Research on Depth Evaluation of Surface Crack in Laser Cladding Coating with Metal Magnetic Memory Technology

Abstract

Depth of evaluation method of surface crack in laser cladding coating with metal magnetic memory was introduced in this paper. Laser cladding coating specimen were degaussed, placement direction of specimen and detection direction unchanged, detection speed and lift off value of probe were the constant. Results show that gradient value ofHp(y) signal corresponding to surface crack increases as tensile load increases under the same depth of surface crack, gradient value ofHp(y) signal corresponding to surface crack increases as depth of surface crack increases under the same tensile load. Orientation of internal magnetic domain changes as tensile load changes and magnetic leakage field caused by surface crack are seen as two main reasons for above results. Using fitting method with quadratic polynomial, depth of surface crack in laser cladding coating can be evaluated nondestructively in this paper.