Research On The Relationship Of Residual Stress Subjected To300m Steel’s Tensile Load And Magnetic Memory Signals

300M steel in processing and using process would have residual stress whichimpact on the material fatigue strength, plastic, toughness and so on. Whenferromagnetic material is loaded by external stress, the material under geomagneticfield will occur magnetostrictive effect and cause that magnetic domain structure hasdirectional and irreversible change which is magnetic memory effect. Thus, metalmagnetic memory testing can early diagnose residual stress size and distribution for300M steel components.Based on ferromagnetic study, fracture mechanics, the principle of minimumenergy, stress analysis model for300M steel plate with classic defect and nonlinearelastic-plastic stress load is established by using the finite element method which give300M steel stress-strain curves by solving surface stress distribution. Compared withexperimental data for flat with hole and slot obtained by tensile experiments, samplesurface leakage magnetic field measurement in magnetic memory testing, samplesurface residual stress measurement in X-ray stress instrument, the results indicate thatin the stress concentrating place, normal magnetic field Hyon the sample surface willhave change sharply. If the load and form variables are small, normal magnetic fieldHywill change more smoothly, but when the stress goes into plastic areas, Hywillhave drastic change and even appear jumping phenomenon. In addition, the studyshows normal field gradient of300M steel has relationship with load and residualstress which normal field gradient of300M steel have a parabola relation with load;and single value relation with residual stress in the elastic zone and plastic zone wherefrom the elastic zone into the plastic zone, K has increased dramatically and normalfield have jumping, evaluating to determine the stress concentration area.300M steel is a common manufacturing material for domestic air landing gear.Soits fail-safe analysis and especially detecting damage stress concentration for300Msteel components in service is very important for airline security and neednondestructive testing technology to research. Therefore, this research conclusion canprovide theory support for early detecting stress concentration of landing gear and helpinterpret magnetic memory mechanism.