Abstract

There have been very few reports describing the free machining lead free aluminum alloys containing minimal amounts of tin and indium melt spun process. Our paper describes the effect of fundamental factors on the machinability of free machining lead free aluminum alloys rapidly solidified from melt. Structural and thermal properties have been investigated by x-ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques. Tensile test machine used in studies the mechanical properties such as ultimate tensile strength, elastic constants, yield strength and critical shear stress for Al-Zn-Sn-In alloys. It is noticed that mechanical and thermal properties attributed to fine grained structure, reduced levels of segregation and presence of new intermetallic compounds (IMC) such as AlZn and SnZn due to high casting rate by rapid solidification processes. The determination of mechanical properties was suggested to be attributed to the gradual increase of α-Al crystals. We evaluated the tensile properties using tensile test machine of the melt-spun ribbons at varied stress-strain rates to determine the underlying deformation mechanisms .Critical shear stress (CSS) was also calculated .It was found that it is equal to 9.29 GPa for annealed ribbons at 262 0C for 9 hrs. The results showed that several combination of tensile strength ,yield strength ,elastic moduli can be generated from Al- 0.1wt% Zn-1.5 wt% Sn- 1.63 wt% In alloys before and after heat treatment at (262 0C for 3,6,9 hrs) to meet the needs of free machining aluminum alloy applications.

Highlights

  • It is well known that metallic liquids are extremely unstable and crystallize almost immediately at temperatures lower than melting point

  • The finer and more homogeneous microstructure leads to suitable effect on the mechanical properties of free machining aluminum alloys

  • The hardness increases when the alloy is heated at 262 OC

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Summary

INTRODUCTION

It is well known that metallic liquids are extremely unstable and crystallize almost immediately at temperatures lower than melting point. Free machining aluminum alloys used for machining operations such as drilling, milling, turning, etc This means that if the factors against the cutting tools are low the melt-spun ribbons used in this work are machinable. These alloys typically include free machining constituents such as lead, tin, indium and bismuth for improved machinability. Through the increased volume and by the edge effect generated tension ,the ductility of the material in the working zone causes the easy breaking of the chips[5,8,9].During machining, free-machining alloys generate small chips or curls which are collected and do not interfere with the machining process. The current research paper focuses on chip breaking inclusions in machining aluminum alloys where lead is substituted by tin and indium

MATERIALS AND SAMPLE PREPARATION
SAMPLE CHARACTERIZATION
Tensile Test Machine
Microhardness
Structure
Microstructure Analysis
Melting Behavior
Elastic Moduli And Tensile Properties
CONCLUSIONS
Full Text
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