Roughness and Hardness of 60/40 Cu-Zn Alloy
— The functional performance of machined components, often, depends on surface topography, hardness, nature of stress and strain induced on the surface, etc. Invariably, surfaces of metallic components obtained by turning, milling, etc., consist of irregularities such as machining marks are responsible for the above. Surface finishing/coating processes used to produce improved surface quality/textures are classified as chip-removal and chip-less processes. Burnishing is chip-less cold working process carried out to improve surface finish, hardness and resistance to fatigue and corrosion; not obtainable by other surface coating and surface treatment processes. It is a very simple, but effective method which improves surface characteristics and is reported to introduce compressive stresses. micro-irregularities start moving in the direction of the newly formed surface. The grain structure is condensed, producing a smoother and harder surface with superior load-carrying and wear-resistant capabilities. 2 + 0.0525X 4 + 0.0125X 1 X 4 − 0.02X X 4 − 0.0375X 3 X 4 Hv=160.625 − 2.37 5X 1 + 5.125X 2 + 1.875X 3 + 4.375X 4 − 1.625X 1 X 4 + 4.375X 2 X 4 − 2.375X 3 X 4 High surface microhardness (175H V ) was obtained at 400rpm, 2passes, 0.05mm/rev and 15kgf., and high surface finish (0.20µm) was achieved at 30kgf, 0.1mm/rev, 112rpm and single pass. In other words, surface finish improved by 350% and microhardness improved by 21% compared to as machined conditions.
Influence of burnishing process on surface roughness, hardness, and microstructure of some non-ferrous metals
Burnishing is a cold working process, which easily produces a smooth and work-hardened surface by plastic deformation of surface irregularities. In the present work, the influence of the main burnishing parameters (speed, feed, force, number of tool passes, and ball diameter) on the surface roughness and the hardness of two different non-ferrous metals were studied. Furthermore, subsurface hardness and microstructure under specific conditions were also studied. It was found that the burnishing forces and the number of tool passes are the most pronounced parameters, which have great effects on the workpiece's surface during the burnishing process. A simple, inexpensive and newly designed ball-burnishing tool, with interchangeable adapter for using different ball diameters, was used throughout the experimental work presented in this paper.
Residual stress distribution in burnishing solution treated and aged 7075 aluminium alloy
Abstract The residual stress distribution in the surface region of solution treated and aged 7075 aluminium alloy workpieces that are orthogonally burnished under lubricated condition is determined using a deflection etching technique. The residual stress at the surface is low compressive and increase rapidly with an increase in depth beneath the burnished surface to a maximum compressive then decreases gradually with further increase in depth becoming vanishingly small tensile or compressive. The maximum residual stress and depth of the stressed region increase in burnishing speed, force and an increase, to some extent, in burnishing time. The results are interpreted qualitatively in terms of the variations in the amount of surface region deformation produced by changes in burnishing conditions.