Whenever people try to improve materials like steel, they may eventually introduce new weaknesses at the same time. This is a frustrating fact, and this is a balancing act between different properties. Engineers have now developed a new type of "super steel" that can resist this trade-off, while maintaining strength while resisting fracture.
For materials like steel, there are three main attributes that need to be balanced–strength, toughness, and ductility. The first two may sound the same, but there is an important difference. Strength refers to how much load the material can withstand before deformation or failure, while toughness refers to the amount of force required to break the material. For reference, glass has relatively high strength, but low toughness, so it can withstand considerable weight, but does not require much force to break.
Finally, ductility is a measure of whether a material can easily stretch or stretch into different shapes. Unfortunately, improving one of these three performances tends to reduce the other performance. For example, increasing the strength often reduces the toughness or ductility of the material.
But now, researchers from the University of Hong Kong and the Lawrence Berkeley National Laboratory in the United States say they have successfully produced a steel with advanced properties in all three properties. They boldly called it "super steel". The deformation resistance of this new material is about 2GPa, the fracture toughness is 102MPa-m, and the uniform elongation is 19%. The team said that this makes this "super-strength steel" stronger and tougher than Grade 300 maraging steel used in aerospace engineering-and the manufacturing cost of this new steel is only about 20% of its price.
This super steel is manufactured using a new deformation distribution method (D & P), and its toughness comes from a unique design feature. When the surface of the material breaks, a number of tiny cracks will form below it. These small cracks will continue to absorb the energy of external forces, preventing the main crack from spreading too quickly.
The team said the new super steel may find use in high-strength bridge cables, body armor, and automotive springs. "We have taken a big step towards the industrialization of new super steels," said Huang Mingxin, the study's lead author. "It shows great application potential and can be applied in various fields, including super-strong body armor, bridge cables, light automobiles and military vehicles, high-strength bolts and nuts in the aerospace and construction industries.