of cylinder castings. There are 4 sets of supporting castings for the F-type gas turbine, including inlet cylinder (material: fcd450), compressor (material: scph2), turbine cylinder (material: scph21), combustion chamber and compressor cylinder (material: scph21).

The nodular cast iron gas turbine inlet cylinder castings studied in this paper mainly rely on a single domestic company to meet the company’s matching needs. When the castings are purchased back to the factory, there are some problems such as dimension deviation, shrinkage cavity and porosity, and even two sets of cylinder castings are scrapped due to quality problems. Since 2013, our company has started the research and trial production of the manufacturing technology of the inlet cylinder castings, but there are many problems in the early production of castings, such as shrinkage cavity and porosity defects, excessive slag inclusion and inclusion defects with linear and large-area magnetic marks on the surface of castings during magnetic particle testing, and poor stability of casting production process. Although small batch feeding production has been realized after 2014, the above casting defects still occur frequently due to the change of manufacturing conditions such as casting raw materials and auxiliary materials. In the second half of 2016, five sets of intake cylinder castings produced in different degrees of batch shrinkage and porosity quality problems. Our company’s research on the casting technology of the intake cylinder has been in the stage of continuous research and development and exploration.