Volume 59, Issue 3

In recent years additive manufacturing techniques for metals became more and more enhanced and a great variety of processable materials are available. Nevertheless, the quality of 3D-printed components is often not obvious, and, depending on the material, it is not known whether they are as resilient as conventionally manufactured parts. In this paper rolled tensile test samples made of 17-4PH are compared with additively manufactured ones. For this purpose, they were printed by Laser Powder Bed Fusion in three different orientations, 0°, 45°, and 90°, and subsequently tensile tested. The presented results contain mesoscopic images of the fracture surfaces, as well as an analysis of the metallographic microstructure. Further details about the measured hardness, the phase diagrams as well as an optimized heat treatment are described in detail. It is shown that specifically the heat treated specimens with a 45° orientation reaches the highest ultimate tensile stress, but possess a low ductility in comparison to the conventional components.

The effects of heat treatment process on the microstructure and mechanical properties of S47450 bolt materials were studied by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), tensile test, impact test and hardness test. The results showed that in the temperature range selected by the test, the quenched martensite of the bolt material after quenching at 1070 °C and tempering at 670 °C was fully refined and evenly distributed, and the precipitation of Cr 23 C 6 played the role of precipitation hardening. It showed the excellent comprehensive mechanical properties, with the Brinell hardness reaching 295 HBW and the tensile strength of 1035 MPa. The elongation was 16 %, and the impact energy at room temperature was 21 J.

One definition of failure is that the subject component lost its function intended by design. The case study presented in this contribution is admittedly borderline in this respect. The parts in question have never seen any engine service and were taken straight out of fabrication, namely the weld shop. Welded components for turbomachinery exhibited excessive areas of lack of fusion in welds. Some of the subject assemblies were put in engine service in non-OEM machinery, without experiencing any failures. This was before weld imperfections were detected in fabrication. However, even though faulty components did not yet fail in service, the presented case is still categorized as a failure case, since the subject weld imperfections were so severe that failure had to be considered imminent. This