Effect of residual stresses on fatigue strength of high strength steel sheets with punched holes

Effects of cold rolling and annealing time on fatigue resistance of AA5052 aluminum alloy

“…This may be due to the more ductile nature of the annealed alloy compared to the rolled sample allowing a greater number of crack extensions before failure [24]. In addition, these are also attributed to both the reduced dislocation density and tensile residual stress because of recrystallization during annealing [25]. Figure 10 demonstrates the fatigue crack growth rate as a function of stress intensity factor range (ΔK) of asreceived and 45% as-rolled alloy for different annealing times.…”

Modeling of Surface Crack Defects Developed on Shear Edge in High-strength Automotive Steel Sheets

“…Sota GOTO, 1) * Kazuhiko YAMAZAKI, 2) Thi-Huyen DOAN, 1) Yoshimasa FUNAKAWA 3) and Osamu UMEZAWA 4) 1) Steel Research Laboratory, JFE Steel Corporation, 1-1 Minamiwatarida-cho, Kawasaki-ku, Kawasaki, 210-0855 Japan.…”

“…Regarding the fatigue property of punched holes of high-strength steels, the roughness of the shear edge, including surface cracks, is a negative influencing factor on fatigue strength in addition to the residual stress of the punched edge. 3,4) The surface cracks are often rejected as appearance defects. This is because the surface cracks vary in size and it is difficult to predict the influence of the surface cracks on the shear edge properties.…”

Prevention of delayed cracking of punched 1.5 GPa ultra-high strength steel sheets by ironing with punched slug

“…Mori et al [24] examined the occurrence of delayed cracking for blanked 1.5 GPa steel sheets and showed that delayed cracking is prevented by reducing the tensile residual stress around the sheared edge. Shiozaki et al [25] investigated the effect of the residual stress on the fatigue strength for punched high strength steel sheets. Yasutomi et al [26] improved the fatigue strength of punched 1 GPa sheet by reducing the residual stress by means of scrap coining.…”