The Effect of Electrochemical Machining on the Fatigue Strength of Heat Resistance Alloys

Electrochemical Machining (ECM) provides an economical and effective method for machining high strength, heat-resistant materials into complex shapes such as compressor and turbine blades, dies, molds and micro cavities. ECM is performed without physical contact between the tool and the workpiece in contrast to the mechanical machining, and without strong heating in the machining zone in distinction to the methods such as EDM. Therefore, no surface metal layer with mechanical distortion, compressive stresses, cracks, and thermal distortion forms in ECM. ECM is often used even for removing a defective layer, which has been formed in EDM, with the aim to improve the surface integrity. However, sometimes the intergranular attack occurs in ECM. This may reduce the performance of machined parts and lead to the decreasing of fatigue strength.

In this paper, the effects of ECM on fatigue strength of heat resistant alloys such as nickel-base alloys and titanium alloys are presented. The problems of the intergranular attack, hydrogen embrittlement and surface roughness as result of ECM parameters are described.