Effect of Active Screen Plasma Nitriding on Mechanical Properties of Spheroidal Graphite Cast Iron

Yasuhiro Hoshiyama,Keisuke Chiba,Tomoki Maruoka

doi:10.3390/met11030412

Abstract

Spheroidal graphite cast iron is a material with a wide range of uses such as in automobile parts. By applying active screen plasma nitriding (ASPN) treatment, the use of spheroidal graphite cast iron is expanded, and it can be expected to be used under special load conditions. In this study, we evaluated the effect of ASPN treatment on the mechanical properties of spheroidal graphite cast iron. With ASPN treatment, a nitride layer was formed on the sample surface and a diffusion layer was formed further inside the nitride layer. The thickness of nitride layer increased as the treatment temperature increased. The hardness was improved by ASPN treatment. The abrasion resistance was improved by ASPN treatment, and longer treatment time resulted in higher abrasion resistance. The fatigue strength was improved by ASPN treatment, and longer treatment time resulted in higher fatigue strength. ASPN treatment also improved the corrosion resistance.

Highlights

Cast iron is used as a raw material for various products, such as industrial and mechanical parts
Depending on the application, treatments aimed at appropriate surface modification are performed to improve the wear resistance and fatigue strength of cast iron [1,2,3,4]
One of the methods used for surface modification is plasma nitriding

Summary

Introduction

Cast iron is used as a raw material for various products, such as industrial and mechanical parts. Depending on the application, treatments aimed at appropriate surface modification are performed to improve the wear resistance and fatigue strength of cast iron [1,2,3,4]. An external heating device is unnecessary since the material to be treated is heated by the collision energy of ions. The treatment time is short as it utilizes nitrogen in the active plasma state. The process is economical as there is less consumption of energy and gas, and there is no burden on the environment because toxic substances are not employed by utilizing abundant resources of nitrogen and hydrogen. The surface temperature of the material to be treated is increased, and its surface is cleaned by the sputtering action of a mixed gas of nitrogen and hydrogen.

Methods

Discussion

Conclusion