Steel, the backbone of modern manufacturing, owes its origins to a serendipitous discovery. Early blacksmiths found that heating iron with charcoal produced a much stronger alloy. Nowadays, high-strength steels can also be produced by adding other alloying elements, such as nickel. Steel remains indispensable, valued for its strength and versatility in everything from aerospace components to industrial tools.
A particularly robust variety, maraging steel, is renowned for its high strength and ductility. Its standout feature is its compatibility with additive manufacturing, making it ideal for printing intricate metal parts.
Jakub Mikula, a Senior Scientist at the A*STAR Institute of High Performance Computing (A*STAR IHPC), attributed maraging steel’s unique properties to its microstructure—a finely tuned arrangement known as lath martensite. “This hierarchical structure spans multiple scales and can be tailored by adjusting manufacturing parameters,” Mikula explained.
Understanding how these intricate patterns and layers influence strength and durability has long been a challenge. Traditional experiments often fail to isolate the effects of the steel’s complex internal features. “To analyse the microstructure-property relationship, it’s necessary to isolate and establish correlations at different length scales first and then tie them together,” said Mikula.
Together with industry partners Entegris and Proterial, an A*STAR IHPC team led by Yong-Wei Zhang, Guglielmo Vastola and Mikula tackled this problem by creating an advanced virtual model of maraging steel using computer simulations. Their work relied on crystal plasticity models and finite element simulations, which are computational tools designed to mimic how the steel deforms under stress.
“These models are perfect for capturing the hierarchical nature of laths, blocks and packets within martensite,” said Vastola. This detailed approach allowed the researchers to unravel the relationship between microstructure and maraging steel’s mechanical properties.
The team generated synthetic microstructures to replicate realistic features such as melt pool boundaries and martensitic blocks. Their simulations revealed that smaller grains and densely packed dislocations significantly enhanced strength, while the unique behaviour of non-planar dislocation cores may be responsible for steel responding differently to stretching and compression.
"Unlike experiments, our simulations allow us to isolate specific microstructural effects and uncover correlations that are often too complex to disentangle from experimental data alone,” said Mikula.
This can help manufacturers fine-tune production efficiently, boosting strength while keeping their costs in check. By embedding their tool into a digital framework, the team envisions a future where the entire manufacturing process can be simulated on a computer. This leap could sideline expensive trial-and-error approaches, paving the way for faster, more reliable materials development.
The A*STAR-affiliated researchers contributing to this research are from the A*STAR Institute of High Performance Computing (A*STAR IHPC).
