| In recent years, the progress direction of welded structure is high parameter and good-sized, the working condition becomes more and more rigor and complexity. It is an important issue that the welded structure runs in normal and credibility, which is related to the security of the state's property and human's life. It has a very influential social and economic benefit to identify the quality of welded structure, evaluate the security of service condition and life and prevent the accident occurs.Metal magnetic memory is a new branch of nondestructive testing, which is evaluated ferromagnet item with the information from itself in the condition of geomagnetism field. The base principle of this method is recorded the magnetic flux leakage which is produced in the area of stress concentration.In this paper, the author studied the rules of the signal of metal magnetic memory with the testing time and the testing space. The conclusion is the tested curve has no distinctness with the time elapse, the reason is "magnetic memory" has been come into being when the sample cooled into room temperature. The testing signal was influential by the factor of space, with the instrument away from the crack,no means can test the crack. Study on the signal characteristic of the magnetic memory of crack is the key problem in the quantitative analysis of metal magnetic memory test, after removed the noise from the curve, the author point out the criterion by the mothed of Fourier.Stress and the signal of magnetic memory are very important factor in this new method, this paper researched the law between the main stress and the length of crack, the angle of the crack and the depth of crack. The more depth of the crack, the more great of the main stress; the relation between the main stress and the length of crack is cube; the main stress influenced by the angle is complexity. Based on this research, we set up the model of X65, and the theory value is very answer for the value of test by man. |
PDF Full Text Request