Mohamed H. Alaalam - Industrial Research Center, Director of Laboratories and Technical Development Department, Libya

Infrared thermography techniques have been used for some time in a number of engineering applications but only recently has the method been applied for fatigue measurments of materials. This new methodology presents many advantages as apposed to the conventional Wöhler method. Compared to traditional method this technigue enables the determination of fatigue limit in a short period of time, a small number of test specimens are required, NDT techniqe. In Austempered Ductile Iron (ADI) this leads to saving in material, mahcining, heat treating and testing costs. Variation of fatigue properties with austenitising time and tempertaure of a ductile cast iron containing copper and nickel was investigated. In general samples heat treated at 850,900,950, and 1000℃ for 15 to 360 min have fatigue strength values which increases as the soaking period increases and fall with further holding in the bath. This paper shows that infrared termographa can be use to determine the fatigue properties of ADI. The fatigue limit can be determined following accurate temperature masurments of the specimen's surface during cyclic loading and subsequent analysis of the thermal date. The optimum fatigue strength occurs at 900℃ and that the former drops as the solution treatment temperature incease to 1000℃.

NDT, Infrared, Fatigue, Austenitising, Ductile, and Austempering