The Relationship between Tensile Strain and Residual Stress of High Strength Dual Phase Steel Sheet

Abstract

Abstract. The relation between residual stress and tensile strain is an important factor for evaluating plastic formation grade of steel sheet. The degree of plastic deformation (Δl) and elastic recovery (δ) were obtained by measuring the length of DP600 steel sheet sample under different tensile test conditions, i.e. five tensile strains (ε). Furthermore, the average residual stress value in the surface middle (the diameter of 10 mm) region of above tensile samples was analyzed by x-ray diffraction (XRD) in the crystal plane of (211). By processing the diffraction peak angle (2θ) with half width high method (FWHM), the relationship between sin 2 (ψ) and diffraction angle is attained by least squares method. On this basis, a mathematical model was established to correlate the tensile strain with the residual stress in the present study. The results show that the residual stress decreases and the elastic recovery increases with the increase of tensile strain (ε≤0.205). The relation between residual stress and tensile strain can be described with an exponential function . Finally, a function of tensile strain, elastic recovery and surface residual stress is established, by which a reasonable forming condition, viz. ε=0.205, δ=2.65 mm is determined for achieving the smallest σψ.

Response of Various Extrusion Parameters to Different Outputs: Review

“…According to the improved Tabor model and as indicated in Equation 1, the coefficient of friction (μ) during extrusion is a function of the friction factor (f), strain hardening constant (n), and contact area ratio (𝛼) [36]. This formulation is necessary to forecast μ for various grain sizes during the miniaturization process.…”

“…The micro-extrusion heat generation is less than the conventional extrusion heat generation [36]. Saotome and Inoue (1994), discovered that the dissipation of heat in UFGs rose with an increment in speed of extrusion relative to CGs.…”