Researchers from the Institute of Metal Research, Chinese Academy of Sciences (IMR, CAS) have developed a new type of nanocrystalline 304 stainless steel that simultaneously overcomes the traditional trade-off between strength and corrosion resistance in metallic materials.

Published in Sustainable Materials and Technologies,the study details how a team led by Prof. WANG Shenggang used an advanced severe rolling technique to produce bulk nanocrystalline 304 stainless steel sheets (NC-304) with a precisely controlled microstructure. This breakthrough solves a critical  barrier to using nanostructured metalsin industry-their typically heightened vulnerability to corrosion under mechanical stress.

The NC-304 steel demonstrates exceptional performance across multiple criteria. It shows significantly improved mechanical properties with yield strength increases of 303-429 MPa while maintaining good ductility (36.5%-52.1% elongation). More importantly, it also exhibits superior corrosion resistance with a 400 mV higher pitting potential and 370 mV wider passive region compared to conventional 304 stainless steel.

A key achievement is the material's consistent performance under varying strain rates an in harsh conditions, such as prolonged exposure to concentrated hydrochloric acid.

The simultaneous improvement in strength and corrosion resistance defies conventional understanding. And by manipulating the valence electron structure through nanocrystallization,we have provided a new pathway for designing high-performance structural materials.

The successful development of NC-304 stainless steel sheets promises significant implications for various industries from chemical processing to transportation, paving the way for lighter, more durable, and energy-efficient components.

Strain fatigue, electrochemical corrosion, stress corrosion, and high-temperature oxidation performance of nanocrystalline and conventional 304 stainless steel. (Image by IMR)

Effect of strain rate on tensile (nanocrystalline and conventional 304 stainless steel) and corrosion (after tensile fracture of nanocrystalline and conventional 304 stainless steel) performance. (Image by IMR)