EFFECT OF WIRE-EDM CUTTING ON FATIGUE STRENGTH OF AZ61 MAGNESIUM ALLOY
Effect of wire electrical discharge machining (wire-EDM) cutting on fatigue strength of an extruded AZ61 magnesium alloy at room temperature was investigated. The surface condition of the samples after the wire-EDM cutting process is compared to the samples which have undergone careful polishing on their surfaces. A series of high cycle fatigue tests are performed on both the wireEDM as-cut and polished samples with constant amplitude stress at the frequency of 10 Hz. Fractographic analyses were conducted on the tested samples to identify the mechanism of fatigue fracture. The finding show that the fatigue limit of wireEDM as-cut specimen is 20 MPa lower as compared to smoothly polished specimens. Fatigue cracks are found to initiate and propagate to final failure from a cutting pit on the wire-EDM as-cut specimens.
UNCERTAINTY ANALYSIS OF MECHANICAL PROPERTIES FROM MINIATURE TENSILE TESTING OF HIGH STRENGTH STEELS
Uncertainty Analysis of Mechanical Properties from Miniature Tensile Testing of High Strength Steels
Deformation parameters in single steel wire-copper matrix composites
By using the single carbon-steel fibre-copper matrix composites, the important parameters controlling dislocation motions in the fibre, matrix and composite, namely flow stress, internal stress, effective stress, change in flow stress due to change in strain-rate or temperature, stress exponent of strain-rate, effective stress exponent of dislocation velocity, activation volume and activation enthalpy were measured at the stage in which the mechanical interaction between the components was negligible. It was found that all the composite parameters were determined only by the properties of the components and for each parameter, a modified rule of mixtures was derived.