During heat treatment process, the distortion behavior inevitably appears in hydraulic turbine blade castings. In this research, a technology was developed for real-time measurement of the distortion in hydraulic turb...During heat treatment process, the distortion behavior inevitably appears in hydraulic turbine blade castings. In this research, a technology was developed for real-time measurement of the distortion in hydraulic turbine blade castings at the still air cooling and forced air cooling stages during heat treatment process. The method was used to measure the distortion behavior at the cooling stages in both normalizing and tempering processes. At the normalization, the distortion at the blade comer near outlet side undergoes four stages with alternating bending along positive and negative directions. At the tempering stage, the distortion could be divided into two steps. The temperature difference between the two surfaces of blade casting was employed to analyze the distortion mechanism. The measured results could be applied to guide the production, and the machining allowance could be reduced by controlling the distortion behavior.展开更多
Distortion often appears at the corners of heavy turbine blade castings during heat treatment processes, so a great machining allowance is generally set in production which directly results in cost increase. In this p...Distortion often appears at the corners of heavy turbine blade castings during heat treatment processes, so a great machining allowance is generally set in production which directly results in cost increase. In this paper, a novel real-time measuring technology is developed for non-contact measuring the deformation behavior of heavy steel castings in heat treatment process. It was employed to measure the distortion and the temperature field of a batch of heavy turbine blade castings at cooling stage in normalizing process. Three inflection points appear in the distortion-time curves, and the residual distortion is affected by the regional area of not finished martensite transformation when the second inflection point appears. When the mean air temperature falls into the range of 10℃-20℃, the residual distortion is small; when it is lower than 10℃, positive distortion appears; when it is higher than 20℃, negative distortion appears. The distortion varies with seasonal temperature, which is directly responsible for the great machining allowance given in production.展开更多
Alloy DZ22 possesses rather high intermediate and elevated temperature mechanical properties comparable with the advanced commercial DS al- loy PWA1422.The alloy composition is based on PWA1422 alloy,only the content ...Alloy DZ22 possesses rather high intermediate and elevated temperature mechanical properties comparable with the advanced commercial DS al- loy PWA1422.The alloy composition is based on PWA1422 alloy,only the content ranges of Hf,C and Zr are changed for systematic study.The pres- ent melting technology for master alloy ingot and DS process parameters for components are suitable for this alloy.The alloy revert which has been specially processed can be reused.The mould with- drawal rate during directional solidification affects the crystal orientation,alloy structure and the me- chanical properties of DS castings.The increment of solution-treatment temperature increases obvi- ously the longitudinal stress-rupture life at high temperature but decreases transversal one at inter- mediate temperature.The production practice in batches has demonstrated that alloy DZ22 has not only high mechanical properties but also excellent processing performance,including castability, weldability and machinability.It is indeed a favorable material for advanced aero and land gas turbine engine blades with complex inner cooling passage.展开更多
基金supported financially by the National Eleventh Five-Year Science and Technology Support Program of China through Grant No.2007BAF02B02Major National Sci-Tech Project of China No 2011ZX04014-052
文摘During heat treatment process, the distortion behavior inevitably appears in hydraulic turbine blade castings. In this research, a technology was developed for real-time measurement of the distortion in hydraulic turbine blade castings at the still air cooling and forced air cooling stages during heat treatment process. The method was used to measure the distortion behavior at the cooling stages in both normalizing and tempering processes. At the normalization, the distortion at the blade comer near outlet side undergoes four stages with alternating bending along positive and negative directions. At the tempering stage, the distortion could be divided into two steps. The temperature difference between the two surfaces of blade casting was employed to analyze the distortion mechanism. The measured results could be applied to guide the production, and the machining allowance could be reduced by controlling the distortion behavior.
基金supported by the National Eleventh Five-Year Science and Technology Support Program of China (Grant No.2007BAF02B02)the Major Projects of Ministry of Science of China (Grant No.2009ZX04014-082)
文摘Distortion often appears at the corners of heavy turbine blade castings during heat treatment processes, so a great machining allowance is generally set in production which directly results in cost increase. In this paper, a novel real-time measuring technology is developed for non-contact measuring the deformation behavior of heavy steel castings in heat treatment process. It was employed to measure the distortion and the temperature field of a batch of heavy turbine blade castings at cooling stage in normalizing process. Three inflection points appear in the distortion-time curves, and the residual distortion is affected by the regional area of not finished martensite transformation when the second inflection point appears. When the mean air temperature falls into the range of 10℃-20℃, the residual distortion is small; when it is lower than 10℃, positive distortion appears; when it is higher than 20℃, negative distortion appears. The distortion varies with seasonal temperature, which is directly responsible for the great machining allowance given in production.
文摘Alloy DZ22 possesses rather high intermediate and elevated temperature mechanical properties comparable with the advanced commercial DS al- loy PWA1422.The alloy composition is based on PWA1422 alloy,only the content ranges of Hf,C and Zr are changed for systematic study.The pres- ent melting technology for master alloy ingot and DS process parameters for components are suitable for this alloy.The alloy revert which has been specially processed can be reused.The mould with- drawal rate during directional solidification affects the crystal orientation,alloy structure and the me- chanical properties of DS castings.The increment of solution-treatment temperature increases obvi- ously the longitudinal stress-rupture life at high temperature but decreases transversal one at inter- mediate temperature.The production practice in batches has demonstrated that alloy DZ22 has not only high mechanical properties but also excellent processing performance,including castability, weldability and machinability.It is indeed a favorable material for advanced aero and land gas turbine engine blades with complex inner cooling passage.
