# Surface Characteristics and Fatigue Resistance of Ultrasonic Rolling-Treated 20Cr1Mo1V1A Valve Stem

## TL;DR

Ultrasonic rolling improves the surface and fatigue resistance of a specific valve stem material, making it more durable and corrosion-resistant.

## Contribution

A novel application of ultrasonic rolling to enhance mechanical and corrosion properties of 20CrMo1V1A valve stems.

## Key findings

- USR reduced surface roughness to 0.3 μm and created a gradient nanostructure.
- Surface hardness improved by 27% and grain size decreased nearly three-fold.
- Friction coefficient and corrosion rate dropped by 47% and 32%, respectively.

## Abstract

The valve stem made of 20CrMo1V1A has low surface resistance and high susceptibility to corrosion, significantly curtailing its service life. To address these issues, a high-quality ultrasonic rolling (USR) technology was applied to the 20CrMo1V1A stainless steel valve stem to enhance its corrosion resistance and mechanical properties. Subsequently, fatigue and corrosion tests were conducted on the valve stem. The results indicate that USR produces surfaces with a roughness average (Ra) of 0.3 μm and a gradient nanostructure on the valve stem surface. This unique microstructural modification resulted in a 27% improvement in surface hardness and nearly a three-fold grain size reduction. Additionally, the friction coefficient and electrochemical corrosion rate dropped by 47% and 32%, respectively. Therefore, USR was applicable for enhancing multiple properties of valve components as an additional final processing step for achieving high-performance valve stems.