基于磁记忆技术的等离子喷焊熔覆层疲劳损伤检测

For investigating the variation of magnetic signals on surface of plasma sprayed cladding layer during fatigue damage, tensile fatigue tests of plasma spraying specimen was carried out. Meanwhile, the normal component of magnetic signal, Hp(y), and tangential component, Hp(x), at different loading cycles was measured through the tests. A new damage parameter D was established by the maximum gradient Kmax in order to explore the feasibility of damage evaluation to cladding layer on the Metal Magnetic Memory Testing Technology. The results indicate that the Hp(y) mutated with maximum gradient Kmax, Hp(x) mutated with peak value Hp(x)max, and the Kmax value increased exponentially with the increase of the fatigue cycles. In the initial stage of fatigue, the Hp(x)max increased quickly, and the plastic deformation was rapid ; in the middle stage of fatigue damage, the Hp(x)max and plastic deformation increased gently; in the last stage of fatigue, the Hp(x)max had a rapid growth again, and also the plastic deformation. The damage parameter D increases with the recirculating ratio N/Nf, which is similar to the growth process of fatigue damage, thus the fatigue damage and residual life can be got by calculating the damage parameter D. ?????