Detection of Crack Growth Rate in 45 Steel by Metal Magnetic Memory

It is important that monitoring the fatigue crack propagation in engineering. This paper studied crack growth rate with the metal magnetic memory technique. Three-point bending fatigue tests of center-cracked specimens were carried out and the normal component of magnetic field signals H-p(y) on the surface of specimens were measure by TSC-1M-4. The correlation of crack growth rate da/dN and metal magnetic memory normal signal H-p(y) was studied. The specimens, with different heat treatment, quenching and thermal refining, were tested in fatigue-testing Machine to study the influence of heat treatment on the metal magnetic memory signal H-p(y). The curve of da/dN similar to H-p(y) was built.