An Investigation of Effect of Tin (Sn) on Microstructures and Mechanical Properties of Gray Cast Iron

Selcuk University, Turkey

doi:10.26666/rmp.jesr.2019.5.4

Abstract

As the tensile strength of gray cast iron is low, it is tried to increase tensile strength by testing various alloying elements. The most preferred of these alloying elements was the copper element. However, it is known that copper increases both hardness and tensile strength by enhancing perlite ratio in microstructure. On the other hand, when tin (Sn) is used in trace amounts compared to copper, it has similar effects on hardness and tensile strength of cast iron. In this study, adding tin element of 0,03-0,06-0,09-0,12-0,15 % by weight in gray cast iron, its effect on tensile strength was investigated and the appearance of the fracture surfaces was examined. It was compared with two different gray cast irons containing 0.4% copper element and free of alloying elements. According to the tensile strength results, the highest tensile strength was observed to be 195 N / mm2 in the specimen number 6 containing 0,12% Sn. The lowest tensile strength was determined as 157 N / mm2 in the specimen number 1 which did not contain alloying elements. In SEM (Scanning Electron Microscopy) images, it is seen that the samples generally exhibit a brittle rupture behaviour. In some of the specimens with the addition of tin and copper, regional ductile rupture behaviours were observed.

Highlights

In 1948, the first indication that tin in cast iron could cause significant changes in the microstructure was found by the Canadian Mining Office in Ottawa [1]
In a study in 2007, Novytsky et al reported that the tensile strength and hardness of cast iron increased in direct proportion to the perlite ratio of the matrix in the microstructure and the amount of perlite in the morphology increased with increasing amount of tin [7]
In another study conducted in 1969, Thwaites emphasized that the tensile strength increased in parallel with the increase in the perlite amount in the microstructure and perlite ratio in gray cast iron could increase with the addition of tin element

Summary

INTRODUCTION

In 1948, the first indication that tin in cast iron could cause significant changes in the microstructure was found by the Canadian Mining Office in Ottawa [1]. It was determined that perlite matrix in cast iron increased between 0,025-0,09 % Sn with increasing tin ratio. There is a variety of literature about the effect of tin in cast iron with lamellar graphite on tensile strength. Veresh concluded that the tensile strength of gray cast iron decreased consistently as the tin content increased [5]. Dawson et al showed in their study in 2001 that the addition of tin to cast iron increased Brinell hardness value and tensile strength concordantly [6]. In a study in 2007, Novytsky et al reported that the tensile strength and hardness of cast iron increased in direct proportion to the perlite ratio of the matrix in the microstructure and the amount of perlite in the morphology increased with increasing amount of tin [7].

SEM Analysis The thermal fatigue test was done in a thermal cyclic furnace

Tensile Test Results

SEM Analysis Results