A linear friction welding process model for Carpenter Custom 465 precipitation-hardened martensitic stainless steel: A weld microstructure-evolution analysis

Our recently developed fully coupled thermo-mechanical finite element-based process model for linear friction welding has been combined with a newly constructed microstructure-evolution model in order to predict the type, the extent, and the temporal evolution and spatial distribution of microstructural changes within different portions of the weld. The newly constructed microstructure-evolution model is based on the key physical metallurgy concepts and principles of the workpiece material and includes the basic thermodynamics and kinetics of various interacting and competing phase transformations, which may take place within the weld region. The microstructure-evolution model is subsequently applied to Carpenter Custom 465, H1000, a high-strength/high-corrosion resistance, precipitation-hardened martensitic stainless steel. Combined use of the thermo-mechanical process model and the workpiece material microstructure-evolution model enabled establishment of the basic relationships between the linear friction welding process parameters (e.g. friction pressure, reciprocating amplitude, reciprocating frequency, and forging pressure), temporal evolution and the spatial distribution of the as-welded material microstructure. Examination of the results yielded by the model clearly revealed: (a) the presence of three zones within the weld, that is, (1) a contact interface region, (2) a thermo-mechanically affected zone, and (3) a heat-affected zone and (b) the fact that the relative size and the extent of the associated microstructural changes are controlled by the selected linear friction welding process parameters. While there are no publicly available reports related to Carpenter Custom 465 linear friction welding behavior, to allow experimental validation of the attendant microstructure-evolution model, these findings are consistent with the results of our ongoing companion experimental investigation.