A joint research team from the University of Birmingham (Birmingham, United Kingdom), Stockholm University (Stockholm, Sweden), and Zhejiang University (Hangzhou, Zhejiang, China) optimized process parameters during three-dimensional (3-D) printing of stainless steel to achieve exceptional levels of both strength and ductility when compared to counterparts from more conventional processes. The discovery is crucial to moving the technology forward for manufacturing heavy-duty parts.
The 3-D printing technique is known to produce objects with previously inaccessible shapes; however, the quality of the products from metal 3-D printing has been prone to skepticism. In most metal 3-D printing processes, products are directly built up from metal powders, which makes them susceptible to defects, thus causing deterioration of mechanical properties.
The researchers’ work shows the possibility of producing the next generation of structural alloys with significant improvements in both strength and ductility. This is made possible by the ultrafast cooling rate, estimated to range from 1,000 to 100 million °C per second—something that was not possible in the bulk metal production process until the emergence of 3-D printing.
According to the researchers, the result of metals being cooled down so quickly is a non-equilibrium state that allows some amazing microstructures, such as the sub-microsize dislocation network, which was revealed to be the main reason of the improved mechanical properties.
This work provides researchers a new tool for designing new alloy systems with ultra-mechanical properties. It also helps metal 3-D printing to gain access into fields where high mechanical properties are required, such as structural parts in aerospace and automotive industry.
Source: University of Birmingham, www.birmingham.ac.uk.