Study On Stress-magnetic Memory Effect Defective Flat Based On Iron

The magnetic memory testing technology is the emerging development a nondestructive testing technology. The magnetic memory testing plays an important rolein detection of chemical equipment and artifacts. Use metal magnetic test candetermine the material stress concentration and detect location. Plays an importantrole in discover the detect location to avoid some vicious accident. However magneticmemory testing technology introduced to china only a few years, the main use inmechanism of magnetic memory. Magnetic memory testing method to determinedetect size and shape still a blank, there is no function relationship between themagnetic signals and load size. That technology need to do a lot of experiment andresearch.In this study, for plat of Q235carboon steel, by detected magnetic signals understatic tension condition, some regulation between magnetic and diameter of hole, aswell as load and thickness of plate are proved. Test piece total of15, including threeblack test piece, The thickness of the plate was4,6,8mm, the diameter of the holewas3,6,9mm and12mm6measurement route for every plate, the first study forblack test piece.For the same aperture, the same measurement route, the same thickness ofspecimen, different load, found that magnetic memory cure looks irregular anddisorderly, did not find any law. On magnetic field the surface of intensity distributionpatterns, with the increase of the load, the magnetic field strength curve is close tozero, zero accurately indicates the defects position.For the same load, the same measurement route, different thickness of specimen,load for0KN and18KN, found that load for0KN, thickness of specimen for3mmsurface magnetic signal was oblique line, did not find zero-crossing point. Diameterof the hole is6mm began to field strength curve peaks and troughs, when theDiameter of the hole is for12mm, the magnetic field strength curve fluctuation was max, wave crest change were catastrophe. For the aperture3mm, load for18KN,find that surface magnetic signal was oblique line. Aperture of6mm,9mm,12mmmagnetic field strength curve and zero straight line have the focus, the focus generallyindicates the location of the hole.The study for the same load, the same aperture, different measurement route,found that the magnetic field strength curve for lengthways were coincident, themagnetic field strength curve for horizontal were coincident. Found that there is arelationship between the magnetic field strength and test direction.By processing the breaking test for one plate, find that magnetic signals curveinto S type, fluctuation of magnetic signal is very large, magnetic field strength valuesof about±1000A/m, magnetic signals were changed after fracture rapidly.Detection the magnetic field strength for surface of opening test piece, find thatthe magnetic signal curve roughly the same, distribution of magnetic signal areirregular. Unable to confirm among the magnetic field strength and load, aperture sizeand the thickness. But found that the magnetic field intensity distribution of thefracture crack detection very regular. Compared with the magnetic signal for breakinglocate and magnetic signals for pinhole is very different. Study the magnetic fieldstrength for perforate test piece, found that should put the project extends to crackdetection in pipes, in order to realize the experimental and practical combination.