用金属磁记忆法测评焊接质量

Metal Magnetic Memory Method Used for Evaluation of Quality of Welded Joints

介绍用金属磁记忆(MMM)效应,测定和评析承压设备焊接接头质量的新方法。此法已在我国电力工业上成功应用。MMM法是基于自漏磁场分布进行评析的NDT方法,自漏磁场是在产品焊接和设备运行期间自然形成的,其读数能以快检模式测评实际焊接状态,其图像可显示结构力学不均匀性、残余应力分布和焊接缺陷等信息。检测前,焊缝金属表面一般无需清理。这里给出了对不同类型、尺寸的容器、管道焊接接头用MMM法检测评析示例,并与常规NDT方法(RT、UT)作了比较,效果彰显。本文意在为推广MMM技术在承压设备在制在用检测上的应用,开辟新通道。

A new method of measuring and evaluating the quality of welded joints,by use of metal magnetic memory(MMM)effect,is introduced.The MMM method has been successfully implemented in China’s electric power industry.It is a non-destructive testing method based on distribution analysis of the selfmagnetic leakage field(SMLF)naturally formed during product welding and equipment operation.The SMLF reading provides a unique possibility to integrally assess in a quick testing mode the actual weld state.Its image displays information on structural inhomogeneity,distribution of residual stresses and welding defects.Before testing usually no weld metal surface preparation is required.Here are some examples of inspection and estimation by the MMM method for welded joints of different dimension-type vessels and pipelines,comparing with conventional NDT methods such as UT and RT,and the results obtained are positive.The author’s intention is to pave a new way for promoting the application of the MMM method in the production and service inspection of pressure equipment.