Search

Abstract The paper deals with microhardness measurement up to a depth of 3 μm on hybrid metal matrix composite A359/Al 2 O 3 /B 4 C from the surface created by wire electric discharge turning and abrasive waterjet turning at the same of a range of rotational speed. The study also includes the topographical and morphological aspects of measurements to compare the surface quality. The microhardness was measured by Vickers indentation test at a load of 100 g for 10 s. Surface roughness profile parameters (Ra, Rq and Rz), and 3D surface visualisation were measured by an optical profilometry. Laser confocal microscope was used to characterize the topographical details. FE-SEM analysis was used to discuss the morphological observations and to explore the quality and defects of the machined surfaces. The sub-surface element like residual stresses is also investigated through the depth profile for both types of turning process by means of XRD machine. The results showed that a lower value of microhardness (165 HV) as compared to cast sample (200 HV) has been observed in the recast layer of wire electrical discharge turning along with induction of tensile residual stress (340 MPa). During abrasive water jet turning a nominal change in microhardness (204 HV) along with compressive residual stress (−285 MPa) was observed. [ABSTRACT FROM AUTHOR]

The residual stress and subsurface hardness of welded joints treated by peening using an ultrasonic pulsed water jet at pressures of 20–60 MPa with various traverse speeds and standoff distances were measured. The effect of the treatment was quantified by measuring the residual stress using X-ray diffraction in three regions (the welded zone, heat-affected zone, and base metal). To analyse the depth of the plastic deformation induced by the pulsating water jet, microstructural analyses and micro-hardness measurements were conducted. The surface topography of the treated samples was examined by measuring the surface roughness using a contact surface roughness profilometer. After pulsating water jet treatment, the samples showed both increased residual stress and surface roughness at pressures of 20–60 MPa. Increased subsurface hardness of the treated region was observed up to a depth of 200–250 µm at pressures of 40 and 60 MPa, deeper than that of the sample prepared at 20 MPa. The microstructural analysis identified the involved plastic deformation phenomenon occurred during the treatment process. This method of surface treatment, where the efficiency of the jet is enhanced by the generation of pulses using an acoustic generator, showed promising results for its practical application as a post-weld treatment method. [ABSTRACT FROM AUTHOR]