This paper presents non-perturbing techniques of optical and surface metrology applied to surface studies of daguerreotypes. Daguerreotypes are positive images developed directly on the surface of silvered copper plates. The image is a submicrometre, ultra fine structured surface that exceeds the resolving power of the optical microscope for surface examination. Confocal white light microscopy is shown to be a useful technique for examining the three-dimensional ultra fine structure of the daguerreotype image. This technique provides quantitative information of surface characteristics using established surface roughness parameters to document the daguerreotype surface. Examination at this level can measure changes due to environmentally induced deterioration and provide comparative data of before and after chemical and physical treatment. Confocal microscopy shows considerable potential in the evaluation and documentation of both daguerreotype condition and treatments performed on the image structure. Confocal microscopy was used in the close examination of the Southworth and Hawes portrait of an unidentified man and it demonstrated the ability to unambiguously identify and quantify surface damage. The daguerreotype of an unidentified woman wearing a bonnet was treated with ammonium hydroxide solution to remove tarnish and surface changes were followed with confocal microscopy.

A hot-dipped galvanized zinc-coated sheet steel was deformed with three different laboratory test systems: a Marciniak punch system, a flat-die friction test system, and a cupping system. These systems were able to impose various combinations of deformation modes to the sheet. The deformation modes include: (1) strain without die contact, (2) sliding, (3) pressing, and (4) bending. Strain measurements from the electrolitically gridded specimens were made at the same locations as surface profilometry measurements, allowing a direct correspondence of surface roughness with strain. Quantification of the roughening as a function of strain, sliding and bending was determined. The roughening rate depends upon the strain level as well as the strain path. Increased strain without die contact causes an increase in the surface roughness with strain paths close to plane strain exhibiting the highest roughening rate. The deformation modes of sliding, pressing, and bending cause a decrease in the surface roughness (i.e. smoothing) to occur. A first-order model is proposed to account for the surface roughness as a function of these deformation modes.

‘Three-dimensional surface profilometry’ when used for analysis and product specification reports roughness parameters that provide an average surface description over a relatively large area. Many commercial sheet steels are produced with special textured surfaces for tribological benefits or appearance benefits. These surfaces, as well as others, may demonstrate high levels of roughness anisotropy that is not quantifiable by simple three dimensional surface parameters. This anisotropy can play an important role in the surface appearance of the finished product and in the tribological behaviour during forming. The current work presents a method for quantifying surface-roughness features as a function of angular orientation with respect to rolling direction. The measurement methodology was applied to several model surfaces and one industrially produced electron-beam textured-surface (EBT). This methodology extracts multiple surface-height profiles of the same angular orientation from a single surface and calculates an average roughness parameter for the orientation angle based on the multiple profiles. Particularly interesting results were the large number of profiles necessary to obtain repeatable values for the roughness variation with respect to direction and the strong influence of surface feature size on the repeatability of said results. These results indicate that care must be taken when using a single extracted profile to represent a ‘three-dimensional’ surface.

The morphology of the workpiece surface during and after metal forming operations is dependent on the type and magnitude of the forming operation, the lubrication and the initial surface condition. The current work is a survey of the surfaces that result from mechanical forming of workpieces with different initial surface conditions. The mechanical forming, the bulk material properties and the lubrication condition were maintained as constant as possible. Polished, as rolled, etched, coarsely ground and model surfaces were deformed under plane strain and the surface changes were digitally recorded and examined.

During a study on surface roughening as a function of deformation, an anomalous behavior of the surface roughening for hot-dipped galvanized sheet steel was observed during low levels of imposed strain. A mechanistic model, which explains this surface roughening behavior, is presented. Surface topography parameters, including surface roughness, and relative zinc crystal orientation data, were measured after different amounts of deformation were imposed on the sheet. The proposed model is consistent with both sets of data. The model indicates that the zinc crystals on the surface of the coated sheet steel will initially deform by twinning, which causes a slight increase in surface roughness. The twin regions of the zinc crystals are then favorably oriented for dislocation glide, and the roughness during further deformation will slightly decrease. Once the zinc crystal orientations have homogenized, standard surface roughening due to adjacent grain constraint occurs. Further evidence to support the model include: (1) Twinning in a single crystal of zinc causes a roughness increase of the same magnitude as that found in the zinc coated steel after low strain deformation, (2) twinning of zinc has been observed in other studies of zinc-coated sheet steels, and (3) discontinuous yielding of the steel and recrystallization of the zinc during the sheet deformation did not occur and are not the cause for both the surface roughness and crystal orientation results.

Surface-topography, friction and plasticity form a complex system at the interface of a plastic deformation operation. Surface-topography before deformation affects the frictional behaviour at the interface, which in turn affects the level and distribution of plastic deformation. The surface-topography after deformation operations is determined by a combination of the initial surface-topography, the frictional behaviour at the interface and the level and distribution of the plastic deformation. Friction testing with the asymmetric friction upsetting (AFU) test machine and subsequent surface-topography analysis help to further clarify the relationship between surface-topography, interface friction and plasticity.The frictional conditions during testing are controlled via lubricant viscosity, film thickness, surface roughness, and deformation velocity. High and low viscosity lubricants are used in conjunction with a range of test speeds to produce frictional conditions in the boundary, mixed and hydrodynamic lubrication regimes.The effect of initial surface-topography was examined by preparing five different initial specimen surfaces and recording the surface-topographies before testing. Five surface conditions were used: as received, etched, coarse ground perpendicular to test direction, coarse ground parallel to test direction and polished.A correlation between surface-topography directionality and frictional resistance has previously been observed by testing specimens with grooves machined into the surface at a range of angles [A newly developed test method for characterization of frictional conditions in metal forming, in: Proceedings of the Eighth International Conference on Metal Forming, Krakow, 2000, pp. 91-97; Steel Res. 69 (1998) (4-5) 154160; Beurteilung des Schmierungsverhaltens unterschiedlich texturierter Oberflachen mit Hilfe des Streifenziehversuches, Diplomarbeit Universitat, Gesamthochschule Duisburg, 1996]. In the current work coarse grinding is used in place of machined grooves. The scale of the effect from the surface-topography directionality is compared to the scale of the effect of lubricants, arithmetic roughness value and friction regime.Results indicate that arithmetic roughness value and lubrication regime have greater influence than directionality. These results can be explained via the application of lubrication regime theory and the importance of each component in determining the lubrication condition. (C) 2002 Elsevier Science B.V. All rights reserved.

The present contribution reviews results of research on the effect of the texture on the formation of cracks in electro-galvanised Zn coatings on sheet steel. The Zn coating behaviour was studied during deformation in the absence of die contact in order to avoid frictional effects. In addition, the complex micro-mechanical phenomena that occur during the deformation of zinc coated sheet steel in actual real life manufacturing operations were simplified by subjecting the coatings to well-defined deformation modes only. The crystallographic texture of the Zn coating and the deformation mode were found to have a clear influence on the formation of cracks. The resistance to cracking in all deformation modes was most pronounced in Zn coatings with a majority of the Zn micro-crystals oriented in the high index pyramidal orientation, i.e. with (10.3) parallel to the sheet surface. The presence of some Zn micro-crystals in the basal orientation, i.e. with (00.1) parallel to the sheet surface, is beneficial to avoid the cracking of the coating. The presence of prismatic oriented Zn crystals, with (10.0) parallel to the sheet surface, leads to the formation of cracks in all deformation modes. The high resistance to cracking of the in-sheet (10.3) coating texture is due to the ease of the rotation of the basal planes into an in-sheet orientation during the deformation.

The forming of coated sheet steel products is performed for a wide range of processing conditions. This article examines the effects of die history on the frictional nature of the sheet-die interface. It has been found that as successive tests are performed on a die from the as-lapped condition to the “run-in” condition, the die surface morphology changes significantly and the coefficient of friction, μ, decreases. Changes in surface roughness as well as scratch formation on the die are believed to affect the nature of the die-workpiece, lubricant interaction. The findings in this study suggest that the extensive polishing procedures used in the manufacture of new stamping dies should be carefully reevaluated.