机械部件在制造或运转过程中,工件表面往往会出现一些裂纹或类似裂纹状的缺陷,若不加鉴别予以报废处理或者继续使用都是不恰当的,应当进行试验,测量它的长度及深度,然后确定处理方案才是一种比较科学的态度。对于工件表面的裂纹,前几年曾采用四探针测量电阻变化的方法确定其深度,由于裂纹不是完全理想化的断开,裂纹两侧的金属仍有一些耦断丝连的现象,或者完全断开而中间仍 Mechanical parts in the manufacturing or operation process, the workpiece surface often appear some cracks or similar crack-like defects, if not identified to be scrapped or continue to use are not appropriate, it should be tested to measure its length and depth, Then determine the treatment program is a more scientific attitude. For the surface of the workpiece crack, a few years ago, the use of four probe resistance measurement method to determine the depth of change, because the crack is not completely idealized, the cracks on both sides of the metal is still some coupled wire phenomenon, or completely Disconnected and still in the middle