Automatic Counting of Non-Metallic Inclusions in Ferrous Powders for Powder Forging

The non-metallic inclusions in fully dense PM products are supposed to affect the mechanical properties, but it is difficult to know to what extent. General investigations concerning the mechanical properties of inclusion containing materials, especially the dynamic properties, should take account of the influence of non-metallic inclusions; their size and number may also be important. Measuring techniques are relevant in this connection, because the results will vary considerably, depending on the method of defining the extent of inclusions composed of more or less dispersed minute subparticles. Such inclusions will be referred to as ‘spotty’ in this paper. Two measuring techniques are described, as well as the outcome of actual measurements performed on four forged PM materials with varying inclusion contents. The results are correlated with the mechanical properties of these materials. The conclusions drawn from these experiments stress the need to specify the measuring technique when reporting inclusion contents in powder forged materials. PM/0392