A new approach to the problem of the influence of surface roughness in sheet steel on its formability and on aesthetic aspects of the painted product
Project ID: 7210-KC/404Funded under: ECSC-STEELRES 7C
The so-called "orange peel" irregularity can be defined by analysing the Fourier spectrum patterns of the surface profiles of painted samples. A parameter, LAMM, has consequently been established which represents the power of the components with wavelength between 0.25 and 1 mm, corresponding to the variance profile and measuring the irregularity features against the aesthetics criteria of the Ford method. The classification of surfaces that are freely subjected to stretching, plane strain and drawing show, in terms of traditional roughness parameters, an increase in R(a) which depends only on the equivalent applied distortion (e). These increases are independent of the initial roughness and of the type of deformation. The roughness increment is the same when measured either in the rolling or transverse direction (the major strain e1 is in the rolling direction). The analysis of these surfaces by the spectrum method shows an amplification of the surface unevenness, which depends both on e and on the initial surface morphology. Friction tests by means of the "strip-draw test" technique, and under pressures ranging from 1 to 10 MPa, show that the friction ratio is not affected by the pressure and the nature of the materials used (R(a) = 0.5 - 2.8 micron).
Bibliographic Reference: EUR 13625 IT (1991) 83 pp., FS, ECU 7.50
ISBN: ISBN 92-826-2820-5
Record Number: 199111155 / Last updated on: 1994-12-02
Original language: it
Available languages: it