Fracture initiation in FCC and BCC metals during tribology

• Applicant: Privatdozent Dr. Steffen Brinckmann
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2016 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 324591046

According to the current scientific understanding of wear of metals, the crack initiation mechanism is linked to surface fatigue, which occurs as the metal experiences repeated loading cycles. However, my preliminary fundamental experiments using a microasperity reveal that cracks can develop even during the first friction stroke. Moreover, I observed that the crack evolution is grain orientation dependent: while cracks develop in one grain, another grain is crack free although both grains experience the same loading. This project investigates the basic mechanisms of crack growth and the interaction of micro-cracks and micro-plasticity in unlubricated contacts of an engineering FCC steel and a corresponding BCC model-alloy. Using micrometer experiments with auxiliary simulations, I will determine grain orientation dependent crack formation, the crack growth rate and subsequent loading. With the fundamental understanding of crack initiation due to a single microasperity, one can acquire a better understanding of macroscale tribology, which is the combined contact and interaction of a multitude of microasperities. This improved macroscale understanding can result in a reduction of wear and friction and, hence, in a reduction of replacement costs, noise and energy consumption.

• DFG Programme: Research Grants