Machinability improvement of Inconel 718 during heat treatment - A review

Abstract

The requirement for high strength and heat resistant materials is growing especially in aerospace applications. However, due to mechanical properties such as high wear resistance, resistance to abrasion, and low thermal conductivity, these materials are often difficult to machine, which makes cutting forces and cutting temperatures too high and leads to short tool life. Differences in material microstructures due to differences in chemical composition, casting, and foraging techniques and heat treatment may lead to variations in machinability. Different types of heat treatment are performed on the alloy Inconel 718. The alloy is characterized by the austenite matrix with a unique microstructure, which includes the matrix γ, sediment, y', γ", 5 and carbide. The use of annealing process at different heating temperatures and rates of cooling enhances easy turning and longer tool life. In annealing, metal is heated above the critical temperature and cooled slowly in a medium over some time. Adhesion and hardness properties of the alloy cause short tool life. Elemental distribution, grain morphology, and texture of the built material are carefully evaluated using various material properties methods including TEM, SEM, EDS, and OM. Reviewed.