Projects & Publications
"Influence of printing parameters on part density in L-BPF of Ti-6Al-4V and correlation with static mechanical properties measured using indentation testing"
#RISO2024 | RISØ 2024 - IOP Conf. Series: Materials Science and Engineering 1310 (2024) 012030 - IOP PublishingJ Schulz(1), E C Santos(1), A Kalliath(2), B Schmaling(2), P Zok(2), S Siegert(2),I S Dandu(2), KH Lindner(2), E Bruder(3) and K Durst(3) | (1) IQS, Carl Zeiss IMT GmbH, Oberkochen, Germany; (2) Imprintec GmbH, Bochum, Germany; (3) Department of Physical Metallurgy, TU Darmstadt, Germany
Abstract. A complete workflow of parameter development and process qualification of a part manufactured using laser powder bed fusion (L-PBF) AM technique requires data of porosity, pore morphology, distortion and static mechanical properties. Using a combination of two non-destructive techniques: Computed tomography and indentation testing, the influence of printing parameters on defect types and part density in L-PBF of Ti-6Al-4V is described. In addition, the results using the combined method are compared to conventional testing methods.
"Effect of Pulse Current GMAW on the Yield Stress of the S460M TMCP Steel Welded Joints"
#MMI | 2022-07 | Metals and Materials International A. Zavdoveev, P. Zok, V. Pozniakov, M. Rogante, T. Baudin, M. Heaton, A. Gaivoronskiy, S. Zhdanov, P. Acquier, T. Solomijchuk, V. Kostin, M. Skoryk, I. Klochkov & S. MotrunichAbstract: "Thermomechanically cold processed (TMCP) steels with a high level of strength are actively used in various constructions. The high strength of the TMCP steels is acquired due to the formation of the fine-grained structure. Such steels have relatively low carbon percentage. These greatly simplify the solution of the problem of improving the quality and reliability of metal structures. At the same time this raises new questions in terms of the technology for welding such steels. In the first instance, it is conditioned by the complex behavior of the TMCP structure under the welding thermal cycle effect. The most important property of the welded joint is yield stress (YS) which characterizes the workability of the whole joint. The estimation of the YS while developing the welding technology is a valuable task for design. This current research has made a complex investigation of the modern welding technique's effect on the behavior of the yield stress formation in TMCP steel welded joints. For progressive technology development, pulse arc welding was used."
"Fine-grained low carbon bainitic steels with improved properties."
H. Roelofs, P. Zok, B. Schmaling#HRPZBS | 2019-07 | Conference Paper on
ResearchGateAbstract: "Reducing the weight of car components has led to more filigree parts over the last decade and the use of stronger materials. Conventional solutions with quenched and tempered steels not always fulfil the demands concerning technical reliability, economics and environmental friendliness. Thermomechanically processed and continuously cooled bainitic steels are clearly better for demanding applications balancing these material's aspects which has led to a successful introduction of new steel grades into car components during the last decade. However, bainitic steels often do not reach the high Charpy impact toughness values of quenched and tempered steels. This is in particular true at sub-zero temperatures and after thermal or thermo-chemical treatments. Applying innovative technologies, the above mentioned handicap of bainitic steels can be reduced or completely eliminated by refinement of the prior austenite grain sizes (not only in flat products but also in long products). In the present work the industrial production technology "XTP" was applied to produce fine-grained low carbon bainitic-martensitic steel bars. In comparison with conventionally hot rolled bars the Charpy transition temperature then was decreased by ~60°C. The influence of a tempering treatment on mechanical characteristics was investigated in detail and will be discussed. Results demonstrate significant improvements in comparison with conventionally produced bars. The unique property combinations found in these new products open new perspectives for them in challenging applications."
"DIN SPEC 4864"
#DS4864 | 2019-11 | Technische Regel im Beuth VerlagA. Braun, T. Chudoba, M. Griepentrog, M. Schäfer, B. Hachmann, B. Schmaling, P. Zok, P. Beisel, P. Reinstädt, F. Menelao
Einführungsbeitrag: "Diese DIN SPEC wurde im Zuge des PAS-Verfahrens durch ein DIN SPEC (PAS)-Konsortium (temporäres Gremium) erarbeitet. Die Erarbeitung und Verabschiedung dieser DIN SPEC (PAS) erfolgte durch die im Vorwort genannten Verfasser. Dieses Dokument legt ein Prüfverfahren zur Bestimmung von Fließkurven von metallischen Werkstoffen mittels zerstörungsarmem Prüfeindruck, 3D-Vermessung und Finite-Elemente-Werkstoffmodell fest. Die Fließkurven dienen zur Ermittlung von Vergleichskennwerten zu Kennwerten aus dem Zugversuch nach DIN EN ISO 6892-1. Dieses Verfahren gilt für Werkstoffe: - die sich plastisch verformen, - die beim Eindringen des Prüfkörpers einen Aufwurf im Randbereich des Prüfeindrucks erzeugen, - dessen Korngröße maximal 1/3 des Eindruckdurchmessers beträgt und - welche kein Lamellengraphit/Kugelgraphit/hohe Porosität oder Gefügebestandteile enthalten, die einen Festigkeitsunterschied in Zug und Druck bewirken. Das Verfahren kann durch eine werkstoff- und probenspezifische Anpassung (Kalibrierung) ergänzt werden. Das Verfahren liefert quantitative richtungsunabhängige Ergebnisse. Bei geringer Eindringtiefe kann das Verfahren qualitativ zur Beurteilung von richtungsabhängigen Fließkurven und Vergleichskennwerten genutzt werden."