Material , Structure and Hardness testing of Cast-iron safety parts by using NDT methods

In the past , the producers of safety cast -iron parts were executing only random check to control their production line as relatively high rate of defective parts were acceptable . Nowadays due to the market demand because of producing high speed vehicles , continuos decreasing the weight of parts and consequently using lower safety design factor and finally due to the high competition in the word market , very high quality parts are only demanded and very low rate of defective parts even lower than the range of PPM is acceptable .Therefore , random check is no more sufficient at all , and 100% of products should be tested . In testing safety parts , 2 categories of test must be executed :1-Flaw detection to find defects like : porosity , shrikage . cracks and inclusions .2- Checking material mix , structure , heat treating process , Microscopic texture , graphite type and properties like tensile strengh , hardness and case depth . In this study we concentrate on the second category of tests.All of these tests can be done only by fast , reliable and re - producable NDT methods.Different NDT methods like Eddy Current testing (ET) , Ultrasonic Testing (UT) , Resonance Testing , Vibration analysis (VA) or Thermograhy are used for 100% testing of such parts.In this paper more common methods i . e ET and UT nd their capabilities as well as applications are described The practical test on production line of Pride passenger cars to check the nodularity and hardness of 3 types of cast - iron safety parte by both methods have been reported By comparison of the results of both methods on the same parts , the conclusion and comments to select the proper test method has been presented.