Study On Effect Of Solidification Parameters On Dentritic Structure And Mechanical Properties In Ni-Based Superalloys

The effect of solidification parameters on dentritic structure and mechanical property of a Ni-based superalloy turbine blade has been investigated. According to the investigation, the dentritic structure and mechanical property of casting are numerically simulated, using the software of"Anycasting"to optimize technological parameters and get castings with excellent structure and property. The mold filling sequence and solidification sequence of blade are simulated by Anycasting. In addition, shrinkage defects in blade are predicated. The predication result has a better agreement with the experimental observation.Grain size and SDAS at different cross sections were measured. The measurements change with different places. Grain size of the body of blade varies from 0.85 mm to 3.22mm, and SDAS varies from 51μm to 95μm, while grain size and SDAS of rabbet of blade are 5.58mm and 117μm respectively. The grain size and SDAS increase with the decrease of the distance from the cross section to the ingate, reduce with the increasing of section thickness.Relationships between SDAS and solidification parameters have been studied. It is found that SDAS reduce with the increase of cooling rate and decrease of solidification time. Mathematical relationships are derived according to the measurement results.Relationship between SDAS and mechanical property represented by HV has been studied. Results show that HV reduce with the increase of grain size and SDAS. Relationships are derived according to the experiment results. Grain size, SDAS and HV of blade are numerically simulated by Anycasting.Compared with experimental results, the prediction results fit well with experimental results. Then, grain size, SDAS and HV in different processing casting conditions including the effects of felt are simulated. Results show that grain size and SDAS decrease with the decrease of pouring temperature, while HV increases. Grain size and SDAS increase with the increase of mold preheating temperature, while HV decreases. But the grain is much uniform when mold preheating temperature is high. Grain size and SDAS increase while HV decreases with felt.