研究目的

Investigating the microcracking in Selective Laser Melting (SLM) of tungsten to understand the influence of process parameters on crack formation and to provide experimental evidence that the ductile-to-brittle transition is the main cause of the microcracks.

研究成果

Using in-situ high speed monitoring, the exact moment of crack initiation during Selective Laser Melting of W was characterized. It was found that a high laser power reduces the number of cracks through a higher crack spacing, and that the time it takes for a crack to form after passage of the melt pool correlates with the linear energy input P/v. The in-situ observation of delayed cracking provides experimental evidence that the ductile-to-brittle transition is the major metallurgical phenomenon contributing to microcracking in W.

研究不足

The stochastic nature of microcracking and local variations in grain boundary area, misorientation, and possible defects may lead to earlier or delayed formation of a crack or even inhibit a crack to form in a specific location. The large spread of the results reflects these variations.