Evolution of Roughness on Straining of Interstitial Free – IF Steel Sheet

Abstract:

This study aims to assess the evolution of surface roughness and waviness parameters with plastic strain in Interstitial Free – IF steel sheet. For the achievement of this study, it was considered various roughness and waviness profile parameters such as: arithmetic average roughness (Ra), maximum distance peak-valley (Rt), average waviness (Wa) and waviness of the total height peak-valley (Wt). Tensile test specimens of IF steel at 0º, 45º and 90º to the direction of rolling were fabricated. After preparing the sheet proof specimens, it was performed simple tensile tests and measurements of roughness and waviness of the specimen surface at various strain stages resulting in a large quantity of data. During the tensile test, it has been measured the following plastic strain to indicate the incremental step: (e1) longitudinal strain and (e2) transverse strain. From these data, it was possible to obtain points needed to plot the curves of roughness and waviness parameters versus strain and to determine the material behavior using equations of the equivalent strain. From the curves drawn it was possible to see how the material roughness and waviness behaves during the straining in the uniaxial tensile state, with the possibility to predict the influence of plastic strain on roughness and waviness parameters and the onset of local necking of IF steel sheet. The waviness parameters Wt is the best for characterizing the onset of local necking.

• Periodical: Key Engineering Materials (Volumes 504-506)
• Pages: 83-88
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.504-506.83
• Online since: February 2012
• Authors: Ricardo Kirchhof Unfer, José Divo Bressan
• Keywords: Roughness Parameters, Sheet Forming, Tensile Test, Waviness

References

[1] S. P. Keeler and W.A. Backofen, Plastic Instability and Fracture in Sheets Stretched Over Rigid Punches: ASM, vol. 56, pp.25-48, 1963.

[2] S. P. Keeler, Understanding Sheet Metal Formability: Part 5 – Die Design and Lubrication, New York, 1968.

[3] Z. Marciniak and K. Kuczynski, Limits Strains in the Processes of Stretch-Forming Sheet Metal. Int. J. Mech. Sci., vol. 9, pp.609-620, 1967.

[4] A.P. Sampaio, C. A. Martins, P. C. Souza, Characterization of Formability of Interstitial-Free Steel. In: Third National Conference of Sheet Metal Forming, Brazil, Porto Alegre, 2003.

[5] J.D. Bressan and F. Barlat, A Shear Fracture Criterion to Predict Limit Strains in Sheet Metal Forming. Int. J. Mater. Form., vol. 3 Suppl 1: p.235 – 238, 2010.

DOI: 10.1007/s12289-010-0750-z

[6] H.W. Swift, Plastic instability under plane stress, J. Mech. Phys. Solid, 1, 1952.

[7] K. Yamagushi and P.B. Mellor, Thickness and grain size dependence of limit strains in sheet metal stretching, Int. J. Mech. Sci., vol. 18, pp.85-90, 1976.

DOI: 10.1016/0020-7403(76)90055-2

[8] A. Parmar, P.B. Mellor and J. Chakrabarty, Int. J. Mech. Sci., vol. 19, p.389, 1977.

[9] M. Fukuda, K. Yamaguchi, N. Takakwa and Y. Sakano, J. Japan Soc. Technol. Plasticity, vol. 15, p.994, 1974.