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BS 6072《磁粉探伤》推荐在磁粉探伤时需要大约30Oe的磁场强度。这通常意味着要求设备输出大电流,以产生所需要的磁场强度,因而这些设备一般都是笨重的。在角焊缝和管焊缝上进行了试验,测量了足以显示被探缺陷所需要的磁场强度,并与推荐值比较。结果表明,足以显示缺陷所需要的磁场强度低于BS 6072的推荐值。本文认为,BS.6072所规定的磁导率值(240)不适用于管道和结构钢。根据所获得的结果,建议以700的值取代。BS.4360 50D型钢的磁导率在Harwell确定的范围内。
BS 6072 “Magnetic Particle Inspection” recommends a magnetic field strength of approximately 30 Oe for magnetic particle inspection. This usually means that the device is required to output a large current to produce the required magnetic field strength, so these devices are generally cumbersome. Experiments were carried out on fillet welds and pipe welds and the magnetic field strength required to reveal the defect being investigated was measured and compared with the recommended values. The results show that the magnetic field strength required to adequately demonstrate the defect is lower than the recommended value of BS 6072. This paper considers that the permeability (240) as specified in BS.6072 does not apply to pipe and structural steels. Based on the results obtained, it is recommended to replace the value of 700. The permeability of BS.4360 Type 50D steel is within the range determined by Harwell.