Chemistry Material Science Lab Consulting Report

Topics: Tensile strength, Yield, Elasticity Pages: 5 (498 words) Published: May 31, 2015
Consulting Report

Mechanical Properties
Cold-Rolled Steel

Student: Predrag Bogunovic
STUDENT ID: 11807777
DATE: 4-APR-2014

1 TABLE OF CONTENTS
1

Introduction .................................................................................................................................... 2

2

Methods .......................................................................................................................................... 2

3

Results............................................................................................................................................. 3

4

Discussion........................................................................................................................................ 4

5

Conclusion ....................................................................................................................................... 4

1

1 INTRODUCTION
This report elaborates on mechanical properties such as 0.2% Offset Proof Stress, Ultimate Tensile Stress and Young’s Modulus of cold-rolled steel. This material will be used by Ace Flying Fox Ltd for the purpose of building a prototype supporting gantry which has to sustain a maximum stress of 670MPa.

2 METHODS
Five samples of cold-rolled steel of 50mm gauge length, 3mm thickness and 12.5mm width are tested to AS 1931-2007 Metallic Materials – Tensile Testing at Ambient Temperature with SHIMADZU Tensile Strength Tester Machine.

Fig 1. SHIMADZU Tensile Strength Tester Machine.

The data is collected in the sense of Applied Load (N) vs. Displacement (mm). Average Applied Load and Displacement from all five specimens is then used to calculate the Stress (MPa) and Strain. Stress/Strain graph is then plotted in order to find the Yield Point (YP) and Ultimate Tensile Stress (UTS) by visual inspection of the graph. Young’s Modulus is then found by dividing Stress by Strain in the elastic region. 0,002 Strain is located on the Strain axis of the graph and a line parallel to the loading line in the elastic region is drawn up to the point where it intersects the graphed curve. The point of intersection is then projected onto the Stress axis and 0.2% Offset Proof Stress is found.

2

3 RESULTS
0.2% Proof Stress

Yield Point (approx.)

0.002 Strain

Fig 2. Stress/Strain Graph of the processed results.

The Stress/Strain graph shows that the asked for mechanical properties of coldrolled steel are as listed bellow: Ultimate Tensile Strength (UTS)
0.2% Offset Proof Stress
Young’s Modulus (E)

754.66 MPa
615 MPa (approx.)
200 GPa

3

4 DISCUSSION
In general, the results for mechanical properties obtained from the Stress/Strain graph appear to be within the range of typical values for mechanical properties of cold-rolled steel found elsewhere. The steep slope of elastic region shows that the material is very stiff and a long plastic region shows that the material is quite ductile. The Yield Point is approximated at about 600MPa. 0,2% Proof Stress is about 615MPa and this is the maximum stress that this particular material can withstand before it plastically deforms.

This cold-rolled steel is not suitable for the prototype gantry design project as its transition from elastic to plastic deformation occurs under lower applied pressure (615MPa) than the maximum service pressure proposed (670MPa).

5 CONCLUSION
Having performed tensile testing of the cold-rolled steel specimens and acquiring mechanical properties data, it can be concluded that either material with 0,2% Proof Stress higher than 670MPa needs to be selected or the current design needs to be amended to reduce the value of maximum service pressure to under 615MPa in order to use cold-rolled steel.

4

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