Влияние лазерного воздействия на усталостное разрушение сплава 2024-Т351

We study smooth specimens of rectangular cross section made of aluminum alloy 2024-Т351 (analog of D16T) after laser surface hardening. Every pulse was overlapped by two other pulses. After hardening four-point bending tests were performed on the specimens in stress interval 270-300 MPa, with frequency 20 Hz and cycle asymmetry R = 0.1. It is found that at σmaxmax = 270-295 MPa. The left fatigue curve with the parameters σa8.8Nf = 8.82 ⋅ 102 characterizes crack nucleation on the surface, which corresponds to the minimum specimen lifetime. The right branch of the fatigue curve with the parameters σa21.28Nf = 8.18 ⋅ 1058 characterizes crack nucleation beneath the surface, which corresponds to the maximum specimen lifetime. In the kinetic diagrams of fatigue crack growth the laser hardening of specimens is manifested in a delay of their propagation under the action of residual stresses at stresses σmax