Scratch Behaviour of Silicon Solid Solution Strengthened Ferritic Compacted Graphite Iron (CGI)

Rohollah Ghasemi,Anders E.W Jarfors

doi:10.4028/www.scientific.net/msf.925.318

Abstract

The present study focuses on scratch behaviour of a conventional pearlitic and a number of solid solution strengthened ferritic Compacted Graphite Iron (CGI) alloys. This was done by employing a single-pass microscratch test using a sphero-conical diamond indenter under different constant normal loads conditions. Matrix solution hardening was made by alloying with different content of Si alloy; (3.66, 4.09 and 4.59 wt%. Si) which are named as low-Si, medium-Si and high-Si ferritic CGI alloys, respectively. A good correlation between the tensile and scratch test results was observed explaining the influence of CGI’s matrix characteristics on scratch behaviour both for pearlitic and fully ferritic solution strengthened ones. Both the scratch depth and scratch width showed strong tendency to increase with increasing the normal load, however the pearlitic one showed more profound deformation compared to the solution strengthened CGI alloys. Among the investigated alloys, the maximum and minimum scratch resistance was observed for high-Si ferritic CGI and pearlitic alloys, respectively. It was confirmed by the scratched surfaces analysed using Scanning Electron Microscopy (SEM) as well. In addition, the indenter’s depth of penetration value (scratch depth) was found as a suitable measure to ascertain the scratch resistance of CGI alloys.Keywords: Silicon solution strengthening, CGI, Abrasion, Scratch testing, Scratch resistance

Highlights

Pearlitic Compacted Graphite Iron (CGI) is characterised by its unique graphite morphology within the metal matrix which provides an intermediate mechanical and physical properties between the lamellar and spheroidal graphite cast irons
CGI alloys are commonly selected as suitable candidates for high mechanical and pressure applications such as diesel engine components [1]
This study presents an experimental simulation of a rigid sphero-conical indenter sliding against a pearlitic and a number of fully ferritic CGI alloys which have been solution strengthened by different Si contents

Summary

Introduction

Pearlitic Compacted Graphite Iron (CGI) is characterised by its unique graphite morphology within the metal matrix which provides an intermediate mechanical and physical properties between the lamellar and spheroidal graphite cast irons. CGI alloys are commonly selected as suitable candidates for high mechanical and pressure applications such as diesel engine components [1]. In recent years, CGI alloys with fully ferritic matrix have received a great attention for promising satisfactory mechanical and physical properties for the generation of cast irons [2, 5]. Fully ferritic CGI alloys have been recently received more attention in industrial applications where good machinability does importantly matter, while maintaining the strength

Methods

Results

Conclusion