Tensile Test: 1045 Normalized Construction-Grade Steel

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ABSTRACT
A tensile test is performed on a sample of 1045 normalized construction-grade steel using an Intron load frame. A graph of the engineering stress versus strain of the 1045 steel specimen is constructed from the data collected in the tensile test. Mechanical properties such as the ultimate strength, the fracture strength, and the Young’s modulus of the sample are obtained by further analyzing the stress versus strain graph. These experimental values are compared to the expected mechanical properties of the tested material provided by a reference. The percent difference between the expected and experimental values of the ultimate strength is 13.5% and that of the modulus of elasticity is 9.42 %. INTRODUCTION Background
In many engineering …show more content…

The diameter of the grip section is then measured and recorded after the gage diameter is acquired. The specimen is then loaded onto the testing machine and the upper grip of the load frame is tightened by turning the handle above the upper grip. The jog button is used to lower the crosshead to center the specimen between the two grips[2]. Once the specimen is aligned, the lower grip is tightened up by turning the lower handle. The crosshead position is then initialized by using the control panel and the extension display is set to be zero. Next, an extensometer is attached firmly to the gage section of the specimen to measure the change in length. The strain indicator in the computer program is ascertained to be close to zero. After calibrating and double-checking the set-up, the tension test begins and the computer program starts to collect the data when the “Start” button is …show more content…

Compared to the expected value, the ultimate strength obtained from the experiment, 647 MPa, is greater than the anticipated value. The percent difference between the expected and experimental values is 13.5%. There is also a discrepancy between the expected and experimental values of modulus of elasticity of 1045 steel. The expected value of modulus of elasticity is 200 GPa[3] while the experimental value is 182 GPa, which is slightly smaller than expected. The percent difference calculated is 9.42 %.
One of the possible sources of error is the sample size. The expected mechanical properties are obtained based on multiple repetitive experiments on 1045 steel specimens of different dimensions, whereas only one sample is tested in this experiment. By increasing the sample size, the experimental values might be closer to the theoretical mechanical properties. In addition, failure to calibrate or check zero of the equipment used could affect the accuracy of the instrument, and therefore could result in the discrepancies between the expected and experimental values.

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