Volume 50, Issue 3

Image analysis investigations into the quantitative characterisation of hot formed duplex steel microstructures are presented. The shape parameters Feret diameter, Feret angle and roundness are used to describe the morphology of the microstructures. High temperature compression tests were carried out at 1 150 °C, 1 200 °C and 1 250 °C and the microstructures produced compared with that of the initial un-deformed material. The technical yield strength were also correlated with the temperatures and strain rate used. This revealed that the technical yield strength doubled by reducing the temperature of deformation from 1 250 °C to 1 150 °C and by increasing the strain rate by an order of magnitude. It is also shown that the pronounced preferential direction of the phases present in the initial un-deformed material is no longer quantitatively discernable above a temperature of deformation of 1 200 °C.

The results of some lead-free bronzes characterization are presented in this paper. Investigated samples, produced in the Company for production, processing and trade of non-ferrous, rare and noble metals “11. mart” AD Srebrenica (BiH), were examined using optic microscopy, hardness, microhardness and electric conductivity measurements in order to determine their structural, mechanical and electric characteristics.

Besides its original field of application–the characterization of microstructures–the metallography is often referred to when analyzing failures of electronic components and assemblies. In this context, the cause of the failure is analyzed by means of a metallographic section. At this point, the precondition and difficulty is the right choice of the section plane. If it is not optimally selected, there is a risk of overlooking the defect and therefore of not recognizing important correlations. The X-ray computed tomography is an efficient method which helps making the right choice and facilitates a targeted metallographic preparation. Conspicuous features inside the damaged component can be detected in advance by means of a three-dimensional volume model established by computed tomography. Based on this information, an appropriate cutting plane can be chosen in the volume model and a targeted metallographic section can be prepared. In the following, it is possible to view the conspicuous spot with high resolution and to analyze its microstructure in selected areas. In order to demonstrate the use of computed tomography as a supporting technology in the target preparation, the following article establishes a link between both testing technologies and their application to the press-fit technology which serves as joining technology when assembling electronic components.