Quality Inspection Of Plasma Sprayed Cladding Layer On The Metal Magnetic Memory Testing Technology

Plasma spray is a typical technique for surface repair, which is used widely for its some advantages such as energy concentration, high efficiency, process stability and easy automation. The center temperature of the plasma arc can be above 15000 K during the spraying, leading to large thermal stress in the substrate; and the sprayed cladding layer is usually borne tensile fatigue loads, stress concentration and fatigue are one of its major damage types, so non-destructive testing for the damage is key to the surface repair of remanufacturing member. The metal magnetic memory is a new nondestructive testing technology, thus the investigation of the detection on thermal stress in the substrate, stress and fatigue damage of sprayed cladding layer on metal magnetic memory technology can be of significant value for research and application of the plasma spray.This paper investigates the effect of thermal stress to the surface magnetic signals firstly. The plasma sprayed cladding layer was made and then detecting the magnetic signals of different testing lines before and after spraying. The variation of peaks-troughs difference ΔHp(y) with the thermal stress was extracted and analyzed combining the variation of microstructure and X-ray diffraction peak FWHM in heat affected zone, to investigate the magnetic memory testing for the thermal stress of plasma sprayed cladding layer.Then the standard static tensile specimens were manufactured from cladding layer. The magnetic signals of different lines at different tensile stress were tested by TSC-2M-4 magnetic memory detector. The variation of normal component gradient, K, and tangential component average value, Hp(x)avg, with the tensile stress was investigated, and then the magnetic domain changes and the magneto-mechanical effect was discussed. The quantitative evaluation for the tensile stress of plasma sprayed cladding layer on the metal magnetic memory testing technique was also investigated.At last, for the standard fatigue specimens of plasma sprayed cladding layer, the surface magnetic signals, plastic deformation and microstructure at different fatigue cycles was observed. The variation of Hp(y) maximum gradient, Kmax, and Hp(x) peaks values, Hp(x)max, with the increase of fatigue cycles was analysed. Then the damage parameter D on the magnetic signals parameter Kmax is proposed to investigate the fatigue damage detection of plasma sprayed cladding layer on the magnetic memory testing technique.