Abstract
Machining of nickel super-alloys is difficult since mechanical hardening and, consequently, extreme tool wear occur. In the case of turbine blades, castings can no longer meet stringent requirements for precision; hence, they are being ground or milled in order to comply with the demanded dimensions. In this contribution, castings made of Inconel 738LC were machined by four axis milling. The resulting surface of gas turbine blades are characterized by several surface integrity parameters with respect to the structural inhomogeneities caused by mutual effect of plastic deformations and thermal fields during the cutting process. Moreover, the impact of effective contact area of the cutter was considered as well. It will be shown that ideal machining parameters viewed from the standpoint of surface roughness and economy of the whole machining process can lead to appreciable tensile normal stresses.
Highlights
Turbine blade represents a crucial product of today’s world and its durability, reliability, fatigue life, or quality, have far reaching consequences for areas ranging from power generation to aircraft safety
The resulting surface of gas turbine blades are characterized by several surface integrity parameters with respect to the structural inhomogeneities caused by mutual effect of plastic deformations and thermal fields during the cutting process
The blade milled with parameters evaluated as roughness-cum-economy most convenient showed Ra ≈ 0.5 and Rz ≈ 2.3 and the obtained values of residual stresses (RS) are in Tab. 2
Summary
Turbine blade represents a crucial product of today’s world and its durability, reliability, fatigue life, or quality, have far reaching consequences for areas ranging from power generation to aircraft safety. Nickel super-alloys are an important group of materials used for gas turbine blades because of their heat resistance and favorable mechanical properties such as high strengths at elevated temperatures. These features stem from complicated microstructure with interplay between γ and γ’ nickel phases, various carbides and the real structure of individual crystalline phases that is distinguished by a complex character [1] of grain boundaries, presence of defects such as vacations, dislocations, stacking faults and residual stresses (RS). It would be appropriate to determine the stresses in the blade after the final manufacturing step and upon modelling the dynamic load, when superposition of residual and load stresses takes place, decide how influential or even critical the RS can be and whether it is, desirable to change the production parameters
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
