Coatings, Vol. 15, Pages 1270: Mechanistic Study of Surface Nanocrystallization for Surface Modification in High-Strength Low-Alloy Steel

Coatings doi: 10.3390/coatings15111270

Authors:
Yiyang Jin
Feng Ge
Pengfei Wei
Yixuan Li
Lingli Zuo
Yunbo Chen

This study systematically investigates the surface nanocrystallization of 35CrMo steel induced by Ultrasonic Surface Rolling Processing (USRP). It reveals the formation of a gradient nanostructure, where martensite lath fragmentation under high-frequency impacts leads to a surface layer of equiaxed nanocrystals and high-density dislocations. This novel microstructure yields exceptional surface integrity: roughness is minimized to 0.029 μm due to plastic flow, residual stress is transformed into high compressive stress, and surface microhardness is significantly enhanced by 32.3%, primarily governed by grain refinement and dislocation strengthening. Consequently, the treated material exhibits a 28.9% reduction in wear mass loss, which is directly attributed to the combined effects of the strengthened gradient layer’s improved load-bearing capacity and the effective suppression of crack initiation by compressive residual stresses. Our findings not only provide direct microstructural evidence for classic strengthening theories but also offer a practical guide for optimizing the surface performance of high-strength alloy components.

Source link

Yiyang Jin www.mdpi.com