A novel method for predicting the grain size of superalloy forgings based on the fuzzy method and the FEM

摘要

Grain size is one of the importantindexes for characterizing the macrostructures andproperties of superalloy forgings. Under the conditionthat the quality of the raw material is specified, thegrain size of superalloy forgings is the result ofsynthetic inter action of thermomechanical parameters.Thus, the relationship between grain size andthermomechanical parameters belongs to the fuzzyconcept for which the extension is uncertain. Based onthe results of isothermal constant-strain-ratecompression tests, the membership function forcharacterizing the grain size of superalloy forgings wasfirst established in terms of the thermomechanicalforging parameters. Combining the proposedmembership function with thermoviscoplastic couplednumerical simulation software based on the finiteelement method, a new method was formulated for theprediction of the grain size of superalloy forgings. Theresults predicted by using the method presented in thepaper are in close agreement with the experimental dataand measured grain size of an IN718 alloy disk forging.The proposed method can serve as the guide foroptimizing the forging process and controlling theforging quality of difficult-to-deformation materials.