Fomal Lab On Hardnessimpacttensile Tests

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Mechanical Testing: Hardness, Impact, and Tensile Testing
ME 3701-02
March 8, 2013
Robert Levy
Abstract
The goal of this experiment was to test the hardness, impact resistance, and tensile
strength of different metallic samples. The three tests used were the Charpy impact test,
Rockwell Hardness test, and tensile strength test. As defined by the lab manual, “Rockwell
Hardness Testing consists of measuring the additional depth to which an indenter is forced by a
major load beyond the depth of a previously applied minor load…”[1]. Through the testing of the
steel, aluminum, and brass samples we found that steel was the hardest with an average hardness
rating of 22.965HRC followed by aluminum with a rating of 66.58HRB and lastly brass with a
rating of 44.96HRB. The Charpy test was performed on two steel samples at different
temperatures. The steel sample at room temperature (25C) absorbed 26 joules of energy while
the sample at -79C absorbed only 4 joules of energy showing that steel is weaker at extremely
low temperatures. Tensile testing was performed on one aluminum and one steel sample.
Chauvenet’s criteria was applied to eliminate faulty data from the plots, but the data remains in
the tables themselves. Through the tensile testing, we determined that the aluminum was more
ductile than the steel as expected.
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TABLE OF CONTENTS
Title page 1
Abstract 1
TOC 2
Nomenclature 3
Figures and tables 4
Introduction 5
Experimental Apparatus and Procedures 7
Results 8
Discussion 11
Conclusion 12
References 13
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LIST OF NOMENCLATURE
Hardness- a measure of a material’s resistance to localized plastic deformation.
Toughness-a measure of the amount of energy a material can absorb before fracturing.
Minor Load-initial load applied to a specimen in the Rockwell test to eliminate backlash in the
load train and cause the indenter to break through slight surface roughness to improve accuracy.
Major Load-secondary load applied a specimen that is applied at a prescribed, controlled rate.
Impact test-a method to discover a specimen’s toughness.
Chavenet’s Criterion-A method to process the data following Gaussian distribution.
Tensile-the ability of a metal to be stretched out and the limit thereof.
Tensile Test-a test to determine the reaction of a material to an applied force.
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Document Summary

The goal of this experiment was to test the hardness, impact resistance, and tensile strength of different metallic samples. The three tests used were the charpy impact test, Hardness testing consists of measuring the additional depth to which an indenter is forced by a major load beyond the depth of a previously applied minor load [1]. The charpy test was performed on two steel samples at different temperatures. The steel sample at room temperature (25c) absorbed 26 joules of energy while the sample at -79c absorbed only 4 joules of energy showing that steel is weaker at extremely low temperatures. Tensile testing was performed on one aluminum and one steel sample. Chauvenet"s criteria was applied to eliminate faulty data from the plots, but the data remains in the tables themselves. Through the tensile testing, we determined that the aluminum was more ductile than the steel as expected. Hardness- a measure of a material"s resistance to localized plastic deformation.

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