材料的强度特性通常是根据其变形或破坏状态的计测来评判的。现行方法多半采用破坏制件法、截取试件法或标准试样法。目前,世界上较先进的方法是无损检测法NDT(non destructive testing)。实施NDT时,既不需损坏制件,也不必截取试件,便能检测出内部缺陷。它是利用了缺陷使材料本身的各种物理性能如声波、光学、射线、电磁及热等特性发生变 The strength characteristics of a material are usually judged on the basis of the measurement of its deformation or failure state. The current methods are mostly broken parts method, interception specimen method or standard sample method. At present, the most advanced method in the world is NDT (non destructive testing). When NDT is implemented, internal defects can be detected without damaging the parts or intercepting the test pieces. It is the use of defects to make the material itself a variety of physical properties such as sound waves, optics, radiation, electromagnetic and thermal characteristics of change